JP2000151748A - Device connection recognition method for communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device connection recognition method for a communication system which can recognize electric connection with a slave device at a master device without increasing a signal line. SOLUTION: This communication system performs communication by using each signal line for a bidirectional data signal, a clock signal and a scan signal for indicating that communication is being performed between a master device 1 and a slave device 2 which operates under management of the master device 1. In this communication system, the salve device 2 repeatedly transmits a specified pattern signal to the data signal line at least immediately after a power is supplied and the master device 1 decides whether or not a signal received through the data signal line is the specified pattern signal or not. When it is decided continuously more than the specified number of times that it is the specified pattern signal, it is recognized that the master device has electric connection with the slave device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system between a master device and a slave device, and more particularly to a method for recognizing an electrical connection of a slave device in the master device.

[0002]

2. Description of the Related Art As one of serial communication systems, there is a three-wire interface system. This three-wire interface system is a system for performing communication between devices using three signal lines corresponding to a bidirectional data signal, a scan signal indicating that communication is in progress, and a clock signal. It is applied to data transfer between a master device that manages processing and a slave device that operates under the control of the master device.

The three-wire interface system further includes a wait system and an ACK system. The wait method is a method of transferring data at a predetermined time, and has a data format as shown in FIG. In this data format, transmission from the master device to the slave device is performed in the order of R / W, address, and parity.
R / W is a bit indicating the distinction between writing and reading data. The address indicates the data write position of the slave device when writing, and indicates the data read position of the slave device when reading. After a predetermined wait period (WAIT) after transmission from the master device, the data is transferred from the master device to the slave device in the order of the data itself and the parity at the time of writing, and from the slave device to the master device at the time of reading. Data transfer is performed in the order of data body and parity. Note that the scan signal indicates, for example, “1” from the R / W to the last parity as being in communication.

The ACK method is a method of completing communication after waiting for an ACK as a response signal from a slave device. A
In the data format of the CK system, as shown in FIG.
At the time of reading, transmission from the master device to the slave device is performed in the order of R / W, address, and parity. In response, ACK, data body, and parity are transmitted from the slave device to the master device in the order of data. It is. R / W is the same as in the case of the weight method,
Is a fixed pattern such as "101".
At the time of writing, transmission from the master device to the slave device is performed in the order of R / W, address, parity, data body, and parity, while response transmission is performed from the slave device to the master device in the order of ACK and parity. It is. Since the scan signal is communicating from R / W to the last parity, the scan signal indicates, for example, "1".

When a master device and a slave device are individually formed as substrates and mounted on the same system by connector connection or the like, the master device is in a mounted state of the slave devices, that is, electrically connected to each other. It is necessary to check the status. When communication is performed between such a master device and a slave device by a three-wire interface method, a signal line for mounting recognition is provided between the master device and the slave device in order to recognize the mounting state on the master device side. It was provided in. When mounting is performed in the slave device, the level of this signal line is set to, for example, a high level, and in the master device, the mounting state of the slave device is determined from the level of the signal line.

[0006]

However, there is a problem that the number of pins of the connector is increased due to the signal line for mounting recognition, and the configuration of the communication system is complicated. Accordingly, an object of the present invention is to provide a device connection recognition method of a communication system in which a master device can recognize an electrical connection with a slave device without increasing the number of signal lines.

[0007]

According to the present invention, there is provided an apparatus connection recognition method for a communication system, comprising: a bidirectional data signal between a master device and a slave device operating under the control of the master device;
In a communication system for performing communication using a signal line corresponding to each of a clock signal and a scan signal indicating that communication is being performed, a method of recognizing an electrical connection with a slave device in a master device, comprising: The device repeatedly sends a predetermined pattern signal to the data signal line at least immediately after power-on, and the master device determines whether or not the signal received via the data signal line is a predetermined pattern signal, and Is determined to be electrically connected to the slave device when it is continuously determined that this is a predetermined number of times or more.

Further, the device connection recognizing method of the communication system according to the present invention indicates that a bidirectional data signal, a clock signal and communication are being performed between a master device and a slave device operating under the control of the master device. In a communication system in which communication is performed using a signal line corresponding to each of the scan signals, and a slave device transmits a response signal to the master device via a data signal line in response to a data signal from the master device, The master device stops transmitting a scan signal when a response signal cannot be received for a predetermined time or more after transmitting a data signal, and the slave device stops communication during transmission. When it detects that the scan signal can no longer be received at, it repeatedly sends a predetermined pattern signal to the data signal line, and the master device It is determined whether or not the signal received via the data signal line is a predetermined pattern signal, and when it is determined that the signal is the predetermined pattern signal, it is recognized that an electrical connection with the slave device is established. Features.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 3 shows a three-wire interface communication system between a master device and a slave device to which the method according to the present invention is applied. In this communication system, a master device 1 and a slave device 2 are individually formed on a substrate, and three signal lines 3 to 5 corresponding to a clock signal, a scan signal, and a data signal, respectively.
Are connected via a connector (not shown) for each substrate.

The master device 1 includes a transmission / reception control unit 11, a clock transmission unit 12, a scan transmission unit 13, and a data reception unit 14.
And a data transmission unit 15. Transmission / reception controller 11
Controls transmission and reception of data, transmission of a clock signal, and transmission of a scan signal of the master device 1. Clock sending unit 1
2 transmits a clock signal to the signal line 3 in response to a command from the transmission / reception control unit 11. The scan sending unit 13 sends a scan signal to the signal line 4 according to a command from the transmission / reception control unit 11. The data receiving unit 14 receives transmission data from the slave device 2 and supplies the data to the transmission / reception control unit 11. The data transmission unit 15 transmits data to be transmitted to the transmission / reception control unit 11.
And sends it out to the signal line 5.

The data receiving unit 14 includes a selector 16 for switching the output destination of the signal from the data signal line 5 and a pattern recognition unit 17 to which one output of the selector 16 is connected.
And a register 18 for holding a recognition result by the pattern recognition unit 17. The selector 16 is connected as an output destination to the transmission / reception control unit 11 in addition to the pattern recognition unit 17, and in response to a control signal S2 from the transmission / reception control unit 11, one of the pattern recognition unit 17 and the transmission / reception control unit 11 The output destination. Pattern recognition unit 1
Reference numeral 7 sets a register 1 to "1" when a predetermined pattern, for example, a signal "10" is continuously supplied N times. The output of the pattern recognition unit 17 is also connected to the transmission / reception control unit 11 and the scan transmission unit 13.

The slave device 2 includes a transmission / reception control unit 21, a clock reception unit 22, a scan reception unit 23, a data transmission unit 24, and a data reception unit 25. The transmission / reception control unit 21 controls data transmission / reception of the slave device 2. The clock receiving unit 22 receives the clock signal from the signal line 3 and supplies the clock signal to the transmission / reception control unit 21. Scan receiver 23
Receives the scan signal from the signal line 4 and supplies it to the transmission / reception control unit 21. The data transmission unit 24 obtains data to be transmitted from the transmission / reception control unit 21 and transmits the data to the signal line 5. The data receiving unit 25 receives transmission data from the master device 1 through the signal line 5 and supplies the data to the transmission / reception control unit 21.

The data transmission section 24 includes a pattern generation section 26 for generating the above-mentioned predetermined pattern, and a transmission / reception control section 21.
A selector 27 for selectively outputting one of the data signal from the scan signal generator and the output signal from the pattern generator 26 to the signal line 5 in accordance with the control signal S3 from the scan receiver 23.
And are provided. The scan receiver 23 generates a pattern output control signal S3 when a power supply (not shown) is turned on, and thereafter generates a pattern output stop control signal S3 when receiving a scan signal.

In the communication system having such a configuration, when the master device 1 is in an initial state such as immediately after power-on, the signal from the signal line 5 is subjected to pattern recognition by the selector 16 in accordance with the control signal S2 from the transmission / reception control unit 11. It is supplied to the section 17. However,
Even if the signal from the signal line 5 is supplied to the pattern recognition unit 17 by the selector 16, no signal is supplied to the pattern recognition unit 17 when the slave device 2 is not mounted in the system. Therefore, the content held in the register 18 is “0”, indicating that the slave device 2 is not mounted.

When the slave device 2 is mounted on the system, power is supplied to the slave device 2, so that the scan receiving section 23 generates a pattern output control signal S3, and the selector 27 responds to the pattern output control signal S3. The pattern signal generated by the pattern generation unit 26 is transmitted to the signal line 5.
Relay output. The pattern signal is supplied to the selector 16 of the master device 1 via the signal line 5, and the selector 16 supplies the pattern signal to the pattern recognition unit 17. In the pattern recognition section 17, the pattern signal is a predetermined pattern "10".
If so, the number of times is counted, and when a predetermined pattern "10" is obtained continuously N times, the mounting detection signal S1 indicating "1" is supplied to the register 18. Therefore, register 1
8 is “1”, indicating that the slave device 2 is mounted and is electrically connected to the master device 1.

The mounting detection signal S 1 indicating “1” generated from the pattern recognition unit 17 is supplied to the transmission / reception control unit 11 and the scan transmission unit 13. The transmission / reception control unit 11 supplies the switching control signal S2 to the selector 16 in response to the mounting detection signal S1, whereby the selector 16 relays and supplies the reception data from the signal line 5 to the transmission / reception control unit 11. On the other hand, the scan sending unit 13 outputs the mounting detection signal S1.
, The scan signal is output to the signal line 4 for one clock. The scan signal for one clock is applied to signal line 4
Is received by the scan receiving unit 23, the scan receiving unit 23 generates a pattern output stop control signal S3 to the selector 27, and outputs the pattern output stop control signal S3.
In response to 3, the selector 27 performs a switching operation to output the output signal of the transmission / reception control unit 21 to the signal line 5 instead of the output pattern signal of the pattern generation unit 26. Therefore, the master device 1 can confirm the mounting of the slave device 2, and thereafter, data communication between the master device 1 and the slave device 2 becomes possible.

As described above, in the above embodiment,
The slave device repeatedly sends a predetermined pattern signal to the data signal line at least immediately after power-on, and the master device determines whether or not the signal received via the data signal line is a predetermined pattern signal, and When it is determined that the signal is a signal for a predetermined number of times or more, it is recognized that the slave device is electrically connected to the slave device. Therefore, the master device and the slave device are connected to the slave device only by the original three signal lines. Can be confirmed by the master device.

In the above-described embodiment, the selector 2 outputs the pattern signal until the pattern output stop control signal S3 is supplied from the scan receiving unit 23. However, the selector 2 outputs the pattern signal for a predetermined time after the power is supplied to the slave device 2. Only the pattern signal may be output via the selector 27. Further, in the above-described embodiment, the configuration in which communication is performed by the weight method has been described, but the present invention can be similarly applied to the case of the ACK method.

Further, in the above-described embodiment, the pattern signal is generated immediately after the board constituting the slave device 2 is mounted on the system and the power is turned on, but the communication thereafter is performed. A pattern signal may be generated from the slave device 2 in a non-period period (a period in which a scan signal is not generated), and the master device 1 may perform pattern recognition.

FIG. 4 also shows an embodiment of the present invention. In the communication system shown in FIG. 4, the ACK method of the three-wire interface method is applied. The same parts as those of the system shown in FIG. 3 are denoted by the same reference numerals. ACK is sent to the transmission / reception controller 11 of the master device 1.
An ACK recognition unit 31 for recognizing (response signal) is built in. The switching control signal S5 is supplied from the ACK recognition unit 31 to the selector 16.

The transmission / reception control unit 21 of the slave device 2 has A
An ACK generation unit 32 for generating a CK is included. Further, the selector 27 of the slave device 2 is
The switching operation is performed by a control signal from the controller. In place of the pattern generation unit 26 shown in FIG. 3, a pattern generation unit 33 that generates a pattern signal indicating “0” at, for example, a predetermined cycle is provided. Similarly, the pattern recognition unit 34 that recognizes a pattern signal indicating “0” instead of the pattern recognition unit 17 illustrated in FIG. The unit 14 is provided. The output of the pattern recognition unit 34 is connected to the register 18, but is not connected to the scan sending unit 13. Other configurations are the same as those of the communication system of FIG.

In the communication system having such a configuration, during communication with the slave device 2, the master device 1 waits for an ACK from the slave device 2 after transmitting parity as in the data format shown in FIG. At this time, A
In response to the switching control signal S5 from the CK recognition unit 31, the selector 16 transmits a signal from the signal line 5 to the ACK of the transmission / reception control unit 11.
The information is relayed to the recognition unit 31. After the transmission from master device 1, ACK recognizing section 31 performs A
If CK cannot be recognized, the transmission / reception control unit 11 causes the scan transmission unit 13 to stop transmitting the scan signal, and terminates communication with the slave device 2. At the end of this communication, the selector 16 enters a state of relaying the signal from the signal line 5 to the pattern recognition unit 34 in response to the switching control signal S5.

The transmission / reception control unit 21 of the slave device 2 generates a pattern output control signal S6 when the scan reception unit 23 detects that the scan signal is no longer received before the communication is completely completed. Then, in response to the pattern output control signal S 6, the selector 27 relays and outputs the pattern signal indicating “0” generated by the pattern generation unit 33 to the signal line 5. The pattern signal is supplied to the selector 16 of the master device 1 via the signal line 5, and the selector 16 supplies the pattern signal to the pattern recognition unit 34. When the pattern recognition unit 34 recognizes that the pattern signal is a predetermined pattern “0”, “1” is held in the register 18 accordingly. Therefore, register 1
8 is “1”, indicating that the slave device 2 is mounted.

The transmission / reception control unit 11 of the master device 1 determines that the second predetermined time has elapsed after the stop of the transmission of the scan signal.
The switching control signal S2 is supplied to the selector 16, whereby the selector 16 enters a state in which the data received from the signal line 5 is relayed to the transmission / reception control unit 11. As described above, in the above embodiment, after transmitting the data signal, the master device stops transmitting the scan signal when ACK cannot be received for a predetermined time or more, and the slave device receives the scan signal during communication. When it is detected that the signal cannot be transmitted, a predetermined pattern signal is repeatedly transmitted to the data signal line, and the master device determines whether or not the signal received via the data signal line is a predetermined pattern signal, and When it is determined that the signal is a signal, the master device recognizes that it is electrically connected to the slave device, so that the master device can determine whether the slave device is not mounted or an error occurred during communication.

[0025]

As described above, according to the present invention, the master device can recognize the electrical connection with the slave device without increasing the number of signal lines between the master device and the slave device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a data format of a weight system.

FIG. 2 is a diagram showing a data format of an ACK scheme.

FIG. 3 is a block diagram showing an embodiment of the present invention.

FIG. 4 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master device 2 Slave device 3-5 Signal line 11, 21 Transmission / reception control part 12 Clock transmission part 13 Scan transmission part 14, 25 Data reception part 15, 24 Data transmission part 22 Clock reception part 23 Scan reception part

Claims (3)

[Claims] 1. A signal line corresponding to each of a bidirectional data signal, a clock signal, and a scan signal indicating that communication is in progress between a master device and a slave device operating under the control of the master device. In the communication system, the master device recognizes an electrical connection with the slave device, wherein the slave device repeatedly transmits a predetermined pattern signal to a data signal line at least immediately after power-on. The master device determines whether the signal received via the data signal line is the predetermined pattern signal, and when determining that the signal is the predetermined pattern signal continuously for a predetermined number of times or more, A method for recognizing device connection of a communication system, comprising recognizing that an electrical connection is established with a slave device. 2. The master device transmits the scan signal to the slave device for a predetermined clock when the master device determines that the signal is the predetermined pattern signal a predetermined number of times or more. 2. The apparatus connection recognition method for a communication system according to claim 1, wherein the transmission of the predetermined pattern signal is stopped in accordance with the scan signal for a minute. 3. A signal line corresponding to each of a bidirectional data signal, a clock signal, and a scan signal indicating that communication is in progress between a master device and a slave device operating under the control of the master device. In the communication system in which the slave device transmits a response signal to the data signal from the master device via the data signal line to the master device, the master device communicates with the slave device. A method for recognizing an electrical connection, wherein after transmitting a data signal, the master device stops transmitting the scan signal when the response signal cannot be received for a predetermined time or more, and the slave device is in the middle of communication. When it is detected that the scan signal can no longer be received, a predetermined pattern signal is repeatedly transmitted to the data signal line; The data device determines whether or not the signal received via the data signal line is the predetermined pattern signal, and when determining that the signal is the predetermined pattern signal, does not establish an electrical connection with the slave device. A device connection recognition method for a communication system, comprising: