Communication systems and communication methods

Abstract

A communication system is obtained that can switch the clock used so that when the slave unit receives commands from the master unit, it can receive data in synchronization with the master clock, and when the slave unit sends data to the master unit, it can send data in synchronization with the slave clock. [Solution] The slave unit SN1 receives a command from the master unit 1 that includes the slave ID, master clock, and request data. After the slave control unit 5 writes the request data to the memory 6 using the master clock, the slave clock generator 7 turns from off to on. The transmission unit 8 reads the request data from the memory 6 using the slave clock generated by the slave clock generator 7. After reading the request data, the transmission unit 8 generates read data and sends the read data to the master unit 1. After the transmission unit 8 sends the read data, the slave clock generator 7 turns from on to off.

Description

Technical Field

[0001] The present disclosure relates to a communication system and a communication method.

Background Art

[0002] In a conventional communication system, data is transmitted and received between one master unit and a slave unit group composed of a plurality of slave units. Furthermore, communication can be performed with high noise resistance using differential signals.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a communication system, there is a demand to simplify wiring by reducing clock lines. When the clock lines are reduced, data can be received using the master clock when data is sent from the master unit to each slave unit. However, when data is transmitted from the slave unit to the master unit, the slave unit that transmits data to the master unit occupies the data line, so the master unit cannot obtain a clock. Therefore, there has been a problem that transmission from the slave unit to the master unit cannot be performed.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to operate by switching the clock used so that the slave unit can receive a command in synchronization with the master clock when receiving a command from the master unit, and can transmit data in synchronization with the slave clock when transmitting data to the master unit.

Means for Solving the Problems

[0006] The communication system relating to this disclosure includes a master unit that transmits a command including a slave ID, a master clock, and instruction data, and temporarily stops transmitting the command if the instruction data is request data; a slave clock generator that outputs a slave clock; and a memory. The system also includes a slave unit that receives the command transmitted from the master unit, and if the slave ID matches its own slave ID and the instruction data is request data, it writes the request data to the memory using the master clock, reads the request data written to the memory using the slave clock output from the slave clock generator, and transmits generated data generated based on the request data to the master unit.

[0007] Furthermore, the communication method relating to this disclosure includes the steps of: determining whether the slave ID included in a command transmitted by the master unit to the slave unit, which includes a slave ID, a master clock, and instruction data, matches its own slave ID; determining whether the instruction data is request data if the slave ID matches its own slave ID; writing the request data to memory using the master clock included in the command if the instruction data is request data; turning on the slave clock generator after writing the request data to memory to generate the slave clock; reading the request data from memory using the slave clock after turning on the slave clock generator and transmitting generated data generated based on the request data to the master unit; and stopping the slave clock after transmitting the generated data to the master unit by turning on the slave clock generator. [Effects of the Invention]

[0008] The communication system disclosed herein can also transmit data from the slave unit to the master unit by switching the clock used so that when the slave unit receives a command from the master unit, it can receive data in synchronization with the master clock, and when the slave unit transmits data to the master unit, it can transmit data in synchronization with the slave clock. [Brief explanation of the drawing]

[0009] [Figure 1] A block diagram showing the configuration of the communication system in Embodiment 1 of this disclosure. [Figure 2] Transaction timing chart of a communication system in Embodiment 1 of this disclosure. [Figure 3] A flowchart showing the processing flow of the communication system in Embodiment 1 of this disclosure. [Figure 4] Transaction timing chart of a communication system in Embodiment 2 of this disclosure. [Modes for carrying out the invention]

[0010] Embodiment 1. The communication system in Embodiment 1 will be described in detail with reference to the drawings. Figure 1 shows the configuration of a communication system. As shown in Figure 1, the communication system 100 consists of a differential transmission bus 9, a master unit 1, and a plurality of slave units 200. The master unit 1 includes a master control unit 3, a master transceiver MT, and a master receiver MR.

[0011] Each slave unit 200 is comprised of a clock data recovery unit (hereinafter referred to as the CDR unit) 4, a slave control unit 5, a memory 6, a slave clock generation unit 7, a transmission unit 8, a slave transceiver ST, and a slave receiver SR.

[0012] The differential transmission bus 9 is connected to the differential signal lines from the master transceiver MT and the master receiver MR. Furthermore, the differential transmission bus 9 is also connected to the differential signal lines from the slave transceiver ST and the slave receiver SR. In other words, the master unit 1 and the slave unit 200 are connected by the differential transmission bus 9.

[0013] The slave unit 200 is a collective term for the n slave units included in the slave unit 200. When it is necessary to distinguish each slave unit, they will be referred to as slave unit SN1, slave unit SN2, ..., slave unit SNn in the following explanation.

[0014] The master unit 1 transmits a command containing the clock information generated by the master control unit 3 (hereinafter referred to as the master clock), the ID of the target slave unit, and instruction data to each of the n slave units of the slave unit 200 (i.e., each of the n slave units shown in Figure 1 as slave unit SN1, slave unit SN2...slave unit SNn, etc.) via the master transceiver MT.

[0015] In the following explanation, the slave IDs of each slave unit 200 will be described as follows: the slave ID of slave unit SN1 is SN1, the slave ID of slave unit SN2 is SN2, ... the slave ID of slave unit SNn is SNN.

[0016] Furthermore, when referring to the CDR units 41, 42, ..., 4n collectively, they shall be called CDR unit 4. Similarly, when referring to the slave control units 51, 52, ..., 5n collectively, they shall be called slave control unit 5. Furthermore, when referring to the memory units 61, 62, ..., 6n collectively, they shall be called memory 6. Furthermore, when referring to the slave clock generation units 71, 72, ..., 7n collectively, they shall be called slave clock generation unit 7. When referring to the transmission units 81, 82, ..., 8n collectively, they shall be called transmission unit 8.

[0017] In Embodiment 1, as shown in FIG. 1, the commands output from the master unit 1 are transmitted to each of the slave units 200 through the differential transmission bus 9. The instruction data included in the commands transmitted from the master unit 1 includes either one of two types. One of the two types of instruction data is instruction data (hereinafter referred to as request data) that instructs the slave unit 200 to send data to the master unit 1. And the other of the two types of instruction data is instruction data (hereinafter referred to as control data) for giving a control instruction from the master unit 1 to each slave unit of the slave unit 200.

[0018] The slave unit SN1 receives the command transmitted from the master unit 1 by the slave receiver SR1. The CDR unit 41 separates the received command into a clock and instruction data, and reproduces the instruction data using the master clock. When the slave ID included in the instruction data is SN1 and matches the own ID of the slave unit SN1, the slave control unit 51 included in the slave unit SN1 operates using the master clock separated by the CDR unit 41 included in the slave unit SN1.

[0019] Also, based on the slave ID included in the command output from the master unit 1, it is possible to select the slave unit to be operated among the slave units included in the slave unit 200. As a result, since all the slave units to be operated operate using the master clock, it is also possible to achieve time synchronization among the respective slave units included in the slave unit 200.

[0020] Hereinafter, the operation of the slave unit SN1 will be described as a representative example. The slave units SN2, SN3, and SNn operate in the same manner although the transmission timing to the master unit 1 is different from that of the slave unit SN1, and thus the detailed description thereof will be omitted.

[0021] When the instruction data output from the master unit 1 is request data, the slave control unit 51 controls to write the request data into the memory 61 using the master clock. After the request data is written into the memory 61, the slave control unit 51 outputs a flag signal indicating write completion to the slave clock generation unit 71. Upon receiving the flag indicating write completion, the slave clock generation unit 71 is activated (activation is also referred to as being turned on), and the slave clock generation unit 71 outputs a slave clock.

[0022] The slave clock generated by the slave clock generation unit 71 is output to the memory 61 and the transmission unit 81, and the memory 61 and the transmission unit 81 operate using the slave clock respectively. The slave clock generation unit 71 may be a clock generation unit provided in each slave unit included in the slave unit 200, or may be a clock generation unit provided outside the slave unit 200 and configured to supply a slave clock to each slave unit included in the slave unit 200.

[0023] The transmission unit 81 is responsible for generating and transmitting control of data (hereinafter referred to as generated data) transmitted from the slave unit SN1 to the master unit 1. The transmission unit 81 reads the request data from the memory 61 operating with the slave clock in synchronization with the slave clock, and generates generated data according to the request of the request data. After generating the generated data, the transmission unit 81 transmits the generated data and the slave clock from the slave transceiver ST1 to the master unit 1 in synchronization with the slave clock.

[0024] After transmitting the generated data, the transmission unit 81 outputs a flag signal indicating transmission completion to the slave clock generation unit 71. When the slave clock generation unit 71 receives the flag indicating transmission completion of the generated data from the transmission unit 81, it is deactivated (deactivation is also referred to as being turned off), and the slave clock generation unit 71 stops outputting the slave clock.

[0025] The master unit 1 receives generated data and a slave clock from the slave unit SN1 via the master receiver MR. The received generated data is separated into the slave clock and the generated data by the CDR unit (not shown) of the master control unit 3, and the generated data is processed using the slave clock.

[0026] Next, the operation of the notification system 100 in the embodiment 1 configured as described above will be explained using Figure 2. Figure 2 is a diagram showing the transaction timing chart of the communication system 100.

[0027] In Figure 2, (a) shows the transmission interval and timing for each command and data, (b) shows the operating mode of the master unit 1, (c) shows the operating mode of the slave unit SN1, (d) shows the timing of the master clock, and (e) shows the timing of the slave clock.

[0028] As can be seen in Figure 2, in the state before communication between the master unit 1 and the slave unit SN1 is initiated (hereinafter referred to as the "initial state"), the operating mode of the master unit 1 (indicated as "Master" in Figure 2) is set to TX mode (indicated as "TX mode" in Figure 2), and the operating mode of the slave unit 200 (indicated as "Slave" in Figure 2) is set to RX mode (indicated as "RX mode" in Figure 2).

[0029] When communication is initiated between the master unit 1 and the slave unit SN1, the master unit 1 first sends a command to the slave unit SN1 via the master transceiver MT. Time t10 is defined as the time when the master unit 1 has finished sending the command to the slave unit SN1.

[0030] This section describes an example where the master unit 1 begins sending a command containing request data (labeled "Request command" in Figure 2) to the slave unit SN1. After sending a command containing the request data, the master unit 1 temporarily stops sending commands to the slave unit 200 until the timing described later. Commands received by the slave unit SN1 from the master unit 1 via the slave receiver SR1 are separated into the master clock and instruction data by the CDR unit 41, and the instruction data is reproduced using the master clock.

[0031] Since the instruction data received from the master unit 1 is the request data, the slave control unit 51 writes the request data to the memory 61 using the master clock, and then the slave control unit 51 outputs a flag signal indicating completion of writing (indicated as "Slave clock" in Figure 2; in particular, the flag signal for the part where the Slave clock transitions from off to on at time t20, which will be described later) to the slave clock generator 71.

[0032] When the slave clock generator 71 receives the flag indicating that writing is complete, the slave clock generator 71 switches from off to on and outputs the slave clock. When the slave clock generator 71 switches from off to on, the slave unit SN1 switches from RX mode to TX mode. This time is denoted as time t20.

[0033] After the slave unit SN1 switches to TX mode, each part of the slave unit SN1 operates using the slave clock. The transmitter unit 81 reads the request data from the memory 61, which operates on the slave clock, in synchronization with the slave clock, and generates generated data using a generated data generation unit (not shown), which also operates on the slave clock, according to the request data. After generating the generated data, the transmitter unit 81 transmits the generated data and the slave clock from the slave transceiver ST1 to the master unit 1 in synchronization with the slave clock.

[0034] In Figure 2, "Data" represents the generated data flowing through the differential transmission bus. In other words, the beginning of "Data" (i.e., the point when "Data" begins) refers to the time when the transmitter 81 starts transmitting the generated data to the master unit 1. The end of "Data" (i.e., the point when "Data" ends) refers to the time when the transmitter 81 has finished transmitting the generated data to the master unit 1.

[0035] After the transmitter 81 transmits the generated data and the slave clock, the transmitter 81 outputs a transmission completion flag signal (indicated as "Slave clock" in Figure 2; in particular, the flag signal for the part where the Slave clock transitions from on to off at time t30, which will be described later) to the slave clock generator 71.

[0036] Upon receiving the transmission completion flag, the slave clock generator 71 switches from on to off and stops outputting the slave clock. When the slave clock generator 71 switches from on to off, the slave unit SN1 switches from TX mode to RX mode. This time is denoted as time t30. At time t30, after the slave unit SN1 switches from RX mode to TX mode, it waits in a state where it can receive from the master unit 1.

[0037] The slave transceiver ST1 is linked to the operating mode of the slave unit SN1. In other words, when the slave unit SN1 switches from RX mode to TX mode, the slave transceiver ST1 switches from off (e.g., high impedance state) to on (e.g., low impedance state). Conversely, when the slave unit SN1 switches from TX mode to RX mode, the slave transceiver ST1 switches from on to off.

[0038] Similarly, when the master unit switches from TX mode to RX mode, the master transceiver MT switches from on (e.g., low impedance state) to off (e.g., high impedance state). Then, when the master unit switches from RX mode to TX mode, the master transceiver MT switches from off to on.

[0039] After the master unit 1 sends a command to the slave unit SN1, that is, after a predetermined number of clock cycles have been counted in the master clock since time t10, the master unit 1 switches from TX mode to RX mode. The number of clock cycles can be obtained, for example, by counting the number of clock pulses in the master clock.

[0040] While the master unit 1 is in RX mode, the master control unit 3 generates the master clock, but no commands are sent to the slave unit 200, so the supply of the master clock to the slave unit 200 is stopped (indicated as "Master clock" Off in Figure 2). While the master unit 1 is in TX mode, the master clock is supplied to the slave unit 200 (indicated as "Master clock" On in Figure 2).

[0041] Here, the method for determining the number of clock cycles for switching must prevent interference between the master clock and the slave clock, and ensure that both the master unit 1 and the slave unit SN1 are in TX mode, so that the transmission of commands and the transmission of generated data do not conflict in terms of timing. Therefore, when the master unit 1 switches from TX mode to RX mode, the number of clock cycles for switching is set to coincide with the time when the slave clock generator 71 turns from off to on, that is, at time t20. After the master unit 1 switches from TX mode to RX mode, it waits in a state where it can receive from the slave unit SN1.

[0042] Then, when the master unit 1 receives generated data from the slave unit SN1 via the master receiver MR, it switches from RX mode to TX mode (switching process A) after recognizing, for example, the end of the generated data. Alternatively, based on the master clock, the master unit 1 may switch from RX mode to TX mode after a predetermined number of clock cycles have passed since it switched from TX mode to RX mode (switching process B).

[0043] In this case, when setting the number of clock cycles in advance, as in switching process B, it is necessary to set it to a relatively long duration, taking into account the waiting time that accounts for fluctuations in the processing time and processing time delays of the slave unit SN1. Therefore, it is expected that in the case of switching process A, where the master unit 1 resumes sending commands in response to the reception of generated data from the slave unit SN1, the time during which command transmission is stopped will be shorter and processing will be smoother.

[0044] Furthermore, the master unit 1 may recognize the end of the generated data received from the slave unit SN1 by recognizing an end flag indicating the end position of the data embedded in the generated data, or by recognizing that there is empty data of a predetermined length after the data at the end position in the generated data.

[0045] After the master unit 1 switches to TX mode, the master unit 1 sends a command containing control data (labeled "Control command" in Figure 2) to the slave unit SN1. The time it takes for the master unit 1 to resume sending commands, including the request data, to the slave unit SN1 is determined by the specifications regarding the time it takes for the master clock played back in the CDR unit 41 to stabilize.

[0046] When the master unit 1 sends a command containing control data to the slave unit SN1, the master unit 1 operates in TX mode and the slave unit SN1 operates in RX mode. In other words, the modes of the master unit 1 and the slave unit SN1 do not switch from their initial states, and the slave unit SN1 processes the control data using the master clock.

[0047] Next, the operation of the notification system 100 in the embodiment 1 configured as described above will be explained using Figure 3. Figure 3 is a flowchart showing the processing flow of a slave unit 200 (referred to here as slave unit SN1) in the communication system 100 after it receives a command from the master unit 1, the received command is separated into instruction data including the master clock and slave ID by the CDR unit 41, and then reconstructed by the slave unit SN1.

[0048] First, the slave control unit 51 determines whether the slave ID included in the instruction data is SN1 (step S10). If the slave ID is SN1 and matches the ID of the slave unit SN1, it determines whether the command received from the master unit 1 contains request data (step S11). If the command does not contain request data, that is, if it is control data instead of request data, it receives a command (step S20), and the slave control unit 51 performs the processing instructed by the control data based on the received control data (step S21).

[0049] If the command received from the master unit 1 includes request data, the slave control unit 51 writes the request data to the memory 61 using the master clock (step S12). After the request data is written to the memory 61, the slave control unit 51 outputs a write completion flag signal to the slave clock generator 71. Upon receiving the write completion flag, the slave clock generator 71 switches from off to on and outputs the slave clock (step S13).

[0050] The slave clock output from the slave clock generation unit 71 is output to the memory 61 and the transmission unit 81, and the memory 61 and the transmission unit 81 operate using the slave clock, respectively. The transmitting unit 81 reads the request data from the memory 61 in synchronization with the slave clock, and generates generated data using a read data generation unit (not shown) according to the request data. After generating the generated data, the transmitting unit 81 transmits the generated data to the master unit 1 in synchronization with the slave clock (step S14).

[0051] After transmitting the generated data, the transmission unit 81 outputs a transmission completion flag signal to the slave clock generation unit 71. Upon receiving the transmission completion flag signal, the slave clock generation unit 71 switches from on to off (step S15). The slave clock generation unit 71 stops outputting the slave clock, and the series of processes is completed.

[0052] Furthermore, after the master unit 1 sends a command containing the request data to the slave unit SN1, it temporarily stops sending commands to the slave unit 200. Subsequently, the master unit 1 determines whether or not it can resume sending commands based on whether or not it has received generated data from the slave unit SN1. Alternatively, after sending a command containing the request data to the slave unit SN1, the system may determine whether to resume sending the command based on whether a predetermined number of clock cycles have elapsed, using the master clock as a guide.

[0053] Thus, after receiving generated data from the slave unit SN1, or after a predetermined number of clock cycles have elapsed since sending a command containing request data to the slave unit SN1, the master unit 1 determines that it is possible to send a command. Subsequently, the master unit 1 resumes sending commands to the slave unit 200. For example, the master unit 1 may sequentially send commands containing request data to other slave units SN2, which are different from the slave unit SN1, at different timings that do not overlap.

[0054] This allows the slave unit to receive commands from the master unit in sync with the master clock, and to transmit generated data from the slave unit to the master unit in sync with the slave clock. By adopting the configuration described above and switching the clock used, it is also possible to transmit data from the slave unit to the master unit even without a master clock. Furthermore, by connecting the master unit and each slave unit to a pair of differential transmission buses, the wiring structure of the signal transmission path between the master unit and the multiple slave units becomes simpler.

[0055] Embodiment 2. The signal system in Embodiment 2 will be explained using Figure 4. Figure 4 is a diagram showing the transaction timing chart of the communication system 100. The characteristic of Embodiment 2 is that the transaction timing of the communication system differs from that of Embodiment 1.

[0056] The configuration of the communication system in Embodiment 2 is basically the same as the configuration of the communication system 100 described in Embodiment 1 with reference to Figure 1. Furthermore, the operation of the communication system in Embodiment 2 is basically the same as the operation of the communication system 100 described in Embodiment 1 with reference to Figure 3. Therefore, the explanation of these configurations and operations, which are basically the same as those in Embodiment 1, will be omitted in Embodiment 2.

[0057] In Figure 4, (a) shows the transmission interval and timing for each command and data, (b) shows the operating mode of the master unit, (c) shows the operating mode of the slave unit, (d) shows the timing of the master clock, and (e) shows the timing of the slave clock.

[0058] In Embodiment 1, the slave unit SN1 is configured to switch from RX mode to TX mode when the slave clock generation unit 71 switches from off to on. However, in Embodiment 2, as shown in Figure 4, the switch from RX mode to TX mode occurs at time t21 when the transmission unit 81 generates the generated data and begins transmitting the generated data.

[0059] Generally, power consumption in TX mode is greater than power consumption in RX mode, so shortening the duration of TX mode can be expected to reduce the overall power consumption of the system. Accordingly, according to Embodiment 2, in addition to the same effects as Embodiment 1, the duration of TX mode for the slave unit SN1 is shortened, which provides the effect of reducing power consumption in the slave unit SN1.

[0060] Furthermore, if request data is sent from master unit 1 to slave units SN1 and SN2, for example, if slave unit SN1 operates at the timing of the transaction shown in Figure 2 and slave unit SN2 operates at the timing shown in Figure 4, the timing of each slave unit sending generated data to master unit 1 can be avoided. As a result, master unit 1 can also send commands containing request data to multiple slave units 200.

[0061] In the embodiments described above, the relationship between the master unit 1 and the slave unit SN1 was shown. However, the slave unit 200 that is related to the master unit 1 is identified and changes by the slave ID. However, the operation of each is the same as the operation between the master unit 1 and the slave unit SN1. Specifically, the operation between the master unit 1 and the slave unit SN2, ..., and the operation between the master unit 1 and the slave unit SNn are the same as the operation between the master unit 1 and the slave unit SN1.

[0062] Furthermore, the operation of the CDR unit 4, slave control unit 5, memory 6, slave clock generation unit 7, and transmission unit 8 in each slave unit 200 is the same as the operation of the CDR unit 41, slave control unit 51, memory 61, slave clock generation unit 71, and transmission unit 81 in slave unit SN1. The operation of the slave transceiver ST and slave receiver SR in each slave unit 200 is also the same as the operation of the slave transceiver ST1 and slave receiver SR1 in slave unit SN1. Therefore, a detailed explanation of the operation of each slave unit in slave unit 200 other than slave unit SN1 is omitted.

[0063] The configurations shown in the above embodiments are examples and can be combined with other known technologies. Furthermore, it is possible to omit or modify parts of the configuration without departing from the spirit of the invention.

[0064] The various aspects of this disclosure are summarized below as an appendix. (Note 1) A master unit that sends a command including a slave ID, a master clock, and instruction data, and temporarily stops sending the command if the instruction data is request data, A slave unit having a slave clock generator that outputs a slave clock and a memory, receiving the command transmitted from the master unit, and if the slave ID matches its own slave ID and the instruction data is the request data, it writes the request data to the memory using the master clock, reads the request data written to the memory using the slave clock output from the slave clock generator, and transmits generated data generated based on the request data to the master unit, A communication system equipped with [the following features]. (Note 2) The communication system according to Appendix 1, characterized in that the slave clock generation unit starts outputting a slave clock after writing the request data to the memory, and stops outputting a slave clock after the generated data has been transmitted from the slave unit to the master unit. (Note 3) The communication system according to Appendix 1, characterized in that the master unit, after transmitting the request data to the slave unit, determines the timing for resuming the transmission of the command based on the slave clock or the master clock. (Note 4) The communication system according to Appendix 1, characterized in that the slave unit receives the command including the request data from the master unit, writes the request data to the memory using the master clock, switches from the master clock to the slave clock to read the request data, and transmits the generated data to the master unit based on the request data. (Note 5) The communication system according to Appendix 1, further comprising a differential transmission bus, wherein the master unit and the slave unit are connected using the differential transmission bus. (Note 6) The communication system according to Appendix 1, further comprising a clock data recovery unit, wherein the command is separated into the master clock and the instruction data using the clock data recovery unit, and the instruction data is regenerated using the master clock. (Note 7) The steps include determining whether the slave ID included in the command transmitted by the master unit to the slave unit, which includes the slave ID, master clock, and instruction data, matches the slave ID of the slave unit itself, If the slave ID matches its own slave ID, the step is to determine whether the instruction data is request data. If the instruction data is request data, the step of writing the request data to memory using the master clock included in the command, After writing the aforementioned request data to the memory, the slave clock generation unit is switched from off to on to generate a slave clock. After turning on the slave clock generation unit, the steps include reading the request data from the memory using the slave clock and transmitting the generated data generated based on the request data to the master unit, After transmitting the generated data to the master unit, the slave clock generation unit is turned from on to off to stop the slave clock. A communication method that includes [something]. (Note 8) The master unit, after sending a command containing the request data to the slave unit, temporarily stops sending the command; A step of determining whether or not the transmission of the command can be resumed based on whether or not the generated data has been received, or based on the master clock, After determining that it is possible to resume sending the command, the step of resuming sending the command to the slave unit, The communication method described in Appendix 7, characterized by having the following features. (Note 9) The master unit, after sending a command containing the request data to the slave unit, temporarily stops sending the command; The steps include: restarting the transmission of the command to the slave unit based on whether or not the generated data has been received, or based on the master clock; The communication method described in Appendix 7, characterized by having the following features. [Explanation of symbols]

[0065] 100 Communication system, 1 Master unit, 200 Slave unit, 3 Master control unit, 4 (41, 42, 43, 4n) CDR unit, 5 (51, 52, 53, 5n) Slave control unit, 6 (61, 62, 63, 6n) Memory, 7 (71, 72, 73, 7n) Slave clock generation unit, 8 (81, 82, 83, 8n) Transmitter unit.

Claims

1. A master unit that sends a command including a slave ID, a master clock, and instruction data, and temporarily stops sending the command if the instruction data is request data, A slave unit having a slave clock generator that outputs a slave clock and a memory, receiving the command transmitted from the master unit, and if the slave ID matches its own slave ID and the instruction data is the request data, it writes the request data to the memory using the master clock, reads the request data written to the memory using the slave clock output from the slave clock generator, and transmits generated data generated based on the request data to the master unit, A communication system equipped with [the following features].

2. The communication system according to claim 1, characterized in that the slave clock generation unit starts outputting the slave clock after writing the request data to the memory, and stops outputting the slave clock after the generated data has been transmitted from the slave unit to the master unit.

3. The communication system according to claim 1, characterized in that the master unit, after transmitting the request data to the slave unit, determines the timing for resuming the transmission of the command based on the slave clock or the master clock.

4. The communication system according to claim 1, characterized in that the slave unit receives the command including the request data from the master unit, writes the request data to the memory using the master clock, switches from the master clock to the slave clock to read the request data, and transmits the generated data to the master unit based on the request data.

5. The communication system according to claim 1, further comprising a differential transmission bus, wherein the master unit and the slave unit are connected using the differential transmission bus.

6. The communication system according to claim 1, further comprising a clock data recovery unit, wherein the command is separated into the master clock and the instruction data using the clock data recovery unit, and the instruction data is regenerated using the master clock.

7. The steps include determining whether the slave ID included in the command transmitted by the master unit to the slave unit, which includes the slave ID, master clock, and instruction data, matches the slave ID of the master unit, If the slave ID matches its own slave ID, the step is to determine whether the instruction data is request data. If the instruction data is request data, the step of writing the request data to memory using the master clock included in the command, After writing the aforementioned request data to the memory, the slave clock generation unit is switched from off to on to generate a slave clock. After turning on the slave clock generation unit, the steps include reading the request data from the memory using the slave clock and transmitting the generated data generated based on the request data to the master unit, After transmitting the generated data to the master unit, the slave clock generation unit is turned from on to off to stop the slave clock. A communication method that includes [something].

8. The master unit, after sending a command containing the request data to the slave unit, temporarily stops sending the command; A step of determining whether or not the transmission of the command can be resumed based on whether or not the generated data has been received, or based on the master clock, After determining that it is possible to resume sending the command, the step of resuming sending the command to the slave unit, The communication method according to claim 7, characterized by having the following features.

9. The master unit, after sending a command containing the request data to the slave unit, temporarily stops sending the command; The steps include: restarting the transmission of the command to the slave unit based on whether or not the generated data has been received, or based on the master clock; The communication method according to claim 7, characterized by having the following features.

Images