JP2005352352A - Control system by serial communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control system by serial communication that can suppress the increase of the number of ports used in the control device selecting the devices to be controlled and the total signal line length. <P>SOLUTION: The serial/parallel converter circuits are connected together in series by using serial chip select lines in multiple stage units to be controlled and their parallel output terminals are respectively connected to the devices to be controlled. The controller transmits the serial chip select data signals through the serial chip select lines to make them reach all the stages of the serial/parallel converter circuit from the first to the last stages. Thus by activating the desired ones out of the parallel output terminals in this way, the controller selects at least one of the units to be controlled as a control target. Then the controller exchanges the data between the selected control targets. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control system using serial communication in which a control device controls a controlled device using serial communication.

  In FIG. 1 and FIG. 3 of the following Patent Document 1, a plurality of card boards 3A... 3N on which a plurality of controlled devices (ICs) 11A to 11M are mounted, and a CPU that is a control device of the controlled devices 11A to 11M. (Central Processing Unit) 5 is shown. An address decoder 15 is provided on each card substrate. Furthermore, serial interfaces (SIF) 20A to 20M are provided in the controlled devices 11A to 11M, respectively.

  In the above technique, the address data ADD, which is card board designating data, and the IC address ICADDi (i = 1 to m), which is controlled device designating data, are serially transmitted from the CPU 5, so that a plurality of cards can be obtained. Chip selection for selecting one of a plurality of controlled devices among one of the substrates is performed. This is because a description of “a serial identification signal including an identification signal for specifying a board and an identification signal for specifying an IC is sent from the CPU” in paragraph 0015 of Patent Document 1, and paragraph 0033 In the above, “a specific IC in a specific card board is selected by the serial identification signal sent from the CPU and each coincidence detecting means”.

  Specifically, the address decoder 15 receives the address data ADD and outputs a chip select signal CS to select one card board (from the description in the 0019th paragraph and the 0022th paragraph). Then, the serial interfaces 20A to 20M in the controlled devices 11A to 11M receive the IC address ICADDi and determine whether or not they are designated (from the description in the paragraph 0024).

  Thus, in the above technique, an arbitrary controlled device is selected by serial communication.

JP-A-5-284390

  In the above-mentioned patent document 1, since the configuration in which all the IC addresses ICADDi are output from the CPU 5 is adopted, it is necessary to prepare output ports in the CPU 5 by the number of the IC addresses ICADDi. In other words, the output ports of the CPU 5 are consumed by the number of controlled devices 11A to 11M to be connected.

  Further, since it is necessary to route each signal line of the IC address ICADDi to each of the controlled devices 11A to 11M, the total signal line length becomes a large value, and the cost required for the signal line is increased.

  In Patent Document 1, a mixer circuit board or the like in a video editing apparatus is assumed as a target of a plurality of card boards (from the description in paragraph 0002). Therefore, in order to give each signal of the IC address ICADDi to each of the controlled devices 11A to 11M, a printed wiring may be employed as the signal line, and the printed wiring length may be increased to some extent.

  However, in the above configuration in which the control device controls the controlled device by serial communication, for example, a microcomputer (corresponding to the control device) in a large-sized video display device in a baseball stadium is composed of light emitting elements (light emitting diodes, etc.) The present invention can also be applied when controlling a plurality of display units (corresponding to controlled devices). In such a case, since it is a large-sized device, printed wiring cannot be used as a serial signal line, and a communication cable must be used.

  The present invention has been made in view of the above circumstances, and provides a control system based on serial communication capable of suppressing an increase in the number of port consumption of a control device and the total signal line length necessary for selection of a controlled device. Objective.

  The present invention includes a control device, a plurality of stages of controlled units, a data line, and a first serial chip select line. Each of the plurality of stages of controlled units includes a serial input terminal, a serial output terminal, and a serial output terminal. A first serial / parallel conversion circuit having a parallel output terminal; and a plurality of first controlled devices respectively connected to the terminals of the parallel output terminal of the first serial / parallel conversion circuit, The data line connects all of the first controlled devices and the control device over all of the plurality of controlled units, and the first serial chip select line connects the preceding serial output terminal and the succeeding stage. By connecting the serial input terminal, the first serial / parallel conversion circuits in the plurality of stages of controlled units are connected in series, and the control device is connected. Transmits a first chip select data signal, which is a serial signal, via the first serial chip select line so as to reach from the first stage to the last stage of the first serial / parallel conversion circuits connected in series. Then, by activating a desired terminal of the parallel output terminals, at least one of the plurality of first controlled devices can be selected as a first control target, and the selected It is a control system by serial communication for exchanging data with the first controlled object via the data line.

  According to the present invention, the control device transmits the first chip select data signal via the first serial chip select line, and selects a desired terminal of the parallel output terminals of the first serial / parallel conversion circuit. By activating, at least one of the plurality of first controlled devices can be selected as the first control target. Therefore, it is not necessary to draw out the same number of chip select lines as the first controlled device from the control device, and the first control target can be selected using the first serial chip select line. Thereby, it is possible to suppress an increase in the number of ports consumed by the control device. A plurality of first controlled devices are connected to each terminal of the parallel output terminal of the first serial / parallel conversion circuit. Therefore, it is possible to suppress an increase in the total signal line length as compared with a case where a chip select line is pulled out from the control device for each of the plurality of first controlled devices.

<Embodiment 1>
In the present embodiment, a control device transmits a chip select data signal via a serial chip select line, and activates a desired terminal among the parallel output terminals of the serial / parallel converter circuit, whereby a plurality of signals are received. This is a control system based on serial communication in which at least one control device can be selected as a control target.

  FIG. 1 is a diagram showing a configuration of a control system by serial communication according to the present embodiment. In the present embodiment, the case where the control system is applied to a large video display device in a baseball field or the like will be taken as an example. Therefore, the control system according to the present embodiment is represented as a video display module 25a that functions as a component of a large video display device. The large screen of the large video display device is configured by regularly combining a plurality of video display modules 25a vertically and horizontally.

  As shown in FIG. 1, the video display module 25a includes a first display unit device 3a, a second display unit device 4a,..., An Nth (N is a natural number) display unit device (not shown) as a plurality of controlled units. And a unit control device 1 which is a control device thereof. Each stage of the first to Nth display unit devices functions as one block constituting the video display module 25a.

  The unit control apparatus 1 has a microcomputer 2 that is a master device that assumes the serial data communication function. The first display unit 3a includes a serial / parallel conversion circuit 7 for generating a chip select signal, and a controlled serial communication IC (Integrated Circuit) 11 which is n controlled devices (A1 to An: n is a natural number). ~ 13. The parallel conversion circuit 7 has a serial input end, a serial output end, and a parallel output end.

  Here, the controlled serial communication ICs 11 to 13 are slave devices in the first display unit device 3a controlled by the microcomputer 2, for example, a plurality of light emitting diodes (three pixels of RGB are used as one pixel). , A temperature sensor IC that provides temperature information in the first display unit device 3a, a non-volatile memory IC for storing information such as luminance correction values in the first display unit device 3a, etc. It is.

  A large video display device appears to have only a simple video display function, but not only the video display function, but also various functions for improving display quality and device reliability. The function is working.

  For example, in order to absorb variations in luminous intensity for each dot of the light emitting display element, a correction value that makes the display brightness of the dots of all the light emitting display elements constant is stored in advance in a nonvolatile memory IC provided in the display unit device. In addition, there is a function of improving the display quality by making the luminance of the display surface uniform by using this correction value during video display. Further, the microcomputer 2 acquires temperature information from the temperature sensor IC provided in the display unit device, and when the temperature in the display unit device exceeds an allowable range due to an accident or the like, the brightness is lowered and the display unit device is consumed. There is also a function of improving reliability by reducing electric power and suppressing temperature rise.

  The controlled serial communication ICs 11 to 13 are controlled devices controlled by the microcomputer 2 in order to realize a video display function and other various functions.

  The second display unit device 4a is also a serial / parallel conversion circuit 16 similar to the serial / parallel conversion circuit 7, and n (B1 to Bn) controlled devices similar to the controlled serial communication ICs 11 to 13. And control serial communication ICs 20 to 22. Similarly, other Nth display unit devices (not shown) have a serial / parallel conversion circuit and n controlled serial communication ICs.

  The microcomputer 2 in the unit control device 1 and all of the controlled serial communication ICs (including reference numerals 11 to 13, 20 to 22 and those not shown) are SPI (Serial Peripheral Interface) data lines. 5, 14 and 23 are connected across all of the first to Nth display unit devices. The SPI data lines 5, 14, and 23 include three lines: a serial clock CLK communication line, a serial output data SDO communication line, and a serial input data SDI communication line.

  In order to realize the above-described video display function, temperature control function, and other various functions, a serial clock is directed from the microcomputer 2 to a specific controlled serial communication IC chip-selected (described later) in the video display module 25a. CLK and serial input data SDI are output, and serial output data SDO is output from the controlled serial communication IC to the microcomputer 2.

  The microcomputer 2 and the first serial / parallel conversion circuit 7 are connected by a three-line serial chip select data line 6. Further, the serial output terminal of the first stage serial / parallel converter circuit 7 and the serial input terminal of the second stage serial / parallel converter circuit 16 are connected by the serial chip select data line 15.

  Similarly, the serial output terminal of the second-stage serial / parallel conversion circuit 16 and the serial input terminal of the third-stage serial / parallel conversion circuit (not shown) are connected by the serial chip select data line 24. . That is, the serial output terminals of the first serial / parallel conversion circuit and the serial input terminal of the subsequent serial / parallel conversion circuit are connected to each other, so that the serial / parallel conversion circuits in the first to Nth display unit devices are connected to each other. Connected in series.

  In the first display unit device 3a, controlled serial communication ICs 11 to 13 are connected to the terminals of the parallel output terminal of the serial / parallel conversion circuit 7, respectively. Similarly, in the second display unit device 4a, controlled serial communication ICs 20 to 22 are connected to the terminals of the parallel output terminal of the serial / parallel conversion circuit 16, respectively. Similarly, in other Nth display unit devices not shown, n controlled serial communication ICs are connected to the respective terminals of the parallel output terminal of the serial / parallel conversion circuit.

  The serial chip select data lines 6, 15 and 24 include three lines: a communication line for chip select serial clock CS_CLK, a communication line for chip select serial latch CS_LAT, and a communication line for chip select serial data CS_DAT.

  FIG. 2 is a diagram showing a configuration of a serial / parallel conversion circuit (including reference numerals 7 and 16 and other components not shown) in the control system of the present embodiment. In FIG. 2, the serial / parallel conversion circuit 7 (in the parentheses is the case of the serial / parallel conversion circuit 16) is described as an example.

  As shown in FIG. 2, the serial / parallel conversion circuit 7 latches the outputs of the D flip-flops 29, 30, 30a to 30d, 31 and the D flip-flops 29, 30, 30a to 30d, 31 constituting the shift register, respectively. Latch circuits 32, 33, 33a to 33d, 34.

  Also, three serial chip select data lines 6 are input to the serial / parallel conversion circuit 7. Of the serial chip select data line 6, the communication line 27 of the chip select serial clock CS_CLK is connected to the clock input terminal of any of the D flip-flops 29, 30, 30a to 30d, 31 and the communication line of the chip select serial latch CS_LAT. 28 is connected to any latch signal input terminal of the latch circuits 32, 33, 33 a to 33 d, 34.

  Of the serial chip select data lines 6, the communication line 26 for chip select serial data CS_DAT is connected to the data input terminal D of the D flip-flop 29 which is the first stage of the shift register. A communication line for chip select serial data CS_DAT extends again from the data output terminal Q of the D flip-flop 31 which is the final stage of the shift register.

  The three lines of the chip select serial data CS_DAT communication line from the D flip-flop 31, the chip select serial clock CS_CLK communication line penetrating the serial / parallel conversion circuit 7, and the chip select serial latch CS_LAT communication line are: The serial chip select data line 15 to the second-stage serial / parallel conversion circuit 16 is configured.

  The output terminals of the latch circuits 32, 33, 33a to 33d, and 34 constitute the terminals of the parallel output terminal of the serial / parallel conversion circuit 7, and the signal lines 8, 9, 9a to 9d, 10 is connected.

  Each signal line 8, 9, 9a to 9d, 10 is connected to the controlled serial communication ICs 11 to 13 (see FIG. 1), and the chip select signals CS1, CS2,. 13 is transmitted.

  Chip select for selecting a controlled serial communication IC to be a communication destination before the microcomputer 2 exchanges data via the SPI data lines 5, 14, and 23 in the video display module 25a will be described below. explain. Here, a case where the microcomputer 2 selects only the controlled serial communication IC 21 in the second display unit device 4a in FIG. 1 is taken as an example.

  FIG. 3 is a timing chart of signals of the chip select serial clock CS_CLK, the chip select serial latch CS_LAT, and the chip select serial data CS_DAT included in the three lines of serial chip select data lines 6, 15, 24. In the figure, time advances from “start” to “end”.

  The microcomputer 2 includes the number of controlled serial communication ICs included in the Nth display unit device,..., The number of controlled serial communication ICs 20 to 22 included in the second display unit device 4a, and the first display unit device 3a. Clock pulses corresponding to the total number of controlled serial communication ICs 11 to 13 are sequentially generated as a chip select serial clock CS_CLK. A clock pulse is generated from the portion of the Nth display unit device corresponding to the final stage. In FIG. 3, the rising edge of the chip select serial clock CS_CLK is used as a trigger.

  Each of the D flip-flops 29, 30, 30a to 30d, 31 in FIG. 2 receives the clock pulse train of the chip select serial clock CS_CLK and transmits the signal at the data input terminal D to the data output terminal Q every clock cycle. .

  The chip select serial clock CS_CLK includes clock pulses corresponding to the total number of controlled serial communication ICs in the Nth to first display unit devices. Therefore, the sequentially generated clock pulses correspond to the controlled serial communication ICs included in the Nth to first display unit devices, respectively. In FIG. 3, this is shown by adding chip select signals CS1 to CSn in each display unit device.

  The microcomputer 2 also generates chip select serial data CS_DAT so that it becomes active only in synchronization with the clock pulse corresponding to the controlled serial communication IC 21 in the second display unit device 4a to be chip selected. The microcomputer 2 generates a clock pulse corresponding to the controlled serial communication IC 11 included in the first display unit device 3a, and then generates a latch pulse as a chip select serial latch CS_LAT.

  Each of the D flip-flops 29, 30, 30a to 30d, and 31 in FIG. 2 sequentially transmits the chip select serial data CS_DAT applied to the data input terminal D to the next stage every clock cycle. Therefore, finally, only the data output terminal Q of the D flip-flop corresponding to the controlled serial communication IC 21 in the second display unit device 4a to be chip-selected is active.

  Then, when the chip select serial latch CS_LAT becomes active, the latch circuits 32, 33, 33a to 33d and 34 in FIG. 2 are connected to the data output terminals of the corresponding D flip-flops 29, 30, 30a to 30d and 31, respectively. The signal at Q is latched and transmitted to each controlled serial communication IC as the chip select signals CS1 to CSn via the signal lines 8, 9, 9a to 9d and 10. Thereby, only the controlled serial communication IC 21 in the second display unit device 4a is selected.

  That is, the microcomputer 2 transmits the chip select serial data CS_DAT, which is a serial signal, from the first stage to the last stage of the serial / parallel conversion circuit connected in series between the first to Nth display unit devices. The data is transmitted via the select data lines 6, 15 and 24, and a desired terminal among the parallel output terminals of the serial / parallel conversion circuit of each stage is activated. Thus, a specific one of the controlled serial communication ICs can be selected as a control target, and the microcomputer 2 can communicate with the selected control target via the SPI data lines 5, 14, and 23. Exchange data.

  When performing communication with a specific controlled serial communication IC, the length of clock pulses of all the controlled serial communication ICs (N × n) of the first to Nth display unit devices is each time. It is necessary to transmit the chip select serial data CS_DAT to the serial / parallel conversion circuit in each stage.

  According to the control system of the present embodiment, it is not necessary to draw out the same number of chip select lines as the controlled serial communication IC from the unit control device 1, and the serial chip select data line 6 including the communication line of the chip select serial data CS_DAT. , 15, 24 can be used to select a control target. Thereby, the increase in the number of port consumptions of the unit control apparatus 1 can be suppressed.

  A plurality of controlled serial communication ICs are connected to each terminal at the parallel output terminal of the serial / parallel conversion circuit. Therefore, it is possible to suppress an increase in the total signal line length as compared with the case where a chip select line is pulled out from the unit control device 1 for each of a plurality of controlled serial communication ICs.

<Embodiment 2>
The present embodiment is a modification of the control system using serial communication according to the first embodiment, and another similar communication line different from the chip select serial data CS_DAT communication line in the first embodiment is used. The serial / parallel conversion circuit is also connected to the increased communication line and the additional communication line.

  FIG. 4 is a diagram showing a control system by serial communication according to the present embodiment. 4, the first display unit device 3a, the second display unit device 4a,..., The same as the Nth display unit device, the first display unit device 3b, the second display unit device 4b,. A display unit device is provided.

  However, the first display unit device 3b is provided with a serial / parallel conversion circuit 7b in addition to the serial / parallel conversion circuit 7a. Of the n controlled serial communication ICs, 1 to k-th (reference numerals 11 to 13) are connected to the parallel output terminals of the serial / parallel conversion circuit 7a via signal lines 8a to 10a, and k to n. (Reference numerals 35 to 37) are connected to the parallel output terminal of the serial / parallel conversion circuit 7b via signal lines 8b to 10b.

  The same applies to the second display unit device 4b, and a serial / parallel conversion circuit 16b is provided in addition to the serial / parallel conversion circuit 16a. 20 to 22) are connected to the parallel output end of the serial / parallel conversion circuit 16a via signal lines 17a to 19a, and k to nth (reference numerals 38 to 40) are connected to the parallel output end of the serial / parallel conversion circuit 16b. The signal lines 17b to 19b are connected. The same applies to other Nth display unit devices not shown.

  The microcomputer 2 in the unit control device 1 and all of the controlled serial communication ICs (including reference numerals 11 to 13, 35 to 37, 20 to 22, 38 to 40, and other unillustrated ones) All the first to Nth display unit devices are connected by SPI data lines 5, 14, and 23.

  The microcomputer 2 and the first-stage serial / parallel conversion circuit 7a are connected by a three-line serial chip select data line 6. Note that the chip select serial data has been renamed CS_DAT1. A serial chip select data line 15 connects the serial output terminal of the first-stage serial / parallel conversion circuit 7a and the serial input terminal of the second-stage serial / parallel conversion circuit 16a.

  Similarly, the serial output terminal of the second-stage serial / parallel converter circuit 16a and the serial input terminal of the third-stage serial / parallel converter circuit (not shown) are connected by the serial chip select data line 24. . That is, the serial output terminals of the first serial / parallel conversion circuit and the serial input terminal of the subsequent serial / parallel conversion circuit are connected to each other, so that the serial / parallel conversion circuits in the first to Nth display unit devices are connected to each other. Connected in series.

  Further, the microcomputer 2 is also provided with a communication line 41 for the same chip select serial data CS_DAT2 which is different from the chip select serial data CS_DAT1. The microcomputer 2 and the first stage serial / parallel conversion circuit 7 b are connected by a communication line 41. Note that the communication line of the chip select serial clock CS_CLK and the communication line of the chip select serial latch CS_LAT branched from the serial chip select data line 6 are also connected to the serial / parallel conversion circuit 7b.

  Further, the serial output terminal of the first stage serial / parallel conversion circuit 7b and the serial input terminal of the second stage serial / parallel conversion circuit 16b are connected by the communication line 42 of the chip select serial data CS_DAT2. Note that the communication line of the chip select serial clock CS_CLK and the communication line of the chip select serial latch CS_LAT branched from the serial chip select data line 15 are also connected to the serial / parallel conversion circuit 16b.

  Similarly, the serial output terminal of the second-stage serial / parallel converter circuit 16b and the serial input terminal of the third-stage serial / parallel converter circuit (not shown) are connected by the communication line 43 of the chip select serial data CS_DAT2. Has been. That is, by connecting the serial output terminal of the serial / parallel conversion circuit in the preceding stage and the serial input terminal of the serial / parallel conversion circuit in the subsequent stage, serial / parallel conversion of different systems in the first to Nth display unit devices. The circuits are connected in series.

  Since other points are the same as those of the control system according to the first embodiment, description thereof is omitted.

  The control system according to the present embodiment further includes a communication line 41 for chip select serial data CS_DAT2 that is different from the communication line for chip select serial data CS_DAT1, and is connected via serial / parallel conversion circuits 7b and 16b. A control target can also be selected from the control serial communication ICs 35-40. Therefore, two control systems can be realized, and the number of controlled serial communication ICs on the communication line side of chip select serial data CS_DAT1 is reduced to k−1 per display unit device, and the reduced amount is chip select serial. By using the controlled serial communication IC on the communication line side of the data CS_DAT2, the time required for the chip select serial data CS_DAT to be distributed from the first stage to the last stage of the serial / parallel conversion circuits 7a and 16a connected in series is shortened. Can do.

  Thereby, both the communication line side of the chip select serial data CS_DAT1 and the communication line side of the chip select serial data CS_DAT2 reduce the time required for selecting the control target, and the operation speed can be increased.

  Specifically, for example, when k = n / 2 + 1, that is, when the number of controlled serial communication ICs connected to each of the serial / parallel conversion circuits 7a and 7b is the same, communication with a specific controlled serial communication IC is performed. When performing, all controlled serial communication ICs of the first to Nth display unit devices each time on the communication line side of the chip select serial data CS_DAT1 and the communication line side of the chip select serial data CS_DAT2 Chip select serial data CS_DAT1 and CS_DAT2 having a length corresponding to (N × n / 2) clock pulses may be transmitted to the serial / parallel conversion circuit of each stage. Compared with the case where the chip select serial data CS_DAT having a length corresponding to (N × n) clock pulses is generated as in the first embodiment, it is only necessary to generate a signal having a half data length. Can be achieved.

  In this embodiment, the signal lines of chip select serial data CS_DAT1 and CS_DAT2 are two lines, but a larger number of lines may be used.

<Embodiment 3>
The present embodiment is a modification of the control system using serial communication according to the first embodiment. The controlled serial communication IC in each display unit device according to the first embodiment is connected to the main device and the main device. It is divided into sub-devices with the same function, and the main device is operated during normal operation, and the sub-device is operated instead of the main device when data exchange with the main device occurs. is there.

  In the first embodiment, the controlled serial communication ICs 11 to 13 in the first display unit device 3a are provided to realize the video display function and other various functions, and each of the controlled serial communication ICs 11 to 13 has an individual function. It was a device. However, in the present embodiment, for example, the controlled serial communication IC 11 is a main device having a light emitting display function, and the controlled serial communication IC 13 is a sub-device having exactly the same function as the controlled serial communication IC 11.

  Then, by changing the program of the microcomputer 2, the controlled serial communication IC as the main device in each display unit device is chip-selected during normal operation, while the serial communication with the main device is disabled. When this happens, the sub device, not the main device, is chip-selected.

  Whether the serial communication is disabled is determined by, for example, determining whether the main device has failed and the serial input data SDI from the main device to the microcomputer 2 has been in the Hi or Low state for a predetermined period or more, or For example, a checksum for checking the degree of coincidence of the number of transmission data may be used.

  For example, when the controlled serial communication IC 11 in the first display unit device 3a is a main temperature sensor and the controlled serial communication IC 13 is a sub temperature sensor, the unit control device 1 has a temperature in the first display unit device 3a. In order to collect data, a temperature information request is made to the controlled serial communication IC 11 by serial communication.

  If the controlled serial communication IC 11 that is the main temperature sensor has failed, the controlled serial communication IC 11 does not react to the microcomputer 2 and is fixed to either Hi or Low as a response to the request. In this state, the signal is output. If the response to the request remains fixed at either Hi or Low for a long period of time, the microcomputer 2 determines that the controlled serial communication IC 11 serving as the main temperature sensor has failed, and the sub temperature sensor Chip select the serial communication IC 13 to be controlled.

  In this way, when a malfunction occurs in data exchange with the main device, the unit control device 1 can select a sub device instead of the main device as a control target. Therefore, a control system with excellent reliability at the time of failure can be realized.

<Embodiment 4>
The present embodiment is a modification of the control system using serial communication according to the first embodiment, in which a three-state gate is provided for each display unit device, and one terminal of the parallel output terminal of the serial / parallel conversion circuit is connected to three states. It is connected to the enable input of the gate.

  FIG. 5 is a diagram showing a control system by serial communication according to the present embodiment. In FIG. 5, a three-state gate and a buffer are provided on the SPI data line in the first to Nth display unit devices. The buffer is a signal amplification stage composed of a complementary metal oxide semiconductor field effect transistor (CMOS) or the like. The three-state gate is a device that cuts off a signal from the display unit device in the subsequent stage when the controlled serial communication IC in the display unit device to which the three-state gate transmits data to the microcomputer 2.

  Taking the first display unit device 3c as an example, the SPI data line 5 from the microcomputer 2 branches to the controlled serial communication ICs 11 to 13 after passing through the buffer 46 in the first display unit device 3c. At the same time, the communication line for the serial clock CLK and the communication line for the serial input data SDI in the SPI data line 5 constitute the SPI data line 14 to the next stage via the buffer 47.

  On the other hand, the serial output data SDO communication line constitutes one line in the SPI data line 14, passes through the buffer 47 and then passes through the three-state gate 44, and passes through the buffer 46 to the microcomputer 2. The data line 5 is configured.

  The enable input section of the three-state gate 44 is connected to the terminal of the chip select signal CS1 at the parallel output end of the serial / parallel conversion circuit 7 via the signal line 8. The signal lines 9 and 10 after the chip select signal CS2 are connected to the controlled serial communication ICs 11 to 13, respectively.

  Similarly, in the second display unit device 4c, buffers 48 and 49 and a three-state gate 45 are provided. The same applies to the Nth display unit device. The apparatus configuration other than those points is the same as that in FIG.

  Between the first to Nth display unit devices, the SPI data lines 5, 14, and 23 connect the signal output unit of the subsequent three-state gate and the signal input unit of the three-state gate of the previous stage, so that 3 The state gates are connected in series.

  Chip select for selecting a controlled serial communication IC to be a communication destination before the microcomputer 2 exchanges data via the SPI data lines 5, 14, and 23 in the video display module 25c will be described below. explain. Here, a case where the microcomputer 2 selects only the controlled serial communication IC 21 in the second display unit device 4c in FIG. 5 is taken as an example.

  FIG. 6 is a timing chart of signals of the chip select serial clock CS_CLK, the chip select serial latch CS_LAT, and the chip select serial data CS_DAT included in the three lines of serial chip select data lines 6, 15, and 24. In FIG. 6, only the point that the chip select serial data CS_DAT is active not only in the corresponding part of the chip select signal CS2 but also in the corresponding part of the chip select signal CS1 which is an LSB (Least Significant Bit). And different.

  Thus, when the microcomputer 2 reads data from the controlled serial communication IC 21 in the second display unit device 4c to be chip-selected, the microcomputer 2 activates the terminal corresponding to the chip select signal CS1 at the parallel output terminal. (Hi active) is also performed.

  Then, the enable input portion of the three-state gate 45 connected to the signal line 17 is deactivated (the three-state gate 45 is set to low active), and the three-state gate 45 enters a high impedance output state. On the other hand, the other three-state gates are in the data through state. As a result, indefinite data on the SPI data line 23 that is positioned after the second display unit device 4 c including the controlled serial communication IC 21 that has been chip-selected is prevented from reaching the microcomputer 2. Therefore, it is difficult for noise to enter the data from the controlled serial communication IC 21.

  Since other points are the same as those of the control system using serial communication according to the first embodiment, description thereof is omitted.

  According to the control system according to the present embodiment, it is difficult for noise to enter the data from the selected controlled serial communication IC, and the signal transmission reliability is high.

1 is a diagram illustrating a configuration of a control system using serial communication according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a configuration of a serial / parallel conversion circuit in the control system according to the first embodiment. 4 is a timing chart of signals of a chip select serial clock CS_CLK, a chip select serial latch CS_LAT, and chip select serial data CS_DAT in the control system according to the first embodiment. It is a figure which shows the structure of the control system by serial communication which concerns on Embodiment 2. FIG. FIG. 10 is a diagram illustrating a control system using serial communication according to a fourth embodiment. 14 is a timing chart of signals of a chip select serial clock CS_CLK, a chip select serial latch CS_LAT, and a chip select serial data CS_DAT in the control system according to the fourth embodiment.

Explanation of symbols

1 Unit control device, 3a, 3b, 4a, 4b Display unit device, 5, 14, 23 SPI data line, 6, 15, 24, 41-43 Serial chip select data line, 7, 7a, 7b, 16, 16a, 16b Serial / parallel conversion circuit, 11-13, 20-22, 35-37, 38-40 Controlled serial communication IC, 44, 45 3-state gate.

Claims (4)

A control device;
A multi-stage controlled unit;
Data lines,
A first serial chip select line;
Each of the plurality of stages of controlled units includes a first serial / parallel conversion circuit having a serial input end, a serial output end, and a parallel output end, and each of the parallel output ends of the first serial / parallel conversion circuit. A plurality of first controlled devices respectively connected to the terminals,
The data line connects all of the first controlled devices and the control device across all of the plurality of controlled units,
By connecting the first serial output terminal and the second serial input terminal to each other by the first serial chip select line, the first serial / parallel conversion circuits in the plurality of stages of controlled units are connected to each other. Connected in series,
The control device sets the first serial chip select line so that the first chip select data signal as a serial signal is distributed from the first stage to the last stage of the first serial / parallel conversion circuit connected in series. And at least one of the plurality of first controlled devices can be selected as a first control target by activating a desired terminal of the parallel output terminals. A control system using serial communication for exchanging data with the first controlled object via the data line. A control system using serial communication according to claim 1,
A second serial chip select line of a different system from the first serial chip select line;
Each of the plurality of stages of controlled units includes a second serial / parallel conversion circuit having a serial input end, a serial output end, and a parallel output end, and each of the parallel output ends of the second serial / parallel conversion circuit. A plurality of second controlled devices respectively connected to the terminals,
The data line also connects all of the second controlled devices and the control device across all the controlled units of the plurality of stages,
The second serial chip select line connects the serial output terminal in the preceding stage and the serial input terminal in the subsequent stage, so that the second serial / parallel conversion circuits in the plurality of stages of controlled units are connected to each other. Connected in series,
The control device sets the second serial chip select line so that the second chip select data signal as a serial signal is distributed from the first stage to the last stage of the second serial / parallel conversion circuit connected in series. And at least one of the plurality of second controlled devices can be selected as a second control target by activating a desired terminal of the parallel output terminals. A control system by serial communication for exchanging data via the data line even with the second controlled object. A control system using serial communication according to claim 1,
The plurality of first controlled devices include a main device and a sub device having the same function as the main device,
During normal operation, the control device selects the main device as the first control object,
When a malfunction occurs in data exchange with the main device, the control device is a control system by serial communication that selects the sub device instead of the main device as the first control target. A control system using serial communication according to claim 1,
Each of the plurality of stages of controlled units further includes a three-state gate having a signal input unit, a signal output unit, and an enable input unit,
By connecting the signal output unit in the subsequent stage and the signal input unit in the previous stage by the data line, the three-state gates in the controlled units in the plurality of stages are connected in series,
In each of the plurality of stages of controlled units, one terminal of the parallel output terminal of the first serial / parallel conversion circuit is connected to the enable input unit,
When the control device reads data from the selected first control target, the control device makes the enable input unit connected to one terminal of the parallel output terminal non-enable by the first chip select data signal. By activating and setting the three-state gate to a high impedance output state, indefinite data on the data line located at a later stage than the controlled unit including the selected first control target is transferred to the control device. A serial communication control system that prevents it from reaching.

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