Digital input device and digital input system

Abstract

To input digital information with low power consumption without increasing a circuit scale.SOLUTION: A digital input device 10 comprises: a wireless chip 11 that is wirelessly communicable with an interrogator 20 via backscatter communication and generates a power supply voltage from radio waves transmitted from the interrogator 20, the wireless chip 11 including an SPI power supply voltage terminal, a ground terminal, and an MISO terminal; and a switch unit 12 that controls a contact between the power supply voltage terminal and the ground terminal with respect to the MISO terminal. By switching on and off the switch unit 12, digital information of a prescribed bit of 0 or 1 is input into the wireless chip 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The disclosed technology relates to a digital input device and a digital input system.

Background Art

[0002] Conventionally, techniques for performing serial communication between a master and a slave using a serial communication interface such as SPI (Serial Peripheral Interface) or I2C (Inter-Integrated Circuit) are known (see, for example, Patent Document 1).

[0003] For example, in a digital input device using an SPI slave, digital information in 8-bit units can be transmitted by reacting to commands and specified addresses from an SPI master at an appropriate timing. Usually, a plurality of shift registers in 8-bit units are used, and the SPI master sequentially reads the shift registers in 8-bit units, so that digital information of more than 8 bits can also be transmitted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, obtaining contact information, which is digital information, remotely is in demand in many applications such as detecting button presses, checking switch states, checking door openings and closings, and acquiring trigger signals. There are also products equipped with such GPI (General Purpose Input) functions among commercially available wireless transceiver chips. However, in this type of product, it is necessary to prepare GPI ports and pads according to the number of input contacts, increasing the circuit scale.

[0006] In addition, a chip called a GPIO expander that connects multiple GPI ports to serial communication interfaces such as SPI and I2C is also commercially available. However, since this GPIO expander itself has an SPI slave function and other additional functions, its power consumption is high.

[0007] The disclosed technology has been made in view of the above points, and an object thereof is to provide a digital input device and a digital input system that can input digital information with low power consumption without increasing the circuit scale.

Means for Solving the Problems

[0008] The digital input device according to the disclosed technology is a digital input device capable of inputting digital information via a serial communication interface, and is a wireless chip capable of wireless communication with an interrogator by backscatter communication and generating a power supply voltage from radio waves transmitted from the interrogator. The wireless chip includes a power supply voltage terminal, a ground terminal, and an MISO terminal of the serial communication interface, and a switch unit that controls the contact between the power supply voltage terminal and the ground terminal with respect to the MISO terminal. By switching the on and off of the switch unit, the digital information of 0 or 1 of a predetermined number of bits is input to the wireless chip.

[0009] Furthermore, it further includes one or more shift registers in units of a predetermined number of bits. The switch unit has a number of contact points equal to or less than the product of the number of bits of the predetermined number of bits and the number of shift registers connected to the data port of the shift register. The wireless chip adjusts the MSB or LSB of the data according to the timing of reading the data from the switch unit, and cyclically shifts the shift register at the rising or falling timing of the clock of the wireless chip, so that digital information may be input in multiples of the number of bits equal to or more than the number of contact points.

[0010] Also, the serial communication interface may be SPI.

[0011] Also, the predetermined bit may be 8 bits.

[0012] A digital input system according to the disclosed technology is a digital input system including an interrogator and a digital input device capable of inputting digital information via a serial communication interface, wherein the digital input device is capable of wireless communication with the interrogator by backscatter communication, and is a wireless chip that generates a power supply voltage from radio waves transmitted from the interrogator, the wireless chip including a power supply voltage terminal, a ground terminal, and an MISO terminal of the serial communication interface, and a switch unit that controls the contact between the power supply voltage terminal and the ground terminal with respect to the MISO terminal, and by switching on and off the switch unit, digital information of 0 or 1 of a predetermined bit is input to the wireless chip.

Advantages of the Invention

[0013] According to the disclosed technology, digital information can be input with low power consumption without increasing the circuit scale.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 7C

[0015] Hereinafter, an example of an embodiment of the disclosed technology will be described with reference to the drawings. In the drawings, the same or equivalent components and parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0016] [First Embodiment] FIG. 1 is a block diagram showing an example of the configuration of a digital input system 1 according to the first embodiment. The digital input system 1 includes an interrogator 20 and a digital input device 10. The digital input system 1 constitutes a wireless tag system in which the interrogator 20 and the digital input device 10 can communicate with each other by backscatter communication.

[0017] Backscatter communication is a communication method using radio wave reflection. The digital input device 10 that has received the radio wave transmitted by the interrogator 20 can transmit information from the digital input device 10 to the interrogator 20 by carrying digital information when reflecting the radio wave. A typical application form of backscatter communication is a passive RFID (Radio Frequency Identification) system. In passive RFID, digital information can be obtained from a digital input device 10 not equipped with a power source at a distance of about 10 m from the interrogator 20 by obtaining power for driving the digital input device 10 (wireless tag) from the radio wave transmitted from the interrogator 20.

[0018] As shown in FIG. 1, the digital input device 10 according to the present embodiment has a wireless chip 11 and a switch unit 12. The wireless chip 11 is an RFIC (radio frequency integrated circuit) capable of wireless communication with the interrogator 20 by backscatter communication. The wireless chip 11 generates a power supply voltage VDD for driving the wireless chip 11 and the switch unit 12 from the radio waves sent from the interrogator 20. The power supply voltage VDD is supplied to the switch unit 12 via the power supply line L p .

[0019] The switch unit 12 is connected to the wireless chip 11 via the signal line L S and the power supply line L P . The switch unit 12 is a switch that switches between on and off according to the state of the object. The "object" here is assumed to be an object such as a button, a door, a lid, etc. that can be switched between on and off, open and closed, but it only needs to have two switchable states and is not limited to these. The switch unit 12 is driven by the power supply voltage VDD supplied via the power supply line L P . The switch unit 12 transmits digital information (also referred to as "contact information") corresponding to the state of the object to the wireless chip 11 via the signal line L S . A serial communication interface such as SPI or I2C is used for the communication interface between the switch unit 12 and the wireless chip 11. The wireless chip 11 acquires digital information from the switch unit 12 based on a command from the interrogator 20 and transmits this to the interrogator 20.

[0020] FIG. 2 is a block diagram showing an example of the specific configuration of the digital input device 10 according to the first embodiment. In the example of FIG. 2, the case where SPI is applied as an example of the serial communication interface is shown.

[0021] As shown in FIG. 2, the wireless chip 11 can perform wireless communication with the interrogator 20 by backscatter communication and generates the power supply voltage VDD from the radio waves transmitted from the interrogator 20. That is, the wireless chip 11 has a function as an SPI master. The wireless chip 11 includes terminals of the SPI master, that is, a VDD terminal which is a power supply voltage terminal, an nCS (Chip Select) terminal, an SCK (Serial Clock) terminal, a MOSI (Master Out Slave In) terminal, a MISO (Master In Slave Out) terminal, and a GND terminal which is a ground terminal.

[0022] The VDD terminal is a terminal for supplying the generated power supply voltage VDD to the switch unit 12. The nCS terminal is a terminal for outputting a CS signal for selecting the switch unit 12 with which the wireless chip 11 communicates. The SCK terminal is a terminal for outputting an SCK signal which is a clock signal in SPI communication. The SCK signal is generated by the wireless chip 11 and transmitted from the wireless chip 11 to the switch unit 12. In synchronization with the rising or falling edge of this SCK signal, the data of the MISO signal is transferred one bit at a time. Note that the frequency of the SCK signal is, for example, several MHz to several tens of MHz.

[0023] The MOSI terminal is a terminal for outputting a MOSI signal. The MOSI signal is a data signal transmitted from the wireless chip 11 to the switch unit 12. The MISO terminal is a terminal for outputting a MISO signal. The MISO signal is a data signal transmitted from the switch unit 12 to the wireless chip 11. The GND terminal is a terminal used for grounding.

[0024] In the digital input device 10 according to this embodiment, by providing the switch unit 12 with a simple circuit configuration to the wireless chip 11 having an SPI master function without using an SPI slave, digital information can be acquired with low power consumption and low cost.

[0025] The switch unit 12 controls the connection between the VDD terminal and the GND terminal with respect to the MISO terminal. The switch unit 12 includes a SPST (Single-Pole Single-Throw) switch 121 and a pull-down resistor 122. One end of the SPST switch 121 is connected to the VDD terminal, and the other end is connected to the pull-down resistor 122. One end of the pull-down resistor 122 is connected to the GND terminal, and the other end is connected to the SPST switch 121. When using a SPDT (Single-Pole Double-Throw) switch, the pull-down resistor 122 is not required. Also, when it is possible to output 0 / 1 digital information, it may be directly input to the MISO terminal.

[0026] By switching the on and off states of the SPST switch 121 according to the state of the object, digital information of 0 or 1 of a predetermined number of bits (for example, 8 bits) is input to the wireless chip 11. That is, when the digital information is 1 bit, the digital information is directly input to the MISO terminal of the wireless chip 11 by switching the on and off states of the SPST switch 121.

[0027] FIG. 3 is a diagram showing an example of waveforms of the nCS signal, SCK signal, and MISO signal according to the first embodiment.

[0028] As shown in FIG. 3, for example, when the nCS signal is at a low level, the SCK signal is output, and in synchronization with the rising edge of this SCK signal, the data of the MISO signal is transferred one bit at a time. That is, the on / off state of the SPST switch 121 is directly reflected in the MISO signal. When the predetermined number of bits is 8, from the perspective of the wireless chip 11, when the SPST switch 121 is on, it can be read as 0xFF, and when the SPST switch 121 is off, it can be read as 0x00 (except when the state of the switch transitions).

[0029] According to this embodiment, the digital input device can be realized simply by adding a switch section with a simple circuit configuration to a wireless chip having an SPI master function. That is, since no additional components are required, digital information can be acquired remotely with low power consumption and low cost.

[0030] [Second Embodiment] In the above first embodiment, the form of the digital input device when the digital information is 1 bit was described. In the second embodiment, the form of the digital input device when the digital information is multiple bits will be described.

[0031] FIG. 4 is a block diagram showing an example of the configuration of a digital input system 1A according to the second embodiment. The digital input system 1A includes an interrogator 20 and a digital input device 10A. The digital input system 1A constitutes a wireless tag system in which the interrogator 20 and the digital input device 10A can communicate with each other by backscatter communication.

[0032] Regarding the digital input system 1A according to the second embodiment, the same reference numerals are given to the same components as those of the digital input system 1 described in the first embodiment above, and the repeated description thereof is omitted.

[0033] As shown in FIG. 4, the digital input device 10A according to this embodiment includes a wireless chip 11, a switch section 12, and a shift register 13. The wireless chip 11 and the shift register 13 are connected via serial communication, and the shift register 13 and the switch section 12 are connected via parallel communication. That is, when the digital information (contact information) is multiple bits, the digital information from the switch section 12 is converted from parallel to serial by the shift register 13 and transmitted to the wireless chip 11.

[0034] FIG. 5 is a block diagram showing an example of the specific configuration of the digital input device 10A according to the second embodiment. In the example of FIG. 5, the case where SPI is applied as an example of the serial communication interface is shown.

[0035] The shift register 13 is one or more shift registers with a predetermined number of bits (e.g., 8 bits) as a unit. The shift register 13 may be configured, for example, as an 8-bit (one unit) shift register, or may be configured by cascading a plurality of shift registers with 8 bits as one unit. The shift register 13 has one or more data ports, and one unit of shift register is connected to one data port.

[0036] The switch unit 12 has the number of contacts equal to or less than the number obtained by multiplying the number of shift registers connected to the data port of the shift register 13, that is, the number of units of the shift register, by the number of bits of the predetermined number of bits (e.g., "8" if 8 bits).

[0037] The wireless chip 11 has a function of adjusting the MSB (Most Significant Bit) or LSB (Least Significant Bit) of the data according to the timing of reading the data from the switch unit 12.

[0038] The wireless chip 11 inputs digital information in multiples of the number of bits of a predetermined number of bits (e.g., "8" if 8 bits) equal to or more than the number of contacts of the switch unit 12 by cyclically shifting the shift register 13 at the rising or falling timing of the clock of the wireless chip 11.

[0039] Specifically, the shift register 13 has an nSH / LD (Shift or Load) terminal, a CLK (Clock) terminal, a Sout terminal, and a Sin terminal. The nSH / LD terminal is connected to the nCS terminal of the wireless chip 11, and the CLK terminal is connected to the SCK terminal of the wireless chip 11. The Sout terminal is connected to the MISO terminal of the wireless chip 11, and the Sin terminal is connected to the MISO terminal of the wireless chip 11.

[0040] Further, the shift register 13 has eight input terminals of Pin_0 to Pin_7, and each of these eight input terminals is connected to the contact of the switch section 12.

[0041] That is, using the nCS signal of the wireless chip 11, it is switched whether to latch or shift the contact information from the switch section 12 in the shift register 13. Then, using the SCK signal of the wireless chip 11, the shift register 13 is shifted. Then, the values of Pin_7 to Pin_0 of the shift register 13 are output to the wireless chip 11 as the MISO signal.

[0042] FIG. 6 is a diagram showing an example of waveforms of the nCS signal, the SCK signal, and the MISO signal according to the second embodiment.

[0043] As shown in FIG. 6, for example, when the nCS signal is at a low level, the SCK signal is output, and in synchronization with the rising edge of this SCK signal, the data b7 to b0 of the MISO signal are transferred. The values of Pin_7 to Pin_0 of the shift register 13 (see FIG. 5) correspond to the data b7 to b0 of the MISO signal and are output.

[0044] FIG. 7A is a diagram showing an example of waveforms of the MISO signal, the MOSI signal, the SCK signal, and the CS signal during normal SPI reading. FIG. 7B is a diagram showing an example of waveforms of the MISO signal, the MOSI signal, the SCK signal, and the CS signal of the 1-bit switch according to the first embodiment. FIG. 7C is a diagram showing an example of waveforms of the MISO signal, the MOSI signal, the SCK signal, and the CS signal of the 8-bit switch according to the second embodiment.

[0045] Thus, according to this embodiment, it is possible to input digital information of multiple bits only by adding a general-purpose shift register.

[0046] Also, compared with a GPIO expander, it has a low cost and low power consumption, and further, since register setting of the GPIO expander is not required, it can be realized with a simple configuration.

[0047] Also, by cascading shift registers, the input of digital information can be increased in multiples of the number of bits of the shift register.

[0048] Regarding the above embodiments, the following additional remarks are disclosed.

[0049] (Supplementary Note 1) A digital input device capable of inputting digital information via a serial communication interface, a wireless chip capable of wireless communication with an interrogator by backscatter communication and generating a power supply voltage from radio waves transmitted from the interrogator, the wireless chip including a power supply voltage terminal, a ground terminal, and an MISO terminal of the serial communication interface, a switch unit that controls the connection between the power supply voltage terminal and the ground terminal with respect to the MISO terminal, comprising By switching on and off the switch unit, digital information of 0 or 1 of a predetermined number of bits is input to the wireless chip. Digital input device. (Supplementary Note 2) further comprising one or more shift registers in units of a predetermined number of bits, the switch unit has a number of connection points equal to or less than the number obtained by multiplying the number of bits of the predetermined number of bits by the number of shift registers connected to the data port of the shift register, the wireless chip adjusts the MSB or LSB of the data according to the timing of reading the data from the switch unit, By cyclically shifting the shift register at the rising or falling timing of the clock of the wireless chip, digital information is input in multiples of the number of bits of the predetermined number of bits equal to or more than the number of connection points. The digital input device according to Supplementary Note 1. (Supplementary Note 3) The serial communication interface is SPI. The digital input device according to Supplementary Note 1 or Supplementary Note 2. (Supplementary Note 4) The predetermined bit is 8 bits. The digital input device according to any one of Appendices 1 to 3. (Appendix 5) An interrogator, A digital input device capable of inputting digital information via a serial communication interface, A digital input system including The digital input device A wireless chip capable of wireless communication with the interrogator by backscatter communication and generating a power supply voltage from radio waves transmitted from the interrogator, the wireless chip including a power supply voltage terminal, a ground terminal, and an MISO terminal of the serial communication interface, A switch unit that controls the contact between the power supply voltage terminal and the ground terminal with respect to the MISO terminal, Comprising By switching the on and off of the switch unit, the digital information of 0 or 1 of a predetermined bit is input to the wireless chip. Digital input system.

Description of Signs

[0050] 1, 1A Digital input system 10, 10A Digital input device 11 Wireless chip 12 Switch unit 13 Shift register 20 Interrogator 121 SPST switch 122 Pull-down resistor

Claims

1. A digital input device capable of inputting digital information via a serial communication interface, a wireless chip capable of wireless communication with an interrogator by backscatter communication and generating a power supply voltage from radio waves transmitted from the interrogator, the wireless chip including a power supply voltage terminal, a ground terminal, and an MISO terminal of the serial communication interface, a switch unit that performs contact control between the power supply voltage terminal and the ground terminal with respect to the MISO terminal, comprising: by switching on and off the switch unit, inputting the digital information of 0 or 1 of a predetermined number of bits to the wireless chip, a digital input device.

2. further comprising one or more shift registers in units of a predetermined number of bits, the switch unit having a number of contact points equal to or less than the product of the number of bits of the predetermined number of bits and the number of shift registers connected to the data port of the shift register, the wireless chip adjusting the MSB or LSB of the data in accordance with the timing of reading data from the switch unit, inputting digital information in multiples of the number of bits of the predetermined number of bits equal to or more than the number of contact points by cyclically shifting the shift register at the rising or falling timing of the clock of the wireless chip, The digital input device according to claim 1.

3. The serial communication interface is SPI, The digital input device according to claim 1 or claim 2.

4. The predetermined number of bits is 8 bits, The digital input device according to claim 1 or claim 2.

5. an interrogator, a digital input device capable of inputting digital information via a serial communication interface, a digital input system including: the digital input device is a wireless chip capable of wireless communication with the interrogator by backscatter communication and generating a power supply voltage from radio waves transmitted from the interrogator, the wireless chip including a power supply voltage terminal, a ground terminal, and an MISO terminal of the serial communication interface, a switch unit that performs contact control between the power supply voltage terminal and the ground terminal with respect to the MISO terminal, comprising: by switching on and off the switch unit, inputting the digital information of 0 or 1 of a predetermined number of bits to the wireless chip, a digital input system.

Images