Electronics and Accessories

Abstract

To enable an accessory to send a notification to an electronic device. An accessory 200 is detachably attached to an electronic device 100. An accessory processing means 201 notifies the electronic device 100 by validating a communication request signal connected to a communication request contact TA11.

Description

[Technical Field]

[0001] The present invention relates to an electronic device such as an imaging device to which accessories can be attached. [Background technology]

[0002] In a system consisting of an electronic device and a detachable accessory, various commands, notifications, and information are communicated via multiple contacts. Patent Document 1 discloses that an imaging device as an electronic device detects that an accessory is attached and then notifies the accessory of communication permission using an interrupt signal, and then the imaging device acquires accessory information from the accessory through communication. In Patent Document 1, the imaging device determines whether to supply power to the accessory based on the acquired accessory information (information for identifying the accessory). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-238875 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the system disclosed in Patent Document 1, the electronic device (imaging device) notifies the accessory of permission to communicate accessory information. On the other hand, various improvements are required for notifications from the accessory to the electronic device.

[0005] The present invention provides an electronic device and an accessory that allow the accessory to send a notification to the electronic device. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an accessory detachably attached to an electronic device. The accessory has a communication request contact, a communication contact, and an accessory processing means for communicating with the electronic device using the communication request contact and the communication contact. When the accessory is attached to the electronic device and communication with the electronic device is possible, the accessory processing means first enables a communication request signal connected to the communication request contact, thereby permitting a request from the electronic device for accessory information for identifying the accessory, and in response to the request, transmits the accessory information to the electronic device via the communication contact. After transmitting the accessory information, the communication request signal is re-enabled to notify the electronic device of the communication request, and the cause of the communication request is transmitted via the communication contact to the electronic device that responded to the communication request. It is characterized by:

[0007] Another aspect of the present invention is an electronic device to which an accessory is detachably attached. The electronic device has a communication request contact, a communication contact, and processing means for communicating with the accessory using the communication request contact and the communication contact. When the accessory is attached to the electronic device and communication with the accessory is possible, the processing means requests the accessory to transmit accessory information for identifying the accessory when a communication request signal connected to the communication request contact is first enabled by the accessory, and receives the accessory information transmitted from the accessory in response to the request via the communication contact. After receiving the accessory information, the communication request signal is re-enabled by the accessory to receive a communication request notification, and in response to the communication request, a communication request cause is received from the accessory via the communication contact. A system including the accessory and electronic device also constitutes another aspect of the present invention.

[0008] Another aspect of the present invention is a control method applied to an accessory that is detachably attached to an electronic device and has a communication request contact and a communication contact, the control method including the steps of: when the accessory is attached to the electronic device and communication with the electronic device is possible, enabling a communication request signal connected to the communication request contact for the first time to allow a request from the electronic device for accessory information for identifying the accessory; and, in response to the request, transmitting the accessory information to the electronic device via the communication contact. a step of notifying the electronic device of a communication request by re-enabling the communication request signal after transmitting the accessory information; and a step of transmitting a communication request cause via the communication contact to the electronic device that responds to the communication request. The present invention is characterized by having the following.

[0009] A control method according to another aspect of the present invention is applied to an electronic device to which an accessory is detachably attached and which has a communication request contact and a communication contact, the control method including the steps of: requesting the accessory to transmit accessory information for identifying the accessory when a communication request signal connected to the communication request contact is first enabled by the accessory when the accessory is attached to the electronic device and communication with the accessory is possible; and receiving the accessory information transmitted from the accessory in response to the request via the communication contact. receiving notification of a communication request by the accessory re-enabling the communication request signal after receiving the accessory information; and receiving a communication request cause from the accessory via the communication contact in response to the communication request. The present invention also provides a program for causing a computer of the accessory or electronic device to execute processing according to the control method. [Effects of the Invention]

[0010] According to the present invention, a notification can be sent from an accessory to an electronic device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of a camera system (camera, lens unit, and accessories) in a first embodiment. [Figure 2] FIG. 3 is a diagram showing a protocol of SPI communication in the first embodiment. [Figure 3] 4 is a flowchart showing processing performed by the camera and the accessory in the first embodiment. [Figure 4] FIG. 4 is a diagram showing communication data in SPI communication in the first embodiment. [Figure 5] FIG. 4 is a diagram showing accessory information in the first embodiment. [Figure 6] FIG. 3 is a diagram showing a processing sequence of the camera system according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing accessory type information according to the first embodiment. [Figure 8] FIG. 3 is a diagram showing factors that cause a communication request in the first embodiment. [Figure 9] FIG. 4 is a diagram showing a communication interval in SPI communication according to the first embodiment. [Figure 10]5 is a flowchart showing a startup process performed by the camera (camera control circuit A) in the first embodiment. [Figure 11] 6 is a flowchart showing a startup process performed by the camera (camera control circuit B) in the first embodiment. [Figure 12] 4 is a flowchart showing a process performed by an accessory in the first embodiment. [Figure 13] FIG. 1 is a diagram showing the configuration of a camera and accessories according to a first embodiment. [Figure 14] 4 is a flowchart showing processing performed by the camera and the accessory in the first embodiment. [Figure 15] FIG. 10 is a diagram showing the configuration of a camera, an accessory, and a second accessory in a second embodiment. [Figure 16] 10 is a flowchart showing processing performed by a camera, an accessory, and a second accessory in the second embodiment. [Figure 17] FIG. 11 is a diagram showing the configuration of a camera, an accessory, and a third accessory in the third embodiment. [Figure 18] 11 is a flowchart showing processing performed by a camera, an accessory, and a third accessory in the third embodiment. [Figure 19] FIG. 10 is a diagram showing an example of an I2C communication waveform. [Figure 20] 4 is a diagram showing a process performed by the camera when transmitting N bytes of data from the camera to the accessory in the first embodiment. FIG. [Figure 21] 4 is a diagram showing a process performed by the camera when the camera receives N bytes of data from the accessory in the first embodiment. FIG. [Figure 22] 10 is a diagram showing a process performed by the accessory when transmitting and receiving N bytes of data between the camera and the accessory in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Example]

[0013] 1 shows the electrical configuration of an imaging system including an imaging device (hereinafter referred to as camera) 100, which is an electronic device according to a first embodiment of the present invention, and an accessory 200 detachably attached to the imaging device. The accessory 200 is, for example, a microphone device or a lighting (strobe or flash) device, and includes various devices that can be attached to the camera 100. The camera 100 and the accessory 200 are electrically connected by one-to-one contact between a plurality of contacts (terminals) TC01 to TC21 of a camera connection section 141 provided on the camera 100 and a plurality of contacts TA01 to TA21 of an accessory connection section 211 provided on the accessory 200. Note that the accessory 200 may not have some of the plurality of contacts TA01 to TA21.

[0014] The camera 100 is supplied with power from a battery 111. The battery 111 is detachable from the camera 100. A camera control circuit A101 serving as a first processing means, control means, and receiving means in the camera 100, and a camera control circuit B102 serving as a second processing means, are circuits that control the entire camera 100, and are configured by a processor (microcomputer) such as a CPU. The camera control circuit A101 and the camera control circuit B102 perform various controls and processes according to computer programs.

[0015] The camera control circuit A101 monitors the operation of switches and other controls for operating the camera (not shown) and controls the system power supply in response to user operations. The camera control circuit A101 is configured with a low-power processor that can operate even when the camera 100 is in a power-saving state, which is a low-power consumption state. On the other hand, the camera control circuit B102 is responsible for controlling the image sensor 122, display circuit 127, etc. The camera control circuit B102 is configured with a processor that stops operating in the power-saving state and operates in the normal operating state.

[0016] In this embodiment, the camera control circuit A101 and the camera control circuit B102 are configured by separate processors, but they may be provided in a single processor.

[0017] The system power supply circuit 112 generates power supplied to each circuit of the camera 100 and is composed of a DC / DC converter circuit, an LDO (Low Drop Out), a charge pump circuit, etc. A voltage of 1.8V generated by the system power supply circuit 112, which receives power from the battery 111, is constantly supplied to the camera control circuit A101 as the camera microcomputer power supply VMCU_C. In addition, several types of voltages generated by the system power supply circuit 112 are also supplied to the camera control circuit B102 at any timing as the camera microcomputer power supply VMCU2_C. The camera control circuit A101 controls the system power supply circuit 112 to turn on and off the power supply to each circuit of the camera 100.

[0018] The optical lens 121 is detachably attached to the camera 100. Light from a subject incident through the optical lens 121 forms an image on an imaging sensor 122, which may be a CMOS sensor, a CCD sensor, or the like. The optical lens 121 and the camera 100 may be integrated. The subject image formed on the imaging sensor 122 is encoded into a digital imaging signal. The image processing circuit 123 performs image processing such as noise reduction and white balance processing on the digital imaging signal to generate image data, and converts the image data into an image file in JPEG format or the like for recording in the recording memory 126. The image processing circuit 123 also generates VRAM image data from the image data to be displayed on the display circuit 127.

[0019] The memory control circuit 124 controls the sending and receiving of image data generated by the image processing circuit 123 and other data. The volatile memory 125 is a memory capable of high-speed reading and writing, such as DDR3 SDRAM, and is used as a workspace for image processing performed by the image processing circuit 123. The recording memory 126 is a readable and writable recording medium, such as an SD card or CFexpress card, that can be attached to and detached from the camera 100 via a connector (not shown). The display circuit 127 is a display disposed on the rear surface of the camera 100, and is composed of an LCD panel, an organic EL display panel, or the like. The backlight circuit 128 adjusts the brightness of the display circuit 127 by changing the light intensity of the backlight of the display circuit 127.

[0020] The accessory power supply circuit A (first power supply means) 131 and the accessory power supply circuit B (second power supply means) 132 are each a voltage conversion circuit that converts the voltage supplied from the system power supply circuit 112 into a predetermined voltage, and in this embodiment generates 3.3 V as the accessory power supply VACC. However, a configuration for converting to another voltage is also possible. The accessory power supply circuit A131 is a power supply circuit with low self-consumption power, composed of an LDO and the like. The accessory power supply circuit B132 is a circuit composed of a DC / DC converter circuit and the like, and is capable of passing a larger current (i.e., supplying more power) than the accessory power supply circuit A131. The accessory power supply circuit B132 also consumes more self-consumption power than the accessory power supply circuit A131. For this reason, when the load current is small, the accessory power supply circuit A131 is more efficient than the accessory power supply circuit B132, and when the load current is large, the accessory power supply circuit B132 is more efficient than the accessory power supply circuit A131. The camera control circuit A101 controls the on / off of the voltage output of the accessory power supply circuit A131 and the accessory power supply circuit B132 depending on the operating state of the accessory 200.

[0021] The protection circuit 133 is configured with a current fuse element, a polyswitch element, or an electronic fuse circuit that combines a resistor, an amplifier, and a switch element. The protection circuit 133 outputs an overcurrent detection signal DET_OVC when the power supply current value supplied to the accessory 200 from the accessory power supply circuit A131 and the accessory power supply circuit B132 exceeds a predetermined value and becomes excessive (abnormal). In this embodiment, the protection circuit 133 is an electronic fuse circuit, and notifies the camera control circuit A101 with the overcurrent detection signal DET_OVC when a current of 1 A or more flows. The overcurrent detection signal DET_OVC indicates an overcurrent by going high. Note that the predetermined value may be configured to be different from 1 A.

[0022] The camera connection unit 141 is a connector for electrically connecting with the accessory 200 via 21 contacts TC01 to TC21 arranged in a row. The contacts TC01 to TC21 are arranged in this order from one end to the other in the arrangement direction.

[0023] TC01 is connected to ground (GND) and serves not only as a reference potential contact but also as a contact to control the wiring impedance of the differential signals D1N and D1P. TC01 corresponds to the third ground contact.

[0024] The differential signal D1N connected to TC02 and the differential signal D1P connected to TC03 are differential data communication signals that perform data communication in pairs and are connected to the camera control circuit B102. TC02, TC03, and TC07 to TC10, TC12 to TC17, TC19, and TC20, which will be described later, are communication contacts.

[0025] TC04 as a first ground contact is connected to GND and serves as a reference potential contact between the camera 100 and the accessory 200. TC04 is arranged further outward in the arrangement direction of the contacts than TC05, which will be described next.

[0026] An accessory power supply VACC generated by accessory power supply circuits A131 and B132 is connected to TC05 as a power supply contact via a protection circuit 133.

[0027] An accessory attachment detection signal / ACC_DET is connected to TC06 (fourth contact) as an attachment detection contact. The accessory attachment detection signal / ACC_DET is pulled up to the camera microcomputer power supply VMCU_C via a resistive element Rp134 (e.g., 10 kΩ). The camera control circuit A101 can detect whether the accessory 200 is attached by reading the signal level of the accessory attachment detection signal / ACC_DET. If the signal level (potential) of the accessory attachment detection signal / ACC_DET is a Hi level (predetermined potential), it is detected that the accessory 200 is not attached, and if it is a Lo level (GND potential) as an active potential, it is detected that the accessory 200 is attached.

[0028] When the power of the camera 100 is turned on, the signal level (electric potential) of the accessory attachment detection signal / ACC_DET changes from Hi level to Lo level, which triggers various communications between the camera 100 and the accessory 200 via the contacts.

[0029] In response to detecting that the accessory 200 is in an attached state, the camera control circuit 101 supplies power to the accessory 200 via TC05, which serves as a power contact.

[0030] The communication contacts SCLK connected to TC07, MOSI connected to TC08, MISO connected to TC09, and CS connected to TC10 are signals used by the camera control circuit B102 as the communication master to perform communication using the second communication method, SPI (Serial Peripheral Interface) communication method (hereinafter referred to as SPI communication). SCLK is the clock signal, MOSI is the transmission signal, MISO is the reception signal, and CS (chip select) is the communication selection signal that selects the communication partner. In this embodiment, the SPI communication has a communication clock frequency of 1 MHz, a data length of 8 bits (1 byte), a bit order of MSB first, and a full-duplex communication method.

[0031] In this embodiment, the camera 100 and the accessory 200 are compatible with two types of communication protocols as SPI communication methods. Communication protocol A is a communication method in which the camera 100 does not check whether the accessory 200 is in a communication-enabled state before outputting SCLK, and will be referred to as SPI protocol A in the following explanation. Figure 2(a) shows an outline of the communication waveform of SPI protocol A. In the figure, CS is set to Lo active.

[0032] The camera control circuit B102 changes CS to Lo level (active) at timing A1 to request the accessory control circuit 201 to perform SPI communication.

[0033] At timing A2, which is a predetermined time T_CS after timing A1, the camera control circuit B102 starts outputting SCLK and MOSI. Also, when the accessory control circuit 201 detects a falling edge of SCLK, it starts outputting MISO.

[0034] The camera control circuit B102 stops outputting SCLK at timing A3 when output of one byte of SCLK is completed.

[0035] Furthermore, the camera control circuit B102 stops outputting SCLK from timing A3 until a predetermined time T_INTERVAL has elapsed, and then resumes outputting SCLK at timing A4 when T_INTERVAL has elapsed, and communicates the next byte.

[0036] 3(a) shows the process performed by the camera control circuit B102 in the SPI protocol A. S means a step.

[0037] In S101, the camera control circuit B102 stores a numerical value indicating the number of bytes to be communicated in an internal variable N. For example, when communicating 3 bytes, 3 is stored.

[0038] In S102, the camera control circuit B102 changes CS to Lo level to request SPI communication.

[0039] In S103, the camera control circuit B102 changes CS to the Lo level and then performs a wait process until a predetermined time T_CS has elapsed, after which the process proceeds to S104.

[0040] In S104, the camera control circuit B102 controls the output of SCLK to communicate 1 byte of data, and also controls the output of MOSI data and the input of MISO data.

[0041] In S105, the camera control circuit B102 checks whether the internal variable N indicating the number of communication bytes is 0. If the internal variable N is 0, the process proceeds to S106, and if the internal variable N is other than 0, the process proceeds to S107.

[0042] In S107, the camera control circuit B102 subtracts 1 from the internal variable N indicating the number of communication bytes and stores the result as a new internal variable N.

[0043] In S108, the camera control circuit B102 performs wait processing until a predetermined time T_INTERVAL has elapsed since the communication of one byte of data was completed in S104. After the predetermined time T_INTERVAL has elapsed, the process returns to S104 and executes the same processing again.

[0044] In S106, the camera control circuit B102 changes CS to Hi level, and ends the series of SPI communications.

[0045] The flowchart in FIG. 3(b) shows the processing performed by the accessory control circuit 201 in the SPI protocol A.

[0046] In S201, the accessory control circuit 201 checks whether CS has changed to Lo. If CS has changed to Lo, the process proceeds to S202, and if CS has not changed to Lo, the process returns to S211.

[0047] In S202, the accessory control circuit 201 controls the input of MOSI data and the output of MISO data in response to the input of the SCLK signal, thereby communicating 1 byte of data.

[0048] In S203, the accessory control circuit 201 checks whether CS has changed to Hi. If CS has changed to Hi, it determines that the SPI communication has ended, and if CS has not changed to Hi, it returns to S202 to communicate the next byte.

[0049] Furthermore, communication protocol B in the SPI communication method is a communication method in which the camera 100 checks whether the accessory 200 is in a communication-enabled state before outputting SCLK, and will be referred to as SPI protocol B in the following explanation. Figure 2(b) shows an outline of the communication waveform of SPI protocol B.

[0050] The camera control circuit B102 changes CS to Lo level at timing B1 to request SPI communication from the accessory control circuit 201. The camera control circuit B102 also checks the potential of MISO along with the communication request. If MISO is Hi level, it determines that the accessory control circuit 201 is in a state where communication is possible, and if it is Lo level, it determines that the accessory control circuit 201 is in a state where communication is not possible.

[0051] On the other hand, when the accessory control circuit 201 detects the falling edge of CS at timing B2, it controls MISO to Hi level if SPI communication is possible, and controls MISO to Lo level if communication is not possible.

[0052] Furthermore, when the camera control circuit B102 confirms that MISO is at Hi level at timing B3, it starts outputting SCLK and MOSI. Furthermore, when the accessory control circuit 201 detects a falling edge of SCLK, it starts outputting MISO.

[0053] When the camera control circuit B102 completes output of one byte of SCLK at timing B4, it stops outputting SCLK.

[0054] After transmitting and receiving one byte of data, the accessory control circuit 201 controls MISO to Hi level if SPI communication is possible, and controls MISO to Lo level if SPI communication is not possible, as shown at timing B5 and timing B6.

[0055] The camera control circuit B102 checks the potential of MISO at timing B7. If MISO is at Hi level, it determines that the accessory control circuit 201 is in a state where communication is possible, and if it is at Lo level, it determines that the accessory control circuit 201 is in a state where communication is not possible.

[0056] The flowchart in FIG. 3(c) shows the processing performed by the camera control circuit B102 in the SPI protocol B.

[0057] In S111, the camera control circuit B102 stores a numerical value indicating the number of bytes to be communicated in the internal variable N. For example, when communicating 3 bytes, 3 is stored.

[0058] In S112, the camera control circuit B102 changes CS to Lo level to request SPI communication.

[0059] In S113, the camera control circuit B102 checks whether MISO has changed to Hi level. If MISO is at Hi level, the process proceeds to S114, and if MISO is not at Hi level, the process returns to S113.

[0060] In S114, the camera control circuit B102 performs output control of SCLK to communicate 1 byte of data, and also performs output control of MOSI data and input control of MISO data.

[0061] In S115, the camera control circuit B102 checks whether communication of all data has been completed (whether the internal variable N indicating the number of communication bytes is 0). If the internal variable N is 0, the process proceeds to S116, and if the internal variable N is other than 0, the process proceeds to S117.

[0062] In S117, the camera control circuit B102 subtracts 1 from the internal variable N indicating the number of communication bytes and stores the result as a new internal variable N.

[0063] In S118, the camera control circuit B102 checks whether MISO has changed to Hi level. If MISO is at Hi level, the process proceeds to S114, and if MISO is not at Hi level, the process returns to S118.

[0064] In S116, the camera control circuit B102 changes CS to Hi level, and ends the series of SPI communications.

[0065] The flowchart in FIG. 3(d) shows the processing performed by the accessory control circuit 201 in the SPI protocol B.

[0066] In S211, the accessory control circuit 201 checks whether CS has changed to Lo. If CS has changed to Lo, the process proceeds to S212, and if CS has not changed to Lo, the process returns to S211.

[0067] In S212, the accessory control circuit 201 checks whether or not SPI communication is possible. If SPI communication is possible, the process proceeds to S213, and if SPI communication is not possible, the process proceeds to S214.

[0068] In S213, the accessory control circuit 201 controls MISO to a Hi level and proceeds to S215.

[0069] In S214, the accessory control circuit 201 controls MISO to the Lo level and returns to S212.

[0070] In S215, the accessory control circuit 201 controls the input of MOSI data and the output of MISO data in response to the SCLK signal input, thereby communicating 1 byte of data.

[0071] In S216, the accessory control circuit 201 checks whether CS has changed to Hi. If CS has changed to Hi, it determines that the SPI communication has ended, and if CS has not changed to Hi, it returns to S212 to communicate the next byte.

[0072] FIG. 4 shows the contents of communication when an operation execution command is sent from the camera 100 to the accessory 200 by SPI communication in this embodiment.

[0073] In the first byte of communication, the camera control circuit B102 transmits, as MOSI data, information CMD indicating a command number to the accessory control circuit 201. The accessory control circuit 201 transmits, as MISO data, the value 0xA5, which is information indicating that communication is possible, to the camera control circuit B102. If the accessory control circuit 201 cannot execute the communication process for the first byte, it transmits, as MISO data, a value other than 0xA5 to the camera control circuit B102.

[0074] In the communication of the second byte, the camera control circuit B102 transmits the argument MOSI_DATA1 corresponding to the command number CMD to the accessory control circuit 201. Then, from the third byte to the (N-2)th byte onwards, the camera control circuit B102 similarly transmits the arguments MOSI_DATA2 to MOSI_DATA[N-3] corresponding to the command number CMD to the accessory control circuit 201.

[0075] In the second byte of communication, the accessory control circuit 201 transmits the command number CMD received in the first byte as MISO data to the camera control circuit B102. This allows the camera control circuit B102 to determine that the accessory control circuit 201 has correctly received the MOSI data.

[0076] Furthermore, in the communication of the third byte, the accessory control circuit 201 transmits the return value MISO_DATA1 corresponding to the command number CMD as MISO data to the camera control circuit B102. Then, from the fourth byte to the (N-2)th byte onwards, the accessory control circuit 201 similarly transmits arguments MISO_DATA2 to MISO_DATA[N-4] corresponding to the command number CMD to the camera control circuit B102.

[0077] The number of arguments and return values ​​is determined in advance for each command number. Either one or both of the arguments and return values ​​may be omitted.

[0078] In the (N-1)th byte of communication, the camera control circuit B102 transmits checksum data CheckSum_C as MOSI data to the accessory control circuit 201. The checksum data CheckSum_C is a value calculated by the following formula. CheckSum_C=EXOR(AND( SUM(CMD, MOSI_DATA1, …, MOSI_DATA[N-3]), 0xFF ), 0xFF ) In addition, the accessory control circuit 201 transmits 0x00 as the MISO data.

[0079] Next, the camera control circuit B102 transmits 0x00 to the accessory control circuit 201 as the MOSI data in the Nth byte of communication.

[0080] The accessory control circuit 201 also transmits checksum data CheckSum_A as MISO data. If the value of CheckSum_C received by the camera control circuit B102 in the (N-1)th byte of communication matches the value of CheckSum_C calculated by the camera control circuit B102, the checksum data CheckSum_A is calculated using the following formula. CheckSum_A=EXOR(AND(SUM(0xA5, CMD,MIS0_DATA1,…, MOSI_DATA[N-4]), 0xFF ), 0xFF ) On the other hand, if the value of CheckSum_C received by the camera control circuit B102 in the (N-1)th byte communication does not match the value of CheckSum_C calculated by the camera control circuit B102, the value is calculated using the following formula. CheckSum_A=AND(SUM(0xA5, CMD, MIS0_DATA1, …, MOSI_DATA[N-4] ), 0xFF ) A communication request signal (second input signal) / WAKE, which is used by the accessory 200 to request communication from the camera 100 (camera control circuit A101), is connected to TC11 (first contact), which is a signal contact (communication request contact) shown in Fig. 1. The communication request signal / WAKE is pulled up to the camera microcomputer power supply VMCU_C via a resistor. The camera control circuit A101 can detect a communication request from the accessory 200 by detecting a change (falling edge) in the communication request signal / WAKE.

[0081] SDA connected to communication contact TC12 (third contact) and SCL connected to communication contact TC13 (second contact) are signals for communication by the I2C (Inter-Integrated Circuit) communication method (hereinafter referred to as I2C communication), which is a first communication method, with the camera control circuit A101 acting as the communication master. SDA is a data signal, and SCL is a clock signal. SDA and SCL are open-drain signals pulled up to the camera microcontroller power supply VMCU_C, and in this embodiment the communication frequency is 100 kbps.

[0082] In I2C communication, both data transmission from the camera 100 and data transmission from the accessory 200 are performed via SDA. Comparing SPI communication and I2C communication, I2C communication has a slower communication speed than SPI communication. SPI communication also has a faster communication speed than I2C communication, making it suitable for communicating information with large amounts of data. Therefore, in communication between the camera 100 and accessory 200 in this embodiment, information with large amounts of data is communicated using SPI communication, and information with small amounts of data is communicated using I2C communication. For example, data is first communicated using I2C communication, and if SPI communication is possible or necessary based on this data, control can be exercised to further execute SPI communication.

[0083] Figures 19(a) and (b) show examples of I2C communication waveforms. Figure 19(a) shows an example of the waveform when the camera sends N bytes of data (DATA[1] to DATA[N]) to the accessory, and Figure 19(b) shows an example of the waveform when the camera receives N bytes of data (DATA[1] to DATA[N]) from the accessory. In Figures 19(a) and 19(b), the upper waveform is SCL and the lower waveform is SDA.

[0084] Below the SDA waveform is shown the meaning of the signal at each timing, and whether the control circuit controlling the output level of the SDA signal is the camera control circuit A101 or the accessory control circuit 201. The communication data is made up of 1-byte data and 1-bit information indicating the response. The top of the diagram shows which byte of data is in that order from the start of communication.

[0085] The details of the communication will be described later with reference to FIGS. 20 to 22, and therefore only an outline will be given in FIGS. 19(a) and 19(b).

[0086] 19(a), in the communication of the first and second bytes, the camera control circuit A101 notifies the accessory control circuit 201 of storage address information of the data to be transmitted. In the communication of the third to (N+2)th bytes, the camera control circuit A101 transmits N bytes of data (DATA[ADDRESS] to DATA[ADDRESS+N]) to the accessory control circuit 201.

[0087] 19(b), in the communication of the first and second bytes, the camera control circuit A101 notifies the accessory control circuit 201 of storage address information for the data to be received. In the communication of the third to (N+3)th bytes, the camera control circuit A101 receives N bytes of data (DATA[ADDRESS] to DATA[ADDRESS+N]) from the accessory control circuit 201.

[0088] The flowchart in FIG. 20 shows the processing performed by the camera control circuit A101 when transmitting N bytes of data from the camera control circuit A101 to the accessory control circuit 201.

[0089] In S3001, the camera control circuit A101 stores a numerical value indicating the number of bytes to be transmitted in the internal variable N. For example, when transmitting 3 bytes, 3 is stored. In this embodiment, 3 is stored.

[0090] In S3002, the camera control circuit A101 changes SDA to Lo level while SCL is at Hi level (START condition), thereby notifying the accessory control circuit 201 of the start of communication.

[0091] In S3003, the camera control circuit A101 sets the upper 7 bits of the transmission data to slave address information indicating the slave address of the accessory control circuit 201. In this embodiment, the slave address of the accessory control circuit 201 is assumed to be 1010000 in binary.

[0092] In S3004, the camera control circuit A101 sets information indicating WRITE communication in the lowest 1 bit of the transmission data. Setting this bit to 0 indicates WRITE communication.

[0093] In S3005, the camera control circuit A101 transmits to the accessory control circuit 201 the data (10100000 in binary, 0xA0 in hexadecimal) set as transmission data in S3003 and S3004.

[0094] In S3006, the camera control circuit A101 outputs SCL for one clock after transmitting one byte of data, and checks the signal level of SDA. If the signal level of SDA is Lo, it is determined to be a data reception acknowledgement (ACK) from the accessory control circuit 201, and the process proceeds to S3007. On the other hand, if the signal level of SDA is Hi, it is determined that the accessory control circuit 201 has not received the data correctly, and the process proceeds to S3014.

[0095] In S3007, the camera control circuit A101 sets, as transmission data, information on the storage address (start address information) of the data to be transmitted to the accessory control circuit 201. In this embodiment, the size of the start address information is 1 byte, and the value is 0x00.

[0096] In S3008, the camera control circuit A101 transmits the set 1-byte start address information (value 0x00) to the accessory control circuit 201.

[0097] In S3009, the camera control circuit A101 outputs SCL for one clock after transmitting one byte of start address information data, and checks the signal level of SDA. If the signal level of SDA is Lo, it is determined to be a data reception acknowledgement (ACK) from the accessory control circuit 201, and the process proceeds to S3010. On the other hand, if the signal level of SDA is Hi, it is determined that the accessory control circuit 201 has not received the data correctly, and the process proceeds to S3014.

[0098] In S3010, the camera control circuit A101 stores 1 in the internal variable M. The internal variable M is a variable for counting the number of pieces of transmitted data.

[0099] In S3011, the camera control circuit A101 outputs one byte of SCL and changes SDA to a desired signal level while SCL is Lo, thereby transmitting one byte of data to the accessory control circuit 201. Here, the start address information is 0x00 and the internal variable M is 1, so one byte of data corresponding to address 0x00 is transmitted.

[0100] In S3012, the camera control circuit A101 outputs SCL for one clock after transmitting one byte of data, and checks the signal level of SDA. If the signal level of SDA is Lo, it is determined to be a data reception acknowledgement (ACK) from the accessory control circuit 201, and the process proceeds to S3013. On the other hand, if the signal level of SDA is Hi, it is determined that the accessory control circuit 201 has not received the data correctly, and the process proceeds to S3014.

[0101] In S3013, the camera control circuit A101 checks whether the internal variable M has the same value as the internal variable N. If the internal variable M has the same value as the internal variable N, it determines that transmission of all data has been completed and proceeds to S3014. If the internal variable M does not have the same value as the internal variable N, it determines that there is still data remaining to be transmitted and proceeds to S3015.

[0102] In S3015, the camera control circuit A101 adds 1 to the internal variable M and returns to S3011.

[0103] In this way, after returning to S3011, the camera control circuit A101 sequentially increments the address of the data to be transmitted and transmits one byte of data corresponding to each address. In this way, by repeatedly transmitting one byte of data in the processing of S3013 until the internal variable M and the internal variable N have the same value, the camera control circuit A101 transmits N bytes of data to the accessory control circuit 201. When the internal variable N is set to 3 as in this embodiment, 3 bytes of data can be transmitted.

[0104] In S3014, the camera control circuit A101 changes SDA to Hi level while SCL is at Hi level (STOP condition), thereby notifying the accessory control circuit 201 of the end of communication.

[0105] The flowchart in FIG. 21 shows the processing performed by the camera control circuit A101 when the camera control circuit A101 receives N bytes of data from the accessory control circuit 201.

[0106] In S3101, the camera control circuit A101 stores a numerical value indicating the number of bytes to be received in the internal variable N. For example, if 3 bytes are to be received, 3 is stored. In this embodiment, 3 is stored.

[0107] In S3102 to S3106, the camera control circuit A101 performs the same processing as in S3002 to S3006, respectively, and therefore a description thereof will be omitted.

[0108] In S3107, the camera control circuit A101 sets, as transmission data, information on the storage address (start address information) of the data received from the accessory control circuit 201. In this embodiment, the size of the start address information is 1 byte, and the value is 0x00.

[0109] In S3108, the camera control circuit A101 transmits the set 1-byte start address information (value 0x00) to the accessory control circuit 201.

[0110] In S3109, the camera control circuit A101 outputs SCL for one clock after transmitting one byte of start address information data, and checks the signal level of SDA. If the signal level of SDA is Lo, it is determined to be a data reception acknowledgement (ACK) from the accessory control circuit 201, and the process proceeds to S3110. On the other hand, if the signal level of SDA is Hi, it is determined that the accessory control circuit 201 has not received the data normally, and the process proceeds to S3122.

[0111] In S3110, the camera control circuit A101 changes SDA to Lo level while SCL is at Hi level, as in S3102, and notifies the accessory control circuit 201 of a START condition.

[0112] In S3111, the camera control circuit A101 sets the upper 7 bits of the transmission data to slave address information indicating the slave address of the accessory control circuit 201. In this embodiment, the slave address of the accessory control circuit 201 is assumed to be 1010000 in binary.

[0113] In S3112, the camera control circuit A101 sets information indicating READ communication in the lowest 1 bit of the transmission data. Setting this bit to 1 indicates READ communication.

[0114] In S3113, the camera control circuit A101 transmits to the accessory control circuit 201 the data (10100001 in binary, 0xA1 in hexadecimal) set as transmission data in S3003 and S3004.

[0115] In S3114, the camera control circuit A101 outputs SCL for one clock after transmitting one byte of data, and checks the signal level of SDA. If the signal level of SDA is Lo, it is determined to be a data reception acknowledgement (ACK) from the accessory control circuit 201, and the process proceeds to S3115. On the other hand, if the signal level of SDA is Hi, it is determined that the accessory control circuit 201 has not received the data normally, and the process proceeds to S3122.

[0116] In S3115, the camera control circuit A101 stores 1 in the internal variable M. The internal variable M is a variable for counting the number of pieces of received data.

[0117] In S3116, the camera control circuit A101 outputs one byte of SCL and reads the SDA signal level at the timing when SCL changed from Lo to Hi. This makes it possible to receive one byte of data from the accessory control circuit 201. The received one byte of data can be stored in the volatile memory 125 as data corresponding to address 0x00, or can be used for predetermined processing.

[0118] In S3117, the camera control circuit A101 determines whether 1 byte of data has been received normally. If it has been received normally, the process proceeds to S3118. If it has not been received normally, the process proceeds to S3119.

[0119] In S3118, the camera control circuit A101 checks whether the internal variable M has the same value as the internal variable N. If the internal variable M has the same value as the internal variable N, it determines that reception of all data has been completed and proceeds to S3119. If the internal variable M does not have the same value as the internal variable N, it determines that received data still remains and proceeds to S3120.

[0120] In S3120, the camera control circuit A101 outputs one byte of SCL and controls SDA to the Lo level, thereby sending a data reception acknowledgement (ACK) to the accessory control circuit 201 and notifying it that data communication will continue.

[0121] In S3121, the camera control circuit A101 adds 1 to the internal variable M and returns to S3116.

[0122] In this way, after returning to S3116, the camera control circuit A101 sequentially increments the address of the data to be received and receives one byte of data corresponding to each address. In this way, by repeatedly receiving one byte of data in the processing of S3118 until the internal variable M and the internal variable N have the same value, the camera control circuit A101 receives N bytes of data from the accessory control circuit 201. If the internal variable N is set to 3 as in this embodiment, three bytes of data can be received.

[0123] In S3119, the camera control circuit A101 outputs one byte of SCL and controls SDA to Hi level, thereby notifying the accessory control circuit 201 that data communication has been completed (NACK).

[0124] In S3122, the camera control circuit A101 changes SDA to Hi level while SCL is at Hi level (STOP condition), thereby notifying the accessory control circuit 201 of the end of communication.

[0125] The flowchart in Figure 22 shows the processing performed by the accessory control circuit 201 when the camera control circuit A101 transmits N bytes of data to the accessory control circuit 201 and when the camera control circuit A101 receives N bytes of data from the accessory control circuit 201.

[0126] In S3201, the accessory control circuit 201 waits for SDA to change to Lo level (START condition) while SCL is at Hi level. If the accessory control circuit 201 detects the START condition, the process proceeds to S3202.

[0127] In S3202, the accessory control circuit 201 stores 0 in the internal variable M. The internal variable M is a variable for counting the number of transmitted and received data.

[0128] In S3203, the accessory control circuit 201 receives the 1-byte data transmitted from the camera control circuit A101.

[0129] In S3204, the accessory control circuit 201 determines whether the upper 7 bits of the 1-byte data received in S3203 match the slave address (0x50 in this embodiment) of the accessory control circuit 201. If it matches the slave address of the accessory control circuit 201, proceed to S3205. If it does not match the slave address of the accessory control circuit 201, proceed to S3221.

[0130] In S3205, the accessory control circuit 201 controls SDA to a Low level for the next SCL clock output after receiving one byte, thereby sending a data reception acknowledgement (ACK) to the camera control circuit A101.

[0131] In S3206, the accessory control circuit 201 determines the type of data for the next 1-byte communication based on the lowest 1 bit of the 1-byte data received in S3203. If the lowest 1 bit of data is 0, it determines that the data for the next 1-byte communication is start address information from the camera control circuit A101 to the accessory control circuit 201, and proceeds to S3207. If the lowest 1 bit of data is 1, it determines that the data for the next 1-byte communication is transmission data from the accessory control circuit 201 to the camera control circuit A101, and proceeds to S3209.

[0132] In S3207, the accessory control circuit 201 receives one byte of data transmitted from the camera control circuit A101. The received one byte of data is information indicating the address where data to be transmitted and received in subsequent communications is stored. In this embodiment, as described with reference to FIGS. 20 and 21, the start address information is assumed to be 0x00.

[0133] On the other hand, in S3209, the accessory control circuit 201 uses, as the start address information, address information that has been stored in advance in the accessory control circuit 201 or address information that has been notified in advance from the camera control circuit A101.

[0134] In S3208, if the accessory control circuit 201 determines that one byte of data has been received successfully, it proceeds to S3210. If it determines that one byte of data has not been received successfully, it proceeds to S3221.

[0135] In S3210, the accessory control circuit 201 controls SDA to Low level for the next SCL clock output after receiving one byte of data, thereby sending a data reception acknowledgement (ACK) to the camera control circuit A101.

[0136] In S3211, the accessory control circuit 201 checks whether SDA has changed to a low level (START condition) while SCL is at a high level. If a START condition is detected, the accessory control circuit 201 determines that the next 1-byte of data to be communicated is data to be transmitted from the camera control circuit A101 to the accessory control circuit 201, and is data indicating a slave address and communication type, and proceeds to S3212. If a START condition is not detected, the accessory control circuit 201 determines that the next 1-byte of data to be communicated is data information to be received by the accessory control circuit 201 from the camera control circuit A101, and proceeds to S3216.

[0137] In S3212, the accessory control circuit 201 receives the 1-byte data transmitted from the camera control circuit A101.

[0138] In S3213, the accessory control circuit 201 determines whether the upper 7 bits of the 1-byte data received in S3212 match the slave address (0x50 in this embodiment) of the accessory control circuit 201. If it matches the slave address of the accessory control circuit 201, proceed to S3214. If it does not match the slave address of the accessory control circuit 201, proceed to S3221.

[0139] In S3214, the accessory control circuit 201 determines the type of data for the next 1-byte communication based on the lowest 1 bit of the 1-byte data received in S3203. If the lowest 1 bit of data is 0, proceed to S3221. If the lowest 1 bit of data is 1, determine that the data for the next 1-byte communication is transmission data from the accessory control circuit 201 to the camera control circuit A101, and proceed to S3215.

[0140] In S3215, the accessory control circuit 201 controls SDA to be at the Lo level for the next SCL clock output after receiving one byte, thereby sending a data reception acknowledgement (ACK) to the camera control circuit A101.

[0141] In S3222, the accessory control circuit 201 transmits to the camera control circuit A101 one byte of data corresponding to the start address information received from the camera control circuit A101 in S3207 or the start address information determined in S3209.

[0142] In S3223, the accessory control circuit 201 adds 1 to the internal variable M and proceeds to S3224.

[0143] In S3224, the accessory control circuit 201 checks the signal level of SDA after transmitting one byte of data. If the signal level of SDA is Hi, it is determined that this is a notification (NACK) that the camera control circuit A101 has finished receiving all data, and the process proceeds to S3225. On the other hand, if the signal level of SDA is Hi, it is determined that the camera control circuit A101 is still requesting data transmission from the accessory control circuit 201, and the process returns to S3222. In this way, after returning to S3222, the accessory control circuit 201 sequentially increments the address of the data to be transmitted and transmits one byte of data corresponding to each address. In this way, by repeatedly transmitting one byte of data until a NACK is notified from the camera control circuit A101 in the process of S3224, the accessory control circuit 201 transmits N bytes of data to the camera control circuit A101.

[0144] In S3225, the accessory control circuit 201 waits for a STOP condition in which SDA changes to Hi level while SCL is at Hi level. When the accessory control circuit 201 detects the STOP condition, it ends communication.

[0145] Meanwhile, in S3216, the accessory control circuit 201 receives one byte of data, and stores the one byte of data in a non-volatile memory (not shown) as data corresponding to the start address information received from the camera control circuit A101 in S3207, or uses the data for predetermined processing.

[0146] In S3217, the accessory control circuit 201 adds 1 to the internal variable M and proceeds to S3218.

[0147] In S3218, if the accessory control circuit 201 determines that one byte of data has been received successfully, it proceeds to S3219. If it determines that one byte of data has not been received successfully, it proceeds to S3221.

[0148] In S3219, the accessory control circuit 201 controls SDA to be at the Lo level for the next SCL clock output after receiving one byte, thereby sending a data reception acknowledgement (ACK) to the camera control circuit A101.

[0149] In S3230, the accessory control circuit 201 checks whether a STOP condition, in which SDA changes to Hi level while SCL is at Hi level, has been detected. If the accessory control circuit 201 detects a STOP condition, it ends communication. On the other hand, if the accessory control circuit 201 does not detect a STOP condition, it determines that the camera control circuit A101 will continue to send data to the accessory control circuit 201, and returns to S3216.

[0150] In this way, after returning to S3216, the accessory control circuit 201 sequentially increments the address of the data to be received and receives one byte of data corresponding to each address. By repeatedly receiving one byte of data in this way until a STOP condition is notified in S3220, the accessory control circuit 201 receives N bytes of data from the camera control circuit A101.

[0151] Thus, the camera connection unit 141 includes a contact TC12 for a data signal of the I2C communication system and a contact TC13 for a clock signal of the I2C communication system, which is arranged on one side of the data signal contact (adjacent on one side).The camera connection unit 141 further includes a contact TC11 for a second input signal, a contact TC10 for an input selection signal of the SPI communication system, a contact TC09 for receiving in the SPI communication system, a contact TC08 for transmitting in the SPI communication system, a contact TC07 for a clock signal of the SPI communication system, a contact TC06 for a first input signal, and a contact TC05 for an output signal, which are arranged on the other side of the data signal contact TC12 (in order from the position adjacent on the other side).

[0152] The accessory 200 stores accessory information in a non-volatile memory (not shown). The accessory information is information that allows the camera 100 to identify the type of accessory 200 and specifications related to communication and operation (function). FIG. 5 shows an example of accessory information. The accessory information is mapped to a memory space of addresses 0x00 to 0x0F, and the accessory information can be read from the accessory 200 via I2C communication. Details of the accessory information will be described later. Note that in the I2C communication of this embodiment, a checksum value for the read data is added as the final data of the communication.

[0153] 1, the FNC1 signal connected to TC14, the FNC2 signal connected to TC15, the FNC3 signal connected to TC16, and the FNC4 signal connected to TC17 are function signals whose functions can be changed according to the type of attached accessory 200. For example, if accessory 200 is a microphone device, the signal communicated via TC15 is a signal related to audio data, and if accessory 200 is a strobe device, the signal communicated via TC14 is a signal notifying the timing of light emission.

[0154] Note that signals realizing different functions may be communicated via the same contact depending on the type of attached accessory. For example, if accessory 200 is an accessory other than lighting, a synchronization signal for controlling timing different from the light emission timing may be communicated via TC14. TC14 to TC17 correspond to function signal contacts. Communication using at least one of the function signal contacts is also referred to as function signal communication. Function signal communication can be performed in parallel with I2C communication and SPI communication, with timing independent of I2C communication and SPI communication.

[0155] The accessory type here refers to the microphones, lighting equipment, etc. mentioned above. Accessories that achieve the same purpose, such as lighting equipment with different performance capabilities, are considered to be of the same accessory type. Accessories that achieve different purpose, such as microphones and lighting equipment, are considered to be of different accessory types. Functional signal communication is performed based on information acquired through I2C or SPI communication. TC18, the second ground contact, is also connected to GND and, like TC04, serves as the reference potential for the camera 100 and accessory 200. The differential signal D2N connected to TC19 and the differential signal D2P connected to TC20 are data communication signals that form a pair for data communication and are connected to the camera control circuit B102. For example, USB communication can be performed via TC19 and TC20.

[0156] TC21 is connected to GND and serves not only as a reference potential contact but also as a contact for controlling the wiring impedance of differential signals D2N and D2P. TC21 corresponds to the fourth ground contact. Contacts TC01, TC04, TC06, TC18, and TC21 are connected to, for example, the GND portion of a flexible substrate, and the GND portion of the flexible substrate is fixed with screws or the like to a metal member that serves as the GND level of camera 100. Examples of the metal member that serves as the GND level include an engagement member that engages with accessory 200 in the accessory shoe portion and a base plate (not shown) inside camera 100.

[0157] In this embodiment, the attachment detection contact TC06, to which the accessory attachment detection signal / ACC_DET is connected, is located next to the contact (first clock contact) TC07 that transmits the clock signal SCLK (first clock signal). Generally, noise (clock noise) caused by potential fluctuations in the clock signal is transmitted to contacts adjacent to the clock signal contact, which can cause malfunction. This effect is particularly significant in a configuration with a large number of contacts and a short distance between the contacts, as in this embodiment. Therefore, by locating the attachment detection contact TC06 next to the SCLK contact TC07, the effect of clock noise can be suppressed.

[0158] The accessory attachment detection signal / ACC_DET is pulled up before the accessory is attached, but is set to GND potential after the accessory is attached. On the other hand, the SCLK contact TC07, which transmits the clock signal, does not transmit the clock signal before the accessory is attached, so its potential does not fluctuate, but it transmits the clock signal only after the accessory is attached, so its potential fluctuates.

[0159] When the SCLK contact TC07 transmits the clock signal, the attachment detection contact TC06 is at GND potential. Therefore, even if the attachment detection contact TC06 is subjected to clock noise, the potential of the control circuits of the camera 100 and accessory 200 is unlikely to fluctuate, preventing malfunction. In addition, the transmission of clock noise to positions farther away than the attachment detection contact TC06 can be suppressed. As a result, there is no need to provide a GND terminal, and the effects of clock noise can be suppressed without increasing the number of contacts.

[0160] In addition, SCL (second clock signal) is also transmitted as a clock signal to contact (second clock contact) TC13. However, the SCLK transmitted to SCLK contact TC07 has a higher frequency than SCL, and more clock noise is generated from the SCLK contact TC07 than from the SCL contact TC13. For this reason, placing the attachment detection contact TC06 next to the SCLK contact TC07 rather than next to the SCL contact TC13 is more effective in preventing malfunctions due to clock noise.

[0161] In addition to the difference in frequency, the SCL transmitted through the SCL contact TC13 is a clock signal conforming to the I2C communication standard, and voltage fluctuations on the signal line are driven by an open-drain connection. On the other hand, the SCLK transmitted through the SCLK contact TC07 is a clock signal conforming to the SPI communication standard, and voltage fluctuations on the signal line are driven by a CMOS output. For this reason, the voltage fluctuation edges of the SCL contact TC13 tend to be gentler than those of the SCLK contact TC07, making it less likely to generate clock noise. Therefore, placing the attachment detection contact TC06 next to the SCLK contact TC07 rather than next to the SCL contact TC13 is more effective in preventing malfunctions caused by clock noise.

[0162] Additionally, differential signals D1N and D1P may also be transmitted as a pair to the first and second differential signal contacts TC19 and TC20 to transmit clock signals. In such cases, a clock signal (third clock signal) with a higher frequency than the SCLK contact TC07 and SCL contact TC13 may be transmitted. However, because the differential signals D1N and D1P are paired signals, they emit less clock noise than the SCLK contact TC07 and SCL contact TC13, which transmit single-ended signals. For this reason, placing the attachment detection contact TC06 next to the SCLK contact TC07 rather than next to the first and second differential signal contacts TC19 and TC20 is more effective in preventing malfunctions due to clock noise.

[0163] The contact (first data contact) TC08, located next to the SCLK contact TC07 on the opposite side of the attachment detection contact TC06, transmits MOSI (first data signal). Because MOSI is a data signal, it appears to be susceptible to clock noise. However, because MOSI is a data signal that conforms to the same SPI communication standard as the clock signal transmitted by the SCLK contact TC07, the timing of its potential fluctuations is synchronized with the clock signal, making it less susceptible to clock noise. For this reason, contact TC08 does not need to be fixed to GND potential, and can be used as the MOSI contact.

[0164] The accessory 200 has a battery 205 and receives power from the battery 205, as well as power from the camera 100 via the camera connection unit 141 and the accessory connection unit 211. An accessory control circuit 201 serving as accessory processing means in the accessory 200 is a circuit that controls the entire accessory 200, and is configured by a processor (microcomputer) such as a CPU. The accessory control circuit 201 executes various controls and processes according to a computer program.

[0165] The accessory power supply circuit 202 is a circuit that generates power to be supplied to each circuit of the accessory 200, and is composed of a DC / DC converter circuit, an LDO, a charge pump circuit, etc. The accessory control circuit 201 is constantly supplied with a voltage of 1.8V generated by the accessory power supply circuit 202 as the accessory microcontroller power supply VMCU_A. Note that the voltage generated by the accessory power supply circuit 202 may be a value other than 1.8V. By controlling the accessory power supply circuit 202, on / off control of the power supply to each circuit of the accessory 200 is performed.

[0166] Charging circuit (powered means) 204 is a circuit for charging battery 205 using power supplied from camera 100. When accessory control circuit 201 determines that sufficient power is being supplied from camera 100 to perform the charging operation, it controls charging circuit 204 to charge battery 205. Note that although this embodiment describes a case where battery 205 is attached to accessory 200, accessory 200 may also operate without battery 205 attached and with only power supplied from camera 100 to accessory power supply circuit (powered means) 202. In this case, charging circuit 204 is not necessary.

[0167] The differential communication circuit 207 is a circuit for performing differential communication with the camera 100, and can transmit and receive data to and from the camera 100. The external communication IF circuit 208 is an IF circuit for performing data communication with an external device (not shown), and is an Ethernet communication IF, a wireless LAN communication IF, a public network communication IF, etc. The accessory control circuit 201 controls the differential communication circuit 207 and the external communication IF circuit 208 to transmit data received from the camera 100 to the external device and transmit data received from the external device to the camera 100.

[0168] The functional circuit 206 is a circuit having different functions depending on the type of accessory 200. For example, if the accessory 200 is a strobe device, the functional circuit 206 is a light emission circuit, a charging circuit, etc. If the accessory 200 is a microphone device, the functional circuit 206 is an audio codec circuit, a microphone circuit, etc.

[0169] The external connection terminal 209 is a connector terminal for connecting to an external device, and in this embodiment is a USB TYPE-C connector. The connection detection circuit 210 is a circuit for detecting that an external device has been connected to the external connection terminal 209. The accessory control circuit 201 can detect the connection of an external device to the external connection terminal 209 by receiving an output signal from the connection detection circuit 210.

[0170] The power switch 203 is a switch that is operated by the user to turn on and off the power (i.e., operation) of the accessory 200. The accessory control circuit 201 can detect the on position / off position by reading the signal level of the terminal to which the power switch 203 is connected.

[0171] The operation switch 212 is a switch operated by the user to give various instructions to the accessory 200 or to make various settings, and includes a button, a cross key, a slide switch, a dial switch, a touch sensor, etc. When the operation switch 212 is operated, the accessory control circuit 201 detects the operation and executes a predetermined process according to the operation.

[0172] The accessory connection unit 211 is a connector for making an electrical connection with the camera 100 via 21 contacts TA01 to TA21 arranged in a row. The contacts TA01 to TA21 are arranged in this order from one end to the other in the arrangement direction.

[0173] TA01 is connected to GND and serves not only as a reference potential contact but also as a contact to control the wiring impedance of the differential signals D1N and D1P. TA01 corresponds to the third ground contact.

[0174] The differential signal D1N connected to TA02 and the differential signal D1P connected to TA03 are data communication signals that form a pair to perform data communication, and are connected to a differential communication circuit 207. TA02, TA03, and TA07 to TA10, TA12 to TA17, TA19, and TA20, which will be described later, are communication contacts.

[0175] TA04 as a first ground contact is connected to GND and serves as a reference potential contact between the camera 100 and the accessory 200. TA04 is arranged further outward in the arrangement direction of the contacts than TA05, which will be described next.

[0176] The accessory power supply circuit 202 and the charging circuit 204 are connected to the power contact TA05, and the accessory power supply VACC supplied from the camera 100 is connected to the power contact TA05.

[0177] TA06 (fourth contact) as an attachment detection contact is directly connected to GND. When the accessory 200 is attached to the camera 100, the accessory control circuit 201 sets the accessory attachment detection signal / ACC_DET to Lo level (GND potential) as an active potential. This allows the camera 100 to detect that the accessory 200 is attached.

[0178] The communication contacts SCLK connected to TA07, MOSI connected to TA08, MISO connected to TA09, and CS connected to TA10 are signals that allow the accessory control circuit 201 to function as a communication slave and perform SPI communication.

[0179] A communication request signal / WAKE is connected to TA11 (first contact), which is a signal contact (communication request contact), for requesting communication from the accessory control circuit 201 to the camera 100. When the accessory control circuit 201 determines that communication with the camera 100 is necessary, it changes the communication request signal / WAKE from Hi level to Lo level, thereby making a communication request to the camera 100.

[0180] When the camera control circuit 101 supplies power to the accessory 200 via TC5 in response to detecting that the accessory 200 is attached, the accessory control circuit 201 notifies the camera control circuit 101 that it has received power supply by changing the signal level (potential) of the communication request signal / WAKE from Hi level to Lo level.

[0181] The accessory control circuit 201 can notify the camera 100 that a cause for the accessory 200 to communicate with the camera 100 has occurred by changing the signal level (electric potential) of the communication request signal / WAKE from Hi level to Lo level even without a request from the camera. With this configuration, the camera control circuit 101 can omit the operation of periodically checking whether a cause for the accessory 200 to communicate has occurred by polling. Furthermore, when a cause for communication has occurred, the accessory 200 can notify the camera 100 of that fact in real time.

[0182] SDA connected to communication contact TA12 (third contact) and SCL connected to communication contact TA13 (second contact) are signals for the accessory control circuit 201 to perform I2C communication as a communication slave.

[0183] Thus, the accessory connection unit 211 includes a contact TA12 for a data signal of the I2C communication system and a contact TA13 for a clock signal of the I2C communication system, which is arranged on one side of the data signal contact (adjacent on one side).The accessory connection unit 211 further includes a contact TA11 for a second input signal, a contact TA10 for an input selection signal of the SPI communication system, a transmitting contact TA09 for the SPI communication system, a receiving contact TA08 for the SPI communication system, a contact TA07 for a clock signal of the SPI communication system, a contact TA06 for a first input signal, and a contact TA06 for an output signal, which are arranged on the other side of the data signal contact TAB12 (in order from the position adjacent on the other side).

[0184] The FNC1 signal connected to communication contacts (functional signal contacts) TA14, the FNC2 signal connected to TA15, the FNC3 signal connected to TA16, and the FNC4 signal connected to TA17 are functional signals whose functions can be changed according to the type of accessory 200. For example, if accessory 200 is a microphone device, the signal will be related to audio data, and if accessory 200 is a strobe device, the signal will be a signal notifying the timing of light emission.

[0185] TA18 as a second ground contact is also connected to GND, and like TA04, it is a contact point for the reference potential between the camera 100 and the accessory 200. The differential signal D2N connected to TA19 and the differential signal D2P connected to TA20 are data communication signals that form a pair to perform data communication, and are connected to the external connection terminal 209.

[0186] TA21 is connected to GND and serves not only as a reference potential contact but also as a terminal to control the wiring impedance of the differential signals D2N and D2P. TA21 corresponds to the fourth ground contact.

[0187] The contacts TA01, TA04, TA06, TA18, and TA21 are connected to, for example, a GND portion of a flexible substrate, and the GND portion of the flexible substrate is fixed with screws or the like (not shown) to a metal member that serves as the GND level of the accessory 200. Examples of the metal member that serves as the GND level include a shoe mounting leg that engages with the accessory shoe portion of the camera 100 and a base plate (not shown) inside the accessory 200.

[0188] 6 shows a sequence of processing that is performed when accessory 200 is attached to camera 100. Here, an overview of the processing of camera 100 (camera control circuits A101, B102) and accessory 200 (accessory control circuit 201) will be described, and details will be given later.

[0189] When the accessory 200 is attached to the camera 100, the accessory attachment detection signal / ACC_DET goes low. This causes the camera control circuit A101 to determine that the accessory 200 is attached to the camera 100. Having determined that the accessory 200 is attached, the camera control circuit A101 sets the power supply control signal CNT_VACC1 to high level in order to turn on the output of the accessory power supply circuit A131. The accessory power supply circuit A131 outputs the accessory power supply VACC in response to the power supply control signal CNT_VACC1 going high.

[0190] The accessory power supply circuit 202, which receives power from VACC, generates a power supply VMCU_A for the accessory control circuit 201. This starts up the accessory control circuit 201. The started accessory control circuit 201 initializes each block in the accessory 200. After that, when the accessory control circuit 201 becomes able to communicate with the camera 100, it sets the communication request signal / WAKE to Lo level.

[0191] When the communication request signal / WAKE becomes low level, the camera control circuit A101 detects that the accessory 200 is ready for communication. The camera control circuit A101 requests the accessory 200 to communicate accessory information via I2C communication. Upon receiving the communication request for accessory information, the accessory control circuit 201 transmits the accessory information to the camera control circuit A101. After transmitting the accessory information, the accessory control circuit 201 sets the communication request signal / WAKE to high level.

[0192] Based on the received accessory information, the camera control circuit A101 determines whether the attached accessory can be controlled, and turns on the accessory power supply circuit B132. The camera control circuit A101 then performs various settings for the camera 100, and when this is complete, notifies the camera control circuit B102 of the accessory information.

[0193] Based on the notified accessory information, the camera control circuit B102 notifies the accessory 200 of a control command (accessory control communication) through SPI communication and performs control corresponding to the function signal (function signal control). In other words, it controls the accessory 200 through SPI communication.

[0194] The accessory control circuit 201 responds to control commands sent from the camera 100 via SPI communication, and performs operations according to function signals.

[0195] Here, the accessory information exemplified in Fig. 5 will be described. Data D7-D0 at address 0x00 is information indicating the type of accessory (hereinafter referred to as accessory type information). Fig. 7 shows an example of accessory type information. For example, 0x81 indicates a strobe device, 0x82 an interface conversion adapter device, 0x83 a microphone device, and 0x84 a multi-accessory connection adapter device for attaching multiple accessory devices to the camera 100.

[0196] An adapter device is an intermediate accessory that is attached between the camera 100 and an accessory such as a flash device or a microphone device. An interface conversion adapter device is an adapter device that converts the interface to make the camera 100 and the accessory compatible when the interface of the camera 100 and the interface of the accessory are different. A multi-accessory connection adapter device is an adapter device that can attach multiple accessories.

[0197] 5 is information (hereinafter referred to as accessory model information) that indicates the model (type) of the accessory 200. The accessory type information described above and this information make it possible to identify the type and model of the accessory.

[0198] The D7-D0 data at address 0x02 is information indicating the firmware version of the accessory 200.

[0199] The data D7-D6 at address 0x03 is specification information (hereinafter referred to as power-off power supply necessity information) indicating whether or not to request the supply of accessory power supply VACC (power supply) to accessory 200 when camera 100 is in a power-off state (first power saving state) with a power switch (not shown) turned off. When this information is 0, power supply is not required, and when it is 1, power supply from accessory power supply circuit A131 is requested. When it is 2, power supply from accessory power supply circuit B132 is requested.

[0200] The D5-D4 data at address 0x03 is specification information (hereinafter referred to as auto power off power supply necessity information) that indicates whether or not the camera 100 requests the supply of accessory power VACC to the accessory 200 when the camera 100 enters a power saving state (second power saving state: hereinafter referred to as the auto power off state) due to the auto power off function. The camera 100 has an auto power off function that automatically turns off the power when no operation is performed for a predetermined period of time in order to reduce power consumption. When this information is 0, it indicates that power supply is not required, when it is 1, it indicates a request for power supply from the accessory power supply circuit A131, and when it is 2, it indicates a request for power supply from the accessory power supply circuit B132.

[0201] The D3-D2 data at address 0x03 is specification information indicating whether the accessory 200 is equipped with a battery 205. When this information is 0, it indicates that a battery is not equipped, and when this information is 1, it indicates that a battery is equipped.

[0202] The D1-D0 data at address 0x03 is specification information (hereinafter referred to as charging compatibility information) that indicates whether the accessory 200 has a function for charging the battery 205. When this information is 0, it indicates that the accessory does not have a charging function, and when this information is 1, it indicates that the accessory has a charging function.

[0203] The D7-D0 data at address 0x04 is specification information indicating the power required by the accessory power supply VACC to which the accessory 200 is supplied by the camera 100. For example, multiplying this information by 10 indicates a current value, so that 10 indicates 100 mA, and 100 indicates 1 A. As a method for reducing the amount of information in this information, this information may be simplified and associated with a current value. For example, 0 indicates 100 mA, 1 indicates 300 mA, 3 indicates 450 mA, and 4 indicates 600 mA.

[0204] The D7 data at address 0x05 is specification information indicating whether the accessory 200 is in firmware update mode. If this information is 0, it indicates that the accessory is not in firmware update mode, and if this information is 1, it indicates that the accessory is in firmware update mode.

[0205] The D6 data at address 0x05 is specification information indicating whether or not the accessory 200 has a firmware update function. If this information is 0, it indicates that the accessory does not have a firmware update function, and if it is 1, it indicates that the accessory has a firmware update function.

[0206] The D5-D4 data at address 0x05 is specification information indicating whether or not operation is permitted when the accessory 200 is attached to an intermediate accessory. If this information is 0, operation is not permitted, and if it is 1, operation is permitted.

[0207] The D3-D2 data at address 0x05 is specification information indicating whether the accessory 200 requires the camera 100 to confirm that an intermediate accessory is attached when the camera 100 starts up. If this information is 0, confirmation is not required, and if it is 1, confirmation is required.

[0208] The D1-D0 data at address 0x05 is specification information indicating whether the accessory 200 supports command notification via I2C communication. If this information is 0, it indicates that command notification is not supported, and if it is 1, it indicates that command notification is supported.

[0209] The D5-D4 data at address 0x06 is specification information indicating a communication request cause acquisition method (used communication method: hereinafter referred to as cause acquisition method), which is a communication method that can be used to notify the camera 100 of the cause of a communication request after the accessory 200 has notified the camera 100 of a communication request signal / WAKE. If this information is 0, it indicates that the I2C communication method is the cause acquisition method, if it is 1, it indicates that the SPI communication method is the cause acquisition method, and if it is 2, it indicates that both the I2C communication method and the SPI communication method are the cause acquisition methods.

[0210] The D3-D0 data at address 0x06 is specification information indicating whether the accessory 200 has functions corresponding to the FNC1 signal (function signal 1), the FNC2 signal (function signal 2), the FNC3 signal (function signal 3), and the FNC4 signal (function signal 4). The D0 data corresponds to the FNC1 signal, the D1 data corresponds to the FNC2 signal, the D2 data corresponds to the FNC3 signal, and the D3 data corresponds to the FNC4 signal, and a value of 0 for each indicates that the function is not provided, and a value of 1 indicates that the function is provided.

[0211] The D7 data at address 0x0A is specification information indicating whether or not the accessory 200 requests the camera 100 to start up when it notifies the camera 100 of the communication request signal / WAKE. If this information is 0, it indicates that it requests startup, and if it is 1, it indicates that it does not request startup.

[0212] The D6-D0 data at address 0x0A is information indicating the cause of the communication request signal / WAKE that the accessory 200 notified the camera 100 of.

[0213] FIG. 8 shows examples of factors that cause a communication request signal / WAKE to occur (hereinafter also referred to as communication request factors). Here, an example is shown in which the accessory 200 is a microphone device. For example, factor number 0x00 is a number indicating that the menu call switch among the operation switches 212 has been operated (pressed). Factor number 0x01 is a number indicating that the accessory 200 has completed output control of an audio signal. Factor number 0x02 is a number indicating that the accessory 200 has completed muting of an audio signal (unmuted). In this way, in this embodiment, information on the communication request factor (number) as information related to the factor that causes a communication request signal / WAKE to occur can be notified (transmitted) from the accessory 200 to the camera 100 as one piece of accessory information.

[0214] In Figure 5, the D1 data at address 0x0C is specification information indicating the SPI communication protocol that the accessory 200 supports; if this information is 0, it indicates that it supports SPI protocol A, and if this information is 1, it indicates that it supports SPI protocol B.

[0215] The D0 data at address 0x0C is specification information indicating the control logic of the CS of the SPI communication that the accessory 200 supports; if this information is 0, it indicates that the CS is Lo active logic, and if it is 1, it indicates that the CS is Hi active logic. The D7-D0 data at address 0x0D is specification information that indicates the time required as a communication byte interval when the accessory 200 communicates using SPI protocol A and the D7 data at address 0x05 is 0, i.e., when the accessory 200 is not in firmware update mode.

[0216] The D7-D0 data at address 0x0E is specification information that indicates the time required as a communication byte interval when the accessory 200 communicates using SPI protocol A and the address 0x05D7 data is 1, i.e., when the accessory 200 is in firmware update mode.

[0217] 9(a) and (b) show the communication byte interval time (communication interval) corresponding to the data (0 to 7) at addresses 0x0D and 0x0E. Fig. 9(a) shows the communication interval for the data information at address 0x0D, and Fig. 8(b) shows the communication interval for the data at address 0x0E.

[0218] In FIG. 5, the data at address 0x0F is checksum value data indicating the sum of addresses 0x00 to 0x0E.

[0219] FIG. 10 shows the startup process that the camera control circuit A101 executes from when the accessory 200 is attached to the camera 100 until the functions of the accessory 200 are enabled.

[0220] In S401, the camera control circuit A101 monitors the signal level of the accessory attachment detection signal / ACC_DET and determines (detects) whether the accessory 200 is attached. If the signal level of / ACC_DET is Hi, the camera control circuit A101 determines that the accessory 200 is not attached and returns to S401 to again determine whether the accessory is attached. If the signal level is Lo, the camera control circuit A101 determines that the accessory 200 is attached and proceeds to S402. In S402, the camera control circuit A101 controls the power supply control signal CNT_VACC1 to Hi level to turn on the output of the accessory power supply circuit A131. Then, the process proceeds to S403. When the power supply control signal CNT_VACC1 becomes Hi level, the accessory power supply circuit A131 outputs the accessory power supply VACC.

[0221] In S403, the camera control circuit A101 monitors the signal level of the overcurrent detection signal DET_OVC to determine whether an overcurrent is flowing. If the signal level of DET_OVC is Lo, the camera control circuit A101 determines that an overcurrent is not flowing and proceeds to S404, but if the signal level is Hi, it determines that an overcurrent is flowing and proceeds to S405, where it performs error processing.

[0222] In S404, the camera control circuit A101 monitors the signal level of the communication request signal / WAKE, which is a notification signal from the accessory 200, and determines whether or not initialization of the accessory 200 is complete. If the signal level of / WAKE is Lo level (active), the camera control circuit A101 determines that initialization is complete and proceeds to S406, but if the signal level is Hi level, it determines that initialization is not complete and returns to S404, where it again determines whether initialization is complete.

[0223] In S406, the camera control circuit A101 performs I2C communication as initial communication with the accessory 200 and reads 15 bytes of accessory information. Then, the process proceeds to S407.

[0224] In S407, the camera control circuit A101 determines, based on the accessory information read out in S406, whether the attached accessory 200 is a device (compatible accessory) compatible with the camera 100. If the camera control circuit A101 determines that the attached accessory 200 is a compatible accessory, the process proceeds to S408, and if it determines that it is not a compatible accessory, the process proceeds to S409 and performs error processing.

[0225] In S408, the camera control circuit A101 controls the power supply control signal CNT_VACC2 to Hi level to turn on the output of the accessory power supply circuit B132. Then, the process proceeds to S410. When the power supply control signal CNT_VACC2 becomes Hi level, the accessory power supply circuit B132 outputs the accessory power supply VACC. In this embodiment, when both the power supply control signal CNT_VACC1 and the power supply control signal CNT_VACC2 become Hi level, the output from the accessory power supply circuit B132 is supplied to the accessory power supply VACC.

[0226] In S410, the camera control circuit A101 notifies the camera control circuit B 102 of the accessory information read out in S406, thereby completing the startup process in the camera 100 associated with the attachment of the accessory 200.

[0227] The flowchart in FIG. 11 shows the activation process that the camera control circuit B102 executes from when the accessory 200 is attached to the camera 100 until the functions of the accessory 200 are activated.

[0228] In S501, the camera control circuit B102 determines whether or not accessory information has been notified from the camera control circuit A 101. If the accessory information has not been notified, the camera control circuit B102 returns to S501 and determines whether or not it has been notified again, and if the accessory information has been notified, the process proceeds to S502.

[0229] In S502, the camera control circuit B102 performs settings for the function signals FNC1 to FNC4 based on the accessory information notified from the camera control circuit A101. For example, if it is notified that the accessory 200 is a microphone device, it sets FNC1 to function as the audio data clock signal BCLK, FNC2 to function as the audio data channel signal LRCLK, and FNC3 to function as the audio data signal SDATA. As another example, if it is notified that the accessory 200 is a strobe device, it sets FNC4 to function as the strobe light emission synchronization signal XOUT. Note that even for function signals that do not require control for the accessory 200, predetermined settings are performed so as not to interfere with the operation of the camera 100 and the accessory 200.

[0230] In S503, the camera control circuit B102 sets the control logic of the CS in the SPI communication based on the accessory information notified from the camera control circuit A101.

[0231] In S504, the camera control circuit B102 determines whether or not a predetermined event has occurred for the accessory 200. If no event has occurred, the camera control circuit B102 returns to S504 to again determine whether an event has occurred, and if an event has occurred, the camera control circuit B102 proceeds to S505.

[0232] In S505, the camera control circuit B102 determines whether the event that occurred in S504 is an event that requires SPI communication with the accessory 200. If the event requires SPI communication, the camera control circuit B102 proceeds to S506, and if not, proceeds to S507.

[0233] In S507, the camera control circuit B102 determines whether the event that occurred in S504 is an event that requires control of the accessory 200 using a function signal. If the event requires control using a function signal, the camera control circuit B102 proceeds to S508, and if not, proceeds to S509.

[0234] In S506, the camera control circuit B102 performs SPI communication with the accessory 200. For example, if the accessory 200 is a microphone device, the SPI communication performed here may include communication of an instruction to turn on the microphone, communication of an instruction to turn off the microphone, communication of an instruction to switch the microphone's sound collection directionality, and communication of an instruction to switch the microphone's equalizer function. Furthermore, if the accessory 200 is a flash device, the SPI communication may include communication to read out setting information for the flash device and communication to notify the flash device of setting information. When the SPI communication in S506 is complete, the camera control circuit B102 returns to S504 and again determines whether an event has occurred.

[0235] In S508, the camera control circuit B102 controls the accessory 200 using the function signals. For example, if the accessory 200 is a microphone device, it outputs an audio data clock signal BCLK of FNC1 and an audio data channel signal LRCLK of FNC2, and also inputs an audio data signal SDATA of FNC3. This enables the camera 100 to acquire audio data from the microphone device. Furthermore, if the accessory 200 is a strobe device, it outputs a strobe light emission synchronization signal XOUT of FNC4 at a predetermined timing. This enables the camera 100 to instruct the strobe device to emit light. Once control using the function signals is completed in this manner, the camera control circuit B102 returns to S504 and again determines whether an event has occurred.

[0236] Also, in S509, the camera control circuit B102 performs predetermined in-camera control in response to the event that occurred in S504. For example, if the accessory 200 is a microphone device, the in-camera control may include control to start or stop recording of audio data into the recording memory 126, control to perform equalizer processing on the audio data, etc. If the accessory 200 is a flash device, the in-camera control may include photometry control to accumulate and acquire light emitted by the flash device in the image sensor 122, and control to calculate an instruction value for the amount of light emitted by the flash device. Once the in-camera control is completed in this manner, the camera control circuit B102 returns to S504 and again determines whether an event has occurred.

[0237] The activation process by the camera control circuit A101 and the validation process by the camera control circuit B102 described above enable the camera 100 to control the accessory 200 attached thereto.

[0238] The flowchart in FIG. 12 shows the processing executed by the accessory control circuit 201 from when the accessory 200 is attached to the camera 100 until the accessory 200 is able to perform various functions.

[0239] In S601, the accessory control circuit 201 waits for the accessory power supply VACC from the camera 100 to be turned on. If the accessory 200 does not include a battery 205, it can detect that the accessory power supply VACC has been turned on when power is supplied to the accessory control circuit 201 and the accessory control circuit 201 itself starts operating. If the accessory 200 includes a battery 205, the accessory control circuit 201 may monitor the voltage value of the accessory power supply VACC to detect that the accessory power supply VACC has been turned on.

[0240] In S602, the accessory control circuit 201 performs predetermined initial settings, such as setting the operating frequency of the microcomputer, setting the input / output control ports of the microcomputer, initializing the timer function of the microcomputer, and initializing the interrupt function of the microcomputer. When the initial setting in S602 is completed, in S603 the accessory control circuit 201 controls the communication request signal / WAKE to Lo level, thereby notifying the camera 100 that the initial setting is completed.

[0241] In S604, the accessory control circuit 201 responds to the I2C communication from the camera 100 and transmits 15 bytes of accessory information as initial communication to the camera 100. The accessory information includes the various pieces of information shown in FIG.

[0242] When the initial communication in S604 is completed, in S605, the accessory control circuit 201 controls the communication request signal / WAKE to a Hi level.

[0243] In S606, the accessory control circuit 201 determines whether a predetermined event has occurred. If no event has occurred, the accessory control circuit 201 returns to S606 to determine again whether an event has occurred, and if an event has occurred, the accessory control circuit 201 proceeds to S607.

[0244] In S607, the accessory control circuit 201 determines whether the event that occurred in S606 is an event that requires SPI communication with the camera 100. If the event requires SPI communication, the accessory control circuit 201 proceeds to S608, and if not, proceeds to S609.

[0245] In S609, the accessory control circuit 201 determines whether the event that occurred in S606 is an event that requires I2C communication with the camera 100. If the event requires I2C communication, the accessory control circuit 201 proceeds to S610, and if not, proceeds to S611.

[0246] In S611, the accessory control circuit 201 determines whether the event that occurred in S606 is an event that requires control using a function signal. If the event requires control using a function signal, the accessory control circuit 201 proceeds to S612, and if not, proceeds to S613.

[0247] In S613, the accessory control circuit 201 determines whether the event that occurred in S606 is an event that requires notification to the camera 100 by a communication request signal / WAKE. If the event requires notification to the camera 100 by a communication request signal / WAKE, the accessory control circuit 201 proceeds to S614, and if not, proceeds to S615.

[0248] In S608, the accessory control circuit 201 performs SPI communication with the camera 100. If the communication request signal / WAKE is at a low level during SPI communication, the communication request signal / WAKE is controlled to a high level after SPI communication. Examples of SPI communication performed here include, for example, if the accessory 200 is a microphone device, communication from the camera 100 instructing the camera 100 to turn on the microphone, communication instructing the camera 100 to turn off the microphone, and communication instructing the camera 100 to switch the microphone's sound collection directionality. There is also communication instructing the camera 100 to switch the microphone's equalizer function. Furthermore, if the accessory 200 is a flash device, there is communication to read setting information for the flash device, communication to notify the flash device of the setting information, and so on. When the predetermined SPI communication in S608 is completed, the accessory control circuit 201 returns to S606 and again determines whether an event has occurred.

[0249] In S610, the accessory control circuit 201 performs I2C communication with the camera 100. If the communication request signal / WAKE is at Lo level when the I2C communication is being performed, the communication request signal / WAKE is controlled to Hi level after the I2C communication. The I2C communication performed here includes, for example, communication for reading out the communication request cause (number) for the communication request signal / WAKE notified to the camera 100 by the accessory control circuit 201. When the I2C communication in S610 is completed, the accessory control circuit 201 returns to S606 and again determines whether an event has occurred.

[0250] In S612, the accessory control circuit 201 controls the camera 100 using the function signals. For example, if the accessory 200 is a microphone device, the control performed here includes control of reception of the audio data clock signal BCLK of FNC1 and the audio data channel signal LRCLK of FNC2 output from the camera 100. It also controls output of the audio data signal SDATA of FNC3 synchronized with these signals. If the accessory 200 is a strobe device, it also controls reception of the strobe light emission synchronization signal XOUT of FNC4 and control of strobe light emission in response to this. When the control using the function signals in S612 is completed, the accessory control circuit 201 returns to S606 and again determines whether an event has occurred.

[0251] In S614, the accessory control circuit 201 stores a communication request cause number for the camera 100 corresponding to the event that occurred in S606 in a volatile memory (not shown) of the accessory 200, and controls the communication request signal / WAKE to a low level. The communication request cause number is a unique number assigned to each cause content as shown in Fig. 8. When the control of the communication request signal / WAKE to a low level in S614 is completed, the accessory control circuit 201 returns to S606 and again determines whether an event has occurred.

[0252] In S615, the accessory control circuit 201 performs intra-accessory control in response to the event that occurred in S606. The intra-accessory control that is performed here includes control to detect the remaining battery charge when the accessory 200 is equipped with a battery 205, and control to detect operation of the operation switch 212. When the intra-accessory control in S615 is completed, the accessory control circuit 201 returns to S606 and again determines whether an event has occurred.

[0253] The above processing by the accessory control circuit 201 enables the accessory 200 to perform various functional operations after being attached to the camera 100.

[0254] Next, an example of the use of a communication request signal between the camera 100 and the accessory 200 in this embodiment will be described with reference to FIGS. 13 and 14. FIG. 13 shows the camera control circuit A101, the camera control circuit B102, the accessory control circuit 201, and the accessory power supply circuit 202 shown in FIG. 1. FIG. 13 also shows, among the contacts shown in FIG. 1, an accessory detection line 1000 including contacts TC06 / TA06 for the accessory attachment detection signal / ACC_DET, a power supply line 1001 including contacts TC05 / TA05 for the accessory power supply VACC, and a communication request line 1002 including contacts TC11 / TA11 for the communication request signal / WAKE. Furthermore, FIG. 13 shows a first communication line 1003 including contacts TC12 / TA12 and TC13 / TA13 for I2C communication and a second communication line 1004 including contacts TC07 / TA07 to TC10 / TA10 for SPI communication.

[0255] Fig. 14 shows the sequence of processing that is performed when accessory 200 is attached to camera 100. This sequence differs from the previously described sequence in Fig. 6 in the way that a communication request signal is used. Also, the explanation of the supply of accessory power shown in Fig. 6 will be simplified.

[0256] In S701, when the accessory 200 is attached to the camera 100, the accessory attachment detection signal / ACC_DET on the accessory detection line 1000 becomes low level. This causes the camera control circuit A101 to determine that the accessory 200 is attached to the camera 100.

[0257] The camera control circuit A101, which has determined that the accessory 200 has been attached, controls the accessory power supply VACC to be output to the power supply line 1001 in S702.

[0258] In S703, when the accessory 200 receives power from the accessory power supply VACC, the accessory control circuit 201 is started. The started accessory control circuit 201 initializes each block in the accessory 200.

[0259] Then, in S704, when the accessory control circuit 201 completes the above initialization, completes preparation for communication with the camera 100, and is ready for communication, it asserts (enables) the communication request signal / WAKE on the communication request line 1002 to a Lo level to notify the camera 100 that communication is permitted.

[0260] The timing at which the accessory 200 notifies the camera 100 of the permission for communication is not limited to after the accessory power supply VACC is supplied in S702. For example, if the accessory 200 has a built-in battery and is ready for communication when it is attached to the camera 100, the permission for communication may be notified when the accessory 200 is attached.

[0261] Next, in S705, the camera control circuit A101, which has received a notification of permission to communicate from the accessory 200, requests the accessory 200 to communicate accessory information by I2C communication via the first communication line 1003.

[0262] Next, in S706, the accessory control circuit 201, which has received the communication request for the accessory information, transmits the accessory information to the camera control circuit A101 via the first communication line 1003. However, transmission and reception of the accessory information via I2C communication does not have to be performed between the camera control circuit A101 and the accessory control circuit 201. For example, if the accessory control circuit 201 does not have a function for storing accessory information and the accessory information is stored in a separate storage device, transmission and reception of the accessory information may be performed between the camera control circuit A101 and the storage device.

[0263] Next, in S707, the camera control circuit A101 determines, based on the received accessory information, whether the attached accessory 200 can be controlled and the method for obtaining a cause of a communication request from the accessory 200. The camera control circuit A101 then performs various settings for the camera 100, and when this is complete, notifies the camera control circuit B102 of the accessory information.

[0264] Meanwhile, the accessory control circuit 201, which has transmitted the accessory information (or confirmed transmission of the accessory information from the storage device), negates (deactivates) the communication request signal / WAKE on the communication request line 1002 to Hi level in S708. This causes the camera 100 to transition to a state in which it waits for a communication request from the accessory 200.

[0265] The timing for negating the communication request signal / WAKE is not limited to after the accessory information is transmitted in S705. For example, if SPI communication is required between the camera 100 and the accessory 200 to transmit and receive the accessory information, the communication request signal / WAKE may be negated after the SPI communication is performed after the I2C communication.

[0266] Next, in S709, the accessory control circuit 201 asserts the communication request signal / WAKE on the communication request line 1002 to a low level to notify a communication request in order to perform an event that requires SPI communication with the camera 100 via the second communication line 1004.

[0267] Next, in S710, in response to the notified communication request, the camera control circuit B102 makes a request to the accessory 200 to acquire the cause of the communication request from the accessory 200. As described above, the cause of the communication request is included in the accessory information, and the camera control circuit B102 determines whether the request to acquire the cause of the communication request should be made via I2C communication or SPI communication, based on the accessory information. Here, a case where it is determined that the request should be made via SPI communication will be described.

[0268] In S711, in response to the request to acquire the communication request cause, the accessory control circuit 201 transmits the communication request cause to the camera 100 via SPI communication. Note that if the camera control circuit B102 determines in S710 to make a request to acquire the communication request cause via I2C communication, the accessory control circuit 201 transmits the communication request cause to the camera 100 via I2C communication.

[0269] 14 , the first (first) assertion of the communication request signal / WAKE on the communication request line 1002 after the accessory 200 is attached to the camera 100 and enters a communication-enabled state is used as a notification from the accessory 200 to the camera 100 of permission to communicate. Upon receiving this notification of permission to communicate, the camera 100 acquires accessory information from the accessory 200. Thereafter, upon occurrence of an event in the accessory 200 that requires communication with the camera 100, the second or subsequent assertion of the communication request signal / WAKE on the communication request line 1002 is used as a notification of a communication request from the accessory 200 to the camera 100. Upon receiving this notification of the communication request, the camera 100 acquires the cause of the communication request from the accessory 200.

[0270] As described above, in this embodiment, the accessory 200 notifies the camera 100 of a communication permission after being attached to the camera 100, thereby enabling transmission of accessory information to the camera 100. Moreover, the notification of communication permission from the accessory 200 to the camera 100 and the subsequent notification of a communication request can be performed using a communication request signal / WAKE connected to one (the same) communication request line 1002 provided between the camera 100 and the accessory 200. Therefore, it is possible to suppress an increase in the number of contacts between the camera 100 and the accessory 200, compared to when the notification of communication permission and the notification of a communication request are performed via separate contacts, while enabling the accessory 200 to notify the camera 100 of a communication permission or a communication request. [Example]

[0271] Next, a second embodiment of the present invention will be described with reference to Figures 15 and 16. In the second embodiment, a method of using a communication request signal when another accessory (hereinafter referred to as a second accessory) 300 is attached to an accessory (hereinafter referred to as a first accessory) 200 attached to a camera 100 will be described. This embodiment assumes that the first accessory 200 is an intermediate accessory, and the second accessory 300 is a flash device or the like connected to the camera 100 via the intermediate accessory.

[0272] The camera control circuit A101, camera control circuit B102, accessory control circuit 201, and accessory power supply circuit 202 shown in FIG. 15 are the same as those in FIG. 1. Also in FIG. 15, the accessory detection line 1000, power supply line 1001, communication request line 1002, first communication line 1003, and second communication line 1004 are the same as those in FIG. 13. Furthermore, FIG. 15 shows a communication request line 1005 and a third communication line (SPI / I2C) between the accessory connection unit 213 provided in the first accessory 200 and the accessory connection unit 302 provided in the second accessory 300. The accessory control circuit 201 in the first accessory 200 (hereinafter referred to as the first accessory control circuit) and the accessory control circuit 301 in the second accessory 300 (hereinafter referred to as the second accessory control circuit) can perform at least one of I2C communication and SPI communication via the third communication line.

[0273] In this embodiment, the first accessory 200 performs initial communication with the camera 100 via I2C communication, and then transmits communication content via SPI communication to the second accessory 300 via SPI communication. The first accessory 200 also transmits communication content via SPI communication from the second accessory 300 to the camera 100. The first accessory 200 also transmits a communication request signal from the second accessory 300 to the camera 100. The communication between the first accessory 200 and the second accessory 300 is controlled by a second accessory control circuit 301.

[0274] FIG. 16 shows the sequence of processing that is performed when the first and second accessories 200, 300 are attached to the camera 100.

[0275] In S801, when the first accessory 200 is attached to the camera 100, the accessory attachment detection signal / ACC_DET on the accessory detection line 1000 becomes Lo level. This causes the camera control circuit A101 to determine that the first accessory 200 (and further the second accessory 300) is attached to the camera 100.

[0276] The camera control circuit A101, which has determined that the first accessory 200 has been attached, performs control in S802 so that the accessory power supply VACC is output to the power supply line 1001. This starts up the first accessory control circuit 201. It is assumed that the main power supply of the second accessory 300 has already been turned on.

[0277] Next, in S803, when the first accessory control circuit 201 is ready to communicate with the camera 100 and is in a communication-enabled state, it asserts the communication request signal / WAKE on the communication request line 1002 to a low level to notify the camera 100 that communication is permitted.

[0278] The timing at which the first accessory 200 notifies the camera 100 of the permission for communication is not limited to after the accessory power supply VACC is supplied in S802. For example, if the first accessory 200 has a built-in battery and is ready for communication when the first accessory 200 is attached to the camera 100, the permission for communication may be notified when the first accessory 200 is attached.

[0279] Next, in S804, the camera control circuit A101, which has received a notification of permission to communicate from the first accessory 200, requests the first accessory 200 to communicate accessory information by I2C communication via the first communication line 1003.

[0280] Next, in S805, the first accessory control circuit 201, which has received the communication request for the accessory information, transmits the accessory information to the camera control circuit A101 via the first communication line 1003. However, transmission and reception of the accessory information via I2C communication does not have to be performed between the camera control circuit A101 and the accessory control circuit 201. For example, if the first accessory control circuit 201 does not have a function for storing accessory information and the accessory information is stored in a separate storage device, transmission and reception of the accessory information may be performed between the camera control circuit A101 and the storage device.

[0281] Next, in S806, the camera control circuit A101 determines, based on the received accessory information, whether the attached first accessory 200 can be controlled and the factor acquisition method to use when acquiring a communication request factor from the first accessory 200. The camera control circuit A101 then performs various settings for the camera 100, and when this is complete, notifies the camera control circuit B102 of the accessory information.

[0282] Next, in S807, the camera control circuit B102 performs initial communication (predetermined communication) for connecting to the second accessory 300 with the first accessory control circuit 201 by SPI communication via the second communication line 1004.

[0283] Then, in S808, the first accessory control circuit 201 sends a response to the initial communication in S807 to the camera control circuit B102 via SPI communication.

[0284] Next, in S809, the first accessory control circuit 201 negates the communication request signal / WAKE on the communication request line 1002 to Hi level. This causes the first accessory 200 to transition to a state in which it waits for a communication request from the second accessory 300.

[0285] Next, in S810, the second accessory control circuit 301 asserts the communication request signal / WAKE on the communication request line 1005 to a low level to notify a communication request in order to perform an event that requires SPI communication with the camera 100 through the first accessory 200.

[0286] Next, in S811, the first accessory control circuit 201 asserts the communication request signal / WAKE on the communication request line 1002 to Lo level in order to notify the camera 100 of a communication request from the second accessory 300.

[0287] Then, in S812, in response to the notified communication request, the camera control circuit B102 makes a request to the first accessory 200 to acquire the cause of the communication request from the second accessory 300. Based on the accessory information received in S805, the camera control circuit B102 determines whether the request to acquire the cause of the communication request should be made via I2C communication or SPI communication. Here, a case where it is determined that the request should be made via SPI communication will be described.

[0288] Next, in S813, the first accessory control circuit 201 transmits a request to acquire the cause of the communication request received from the camera 100 to the second accessory 300. At this time, the first accessory control circuit 201 converts the signal level (voltage level) of the request to acquire the cause of the communication request received from the camera 100 into a level suitable for communication with the second accessory 300.

[0289] Then, in S814, the second accessory control circuit 301 responds to the request to acquire the communication request cause and transmits the communication request cause to the first accessory 200 by SPI communication.

[0290] Next, in S815, the first accessory control circuit 201 transmits the communication request cause received from the second accessory 300 to the camera 100. At this time, the first accessory control circuit 201 converts the signal level of the communication request cause received from the second accessory 300 into a level suitable for communication with the camera 100.

[0291] In the present embodiment described above, the first (first) assertion of the communication request signal / WAKE on the communication request line 1002 after the first accessory 200 is attached to the camera 100 and is in a communication-enabled state is used as a notification from the first accessory 200 to the camera 100 of permission to communicate. Upon receiving this notification of permission to communicate, the camera 100 acquires accessory information from the first accessory 200. Thereafter, upon occurrence of an event in the second accessory 300 that requires communication with the camera 100, the second or subsequent assertion of the communication request signal / WAKE on the communication request line 1002 is used as a notification of a communication request from the second accessory 300 to the camera 100. Upon receiving this notification of the communication request, the camera 100 acquires the cause of the communication request from the second accessory 300 via the first accessory 200.

[0292] As described above, in this embodiment, the first accessory 200 notifies the camera 100 of a communication permission after being attached to the camera 100, thereby enabling transmission of accessory information to the camera 100. Moreover, the notification of communication permission from the first accessory 200 to the camera 100 and the notification of a communication request from the second accessory 300 to the camera 100 can be performed using a communication request signal / WAKE connected to one (the same) communication request line 1002 provided between the camera 100 and the first accessory 200. Therefore, it is possible to suppress an increase in the number of contacts between the camera 100 and the first accessory 200, compared to when the notification of communication permission and the notification of a communication request are performed via separate contacts, while enabling the first accessory 200 to notify the camera 100 of a communication permission or a communication request. [Example]

[0293] Next, a third embodiment of the present invention will be described with reference to Figures 17 and 18. In the third embodiment, a method of using a communication request signal when another accessory (hereinafter referred to as a third accessory) 400 is attached to an accessory (hereinafter referred to as a first accessory) 200 attached to a camera 100 will be described. This embodiment assumes that the third accessory 400 is a smartphone or a tablet terminal, and the first accessory 200 is a holder for holding the smartphone or tablet terminal. In this embodiment, the communication request signal / WAKE on the communication request line 1002 is used only to notify permission for communication.

[0294] The camera control circuit A101, camera control circuit B102, first accessory control circuit 201, and accessory power supply circuit 202 shown in Fig. 17 are the same as those in Fig. 15. Also in Fig. 17, the accessory detection line 1000, power supply line 1001, communication request line 1002, and first communication line 1003 are the same as those in Fig. 15. Furthermore, in Fig. 17, a fourth communication line 1006 includes contacts TC19 / TA19 and TC20 / TA20 shown in Fig. 1, and is used for USB communication. This fourth communication line 1006 is connected to an accessory control circuit 401 in the third accessory 400 (hereinafter referred to as the third accessory control circuit) via an accessory connection unit 215 provided in the first accessory 200 and an accessory connection unit 402 provided in the third accessory 400.

[0295] The third accessory control circuit 401 determines whether or not the camera 100 is in a state where communication is possible via the fourth communication line 1006 , and communicates with the camera 100 if it determines that communication is possible.

[0296] FIG. 18 shows the sequence of processing that is performed when the first and third accessories 200, 400 are attached to the camera 100.

[0297] S901 to S906 correspond to S801 to S806 in the second embodiment (FIG. 16).

[0298] In S907, the third accessory control circuit 401 acts as a host and communicates with the camera 100 via the fourth communication line 1006.

[0299] Next, in S908, the camera control circuit B102 responds to the communication received in S907 to the third accessory 400 via the fourth communication line 1006. From S904 to S908, the first accessory control circuit 201 maintains the assertion of the communication request signal / WAKE on the communication request line 1002.

[0300] In the present embodiment described above, the assertion of the communication request signal / WAKE on the communication request line 1002 only after the first accessory 200 is attached to the camera 100 and enters a communication-enabled state is used as a notification from the first accessory 200 to the camera 100 that communication is permitted. Upon receiving this notification of communication permission, the camera 100 acquires accessory information from the first accessory 200. Thereafter, the first accessory 200 permits communication between the camera 100 and the third accessory 400 by continuing to assert the communication request signal / WAKE.

[0301] As described above, in this embodiment, the notification of communication permission from the first accessory 200 to the camera 100 and the notification of communication permission between the third accessory 400 and the camera 100 can be performed using a communication request signal / WAKE connected to one (the same) communication request line 1002 provided between the camera 100 and the first accessory 200. Therefore, compared to when these notifications of communication permission are performed via separate contacts, it is possible to suppress an increase in the number of contacts between the camera 100 and the first accessory 200, while still enabling the first accessory 200 to notify the camera 100 of communication permission.

[0302] Although the above embodiment describes a case in which the accessory 200 is directly attached to the camera 100, other attachment configurations are also possible. For example, the camera 100 and the main accessory may communicate via a main accessory corresponding to the accessory 200 and an intermediate accessory such as an adapter device to which the camera 100 is attached. In this case, the intermediate accessory may perform communication control similar to at least a portion of the communication control performed by the accessory 200 and the camera 100 described in the above embodiment. Furthermore, the intermediate accessory may function as an information transmission path, such as outputting information corresponding to information input from the camera 100 to the main accessory and outputting information corresponding to information input from the main accessory to the camera 100. Thus, accessories as embodiments of the present invention include various accessories such as microphone devices, lighting devices, and adapter devices. Furthermore, adapter devices may also be included in electronic devices.

[0303] (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0304] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0305] 100 cameras 101 Camera control circuit A 102 Camera control circuit B 200 Accessories (1st Accessory) 201 Accessory control circuit 300 Second Accessory 400 Third Accessory

Claims

1. An accessory that is detachably attached to an electronic device, a communication request contact; A communication interface; an accessory processing means for communicating with the electronic device using the communication request contact and the communication contact; The accessory processing means When the accessory is attached to the electronic device and communication with the electronic device is possible, a communication request signal connected to the communication request contact is enabled for the first time to allow a request for accessory information for identifying the accessory from the electronic device; In response to the request, transmitting the accessory information to the electronic device via the communication contacts; notifying the electronic device of a communication request by re-enabling the communication request signal after transmitting the accessory information; An accessory that transmits a communication request cause via the communication contact to the electronic device that has responded to the communication request.

2. The accessory processing means receiving a request for the accessory information from the electronic device and transmitting the accessory information to the electronic device using a first communication method; 2. The accessory according to claim 1, wherein the communication request cause is transmitted to the electronic device using a second communication method different from the first communication method.

3. The accessory described in claim 2, characterized in that the accessory processing means cancels the validity of the communication request signal for permitting the request for the accessory information after the accessory information is transmitted using the first communication method and after a predetermined communication with the electronic device is performed using the second communication method.

4. 4. The accessory according to claim 2, wherein the first communication method is an I2C communication method, and the second communication method is an SPI communication method.

5. When another accessory is attached to the accessory, The accessory processing means notifying the electronic device of a communication request from the other accessory to the electronic device by enabling the communication request signal; The accessory according to claim 1 , wherein the accessory transmits a communication request cause from the other accessory to the electronic device that has responded to the communication request via the communication contact.

6. When another accessory is attached to the accessory, The accessory described in claim 1, characterized in that the accessory processing means maintains the validity of the communication request signal for permitting the request for the accessory information until communication between the electronic device and the other accessory that takes place after the transmission of the accessory information is completed.

7. Electronic devices and A system comprising the accessory according to any one of claims 1 to 6, which is detachably attached to the electronic device.

8. An electronic device to which an accessory is detachably attached, a communication request contact; A communication interface; a processing means for communicating with the accessory using the communication request contact and the communication contact; The processing means When the accessory is attached to the electronic device and communication with the accessory is possible, a communication request signal connected to the communication request contact is first enabled by the accessory, thereby requesting the accessory to transmit accessory information for identifying the accessory; receiving the accessory information transmitted from the accessory in response to the request via the communication contact; receiving notification of a communication request by the accessory re-enabling the communication request signal after receiving the accessory information; In response to the communication request, the electronic device receives a communication request factor from the accessory via the communication contact.

9. The processing means transmitting a request for the accessory information to the accessory and receiving the accessory information from the accessory in a first communication method; 9. The electronic device according to claim 8, wherein the communication request cause is received from the accessory using a second communication method different from the first communication method.

10. The accessory described in claim 9, characterized in that the processing means performs predetermined communication with the accessory using the second communication method before the validity of the communication request signal for permitting the request for the accessory information is released after the accessory information is transmitted using the first communication method.

11. 11. The electronic device according to claim 9, wherein the first communication method is an I2C communication method, and the second communication method is an SPI communication method.

12. When another accessory is attached to the accessory, The processing means receiving a notification of a communication request from the other accessory to the electronic device by the accessory enabling the communication request signal; 12. The electronic device according to claim 8, wherein in response to the communication request, a communication request cause is received from the other accessory via the communication contact.

13. When another accessory is attached to the accessory, The processing means 9. The electronic device according to claim 8, wherein the accessory information is received and communication between the electronic device and the other accessory is performed while the communication request signal for permitting the request for the accessory information is maintained valid.

14. An electronic device according to any one of claims 8 to 13; and an accessory that is detachably attached to the electronic device.

15. A method for controlling an accessory that is detachably attached to an electronic device and has a communication request contact and a communication contact, comprising: When the accessory is attached to the electronic device and communication with the electronic device is possible, a step of first enabling a communication request signal connected to the communication request contact to allow a request for accessory information for identifying the accessory from the electronic device; In response to the request, transmitting the accessory information to the electronic device via the communication contacts; after transmitting the accessory information, notifying the electronic device of a communication request by re-enabling the communication request signal; a step of transmitting a communication request cause via the communication contact to the electronic device that has responded to the communication request.

16. A method for controlling an electronic device to which an accessory is detachably attached and which has a communication request contact and a communication contact, comprising: a step of requesting the accessory to transmit accessory information for identifying the accessory by first enabling a communication request signal connected to the communication request contact by the accessory when the accessory is attached to the electronic device and communication with the accessory is possible; receiving, via the communication contact, the accessory information transmitted from the accessory in response to the request; receiving notification of a communication request by the accessory re-enabling the communication request signal after receiving the accessory information; a step of receiving a communication request cause from the accessory via the communication contact in response to the communication request.

17. 16. A program for causing a computer of an accessory that is detachably attached to an electronic device and has a communication request contact and a communication contact to execute processing according to the control method of claim 15.

18. 17. A program for causing a computer of an electronic device to which an accessory is detachably attached and which has a communication request contact and a communication contact to execute processing according to the control method of claim 16.

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