JPH0897809A - Bidirectional digital communication equipment and bidirectional digital communication system - Google Patents

Abstract

PURPOSE: To correctly sample reception data in synchronism with synchronization timing signals even when a communication distance is long and a communication speed is fast. CONSTITUTION: A first digital communication equipment 1 transmits the synchronization timing signals TOI along with data DO11-D01n at the time of transmission, receives the transmitted data DI11-DI1n and synchronization timing signals TI1 at the time of reception and samples the data DI11-DI1n in synchronism with the synchronization timing signals TI1. A second digital communication equipment 2 transmits the synchronization timing signals TO2 along with the data DO21-DO2n at the time of the transmission, receives the transmitted data DI21-DI2n and synchronization timing signals TI2 at the time of the reception and samples the data DI21-DI2n in synchronism with the synchronization timing signals TI2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional digital communication device and a bidirectional digital communication system.

[0002]

2. Description of the Related Art Generally, in synchronous communication, a synchronous timing signal composed of, for example, a stationary rectangular wave is used to determine the timing of sampling data.

When transmitting data from the master station to the slave station, as shown in FIG. 4, the master station transmits the data and the synchronization timing signal to the slave station. The slave station samples the received data in synchronization with the falling edge of the received synchronization timing signal.

On the contrary, when transmitting data from the slave station to the master station, first, as shown in FIG. 5, only the synchronization timing signal is transmitted from the master station to the slave station. The slave station transmits data to the master station in synchronization with the received synchronization timing signal. The master station samples the data sent from the slave station in synchronization with the falling edge of its own synchronization timing signal.

As described above, conventionally, the master station transmits the synchronization timing signal to the slave station, and both the master station and the slave station sample data in synchronization with the synchronization timing signal.

[0006]

However, when the distance between the master station and the slave stations is relatively long, a delay occurs while the synchronization timing signal and the data are transmitted through the transmission path.

For example, when transmitting data from a master station to a slave station as shown in FIG. 4, both the synchronization timing signal and the data are delayed by a time DL. On the other hand, as shown in FIG. 5, when transmitting data from the slave station to the master station, a delay of time DL occurs while the synchronization timing signal is transmitted from the master station to the slave station, and the slave station transmits data to the master station. , A delay of time DL occurs. Since the data is transmitted in synchronization with the delayed synchronization timing signal, the data received by the main station is delayed from the synchronization timing signal of the main station by twice the time DL.

In particular, when the communication speed is high, the main station has a large gap between its own synchronization timing signal and the received data, so that the data cannot be read in synchronization with the synchronization timing signal. In the example of FIG. 5, the main station has a time difference of 2DL between the synchronization timing signal of itself and the received data, and the data cannot be sampled in synchronization with the fall of the synchronization timing signal. Therefore, there is a problem that long-distance communication and high-speed communication cannot be performed.

An object of the present invention is to provide a bidirectional digital communication device capable of accurately sampling data in synchronization with a synchronization timing signal even when the communication distance is long and the communication speed is high.

Another object of the present invention is to provide a bidirectional digital communication system capable of accurately sampling data in synchronization with a synchronization timing signal even when the communication distance is long and the communication speed is high.

[0011]

[Means for Solving the Problems]

(1) First invention A bidirectional digital communication device according to a first invention is a transmitting means for transmitting a sync timing signal together with data at the time of transmission, and a sync timing signal received together with data at the time of reception, and the received sync timing signal. And a receiving means for sampling data in synchronization with.

(2) Second Invention A bidirectional digital communication system according to a second invention is a bidirectional digital communication system including a plurality of digital communication devices, wherein each of the plurality of digital communication devices transmits data together with data. The present invention is characterized by including a transmitting means for transmitting the synchronization timing signal and a receiving means for receiving the synchronization timing signal together with the data at the time of reception and sampling the data in synchronization with the received synchronization timing signal.

[0013]

In the bidirectional digital communication device according to the first aspect of the present invention, when transmitting, a synchronous timing signal is transmitted together with the data, and when receiving, the transmitted data and the synchronous timing signal are received. There is no deviation from the signal. Therefore, even when the communication distance is long and the communication speed is fast, the data can be accurately sampled in synchronization with the synchronization timing signal.

In the bidirectional digital communication system according to the second aspect of the present invention, the digital communication device on the transmission side transmits the synchronization timing signal together with the data, and the digital communication device on the reception side transmits the data and the synchronization timing. Since the signal is received, the data does not deviate from the synchronization timing signal in the receiving side digital communication device. Therefore, even when the distance between the digital communication device on the transmitting side and the digital communication device on the receiving side is long and the communication speed is high, the digital communication device on the receiving side accurately samples data in synchronization with the synchronization timing signal. be able to.

[0015]

1 is a circuit diagram showing the configuration of a main part of a bidirectional digital communication system including a digital communication device according to an embodiment of the present invention. FIG. 1 shows only the transmitting circuit and the receiving circuit of the first digital communication device 1 serving as the master station and the second digital communication device 2 serving as the slave station.

In FIG. 1, a first digital communication device 1
Includes n output buffers 11 to 1n for outputting n-bit data, an input buffer 12 for inputting a synchronization timing signal, an output buffer 13 for outputting a synchronization timing signal, and a pull-down resistor 14.

On the other hand, the second digital communication device 2 similarly has n output buffers 21 to 2n for outputting n-bit data, an input buffer 22 for inputting a synchronization timing signal, and a synchronization timing signal. An output buffer 23 and a pull-down resistor 24 for outputting

The transmission line 3 includes n transmission lines 31 to 3n for bidirectionally transmitting n-bit data and a transmission line 30 for bidirectionally transmitting a synchronization timing signal. In the first digital communication device 1, the transmitting signal S1 becomes active (for example, high level) during transmission,
The output buffers 11 to 1n and 13 are turned on. As a result, the data DO11 to DO1n are transferred to the output buffer 11
Is output to the input / output terminals T11 to T1n via
The synchronization timing signal TO1 is output to the input / output terminal T12 via the output buffer 13. Data DO11 to DO
1n is transmitted to the second digital communication device 2 via the transmission lines 31 to 3n, and the synchronization timing signal TO1 is transmitted to the transmission line 3
It is transmitted to the second digital communication device 2 via 0.

During reception, the in-transmission signal S1 becomes inactive (for example, low level), and the output buffers 11 to 1
n and 13 are turned off. In this case, the data DI11 to DI1n transmitted from the second digital communication device 2 via the transmission lines 31 to 3n are input / output terminals T11 to T.
1n, and the synchronization timing signal TI transmitted from the second digital communication device 2 via the transmission line 30.
1 is input via the input / output terminal T12 and the input buffer 12. The data DI11 to DI1n are sampled in synchronization with the synchronization timing signal TI1.

On the other hand, in the second digital communication device,
During transmission, the in-transmission signal S2 becomes active (for example, high level), and the output buffers 21 to 2n and 23 become conductive. As a result, the data DO21 to DO2n are transferred to the input / output terminals T21 to T2 via the output buffers 21 to 2n.
The sync timing signal TO2 is output to the input / output terminal T22 via the output buffer 23. The data DO21 to DO2n are transmitted to the first digital communication device 1 via the transmission lines 31 to 3n, and the synchronization timing signal T
O2 is transmitted to the first digital communication device 1 via the transmission line 30.

During reception, the in-transmission signal S2 becomes inactive (for example, low level) and the output buffers 21-2
n and 23 become non-conductive. As a result, the data DI21 to DI2n transmitted from the first digital communication device 1 via the transmission lines 31 to 3n are transferred to the input / output terminals T21 to T21.
The synchronization timing signal T input from T2n and transmitted from the first digital communication device 1 through the transmission line 30.
I2 is input via the input / output terminal T22 and the input buffer 22. The data DI21 to DI2n are sampled in synchronization with the synchronization timing signal TI2.

Next, an example of the operation in the case of transmitting data from the first digital communication device 1 serving as the master station to the second digital communication device 2 serving as the slave station will be described with reference to the timing chart of FIG. . In FIG. 2, transmission data DO11 to DO1n and reception data DI21 to DI2.
Of n, only 1-bit transmission data DO11 and 1-bit reception data DI21 are shown.

In the first digital communication device 1, the transmitting signal S1 is activated (high level). As a result, the first digital communication device 1 enters the transmission state, transmits the synchronization timing signal TO1, and transmits the data DO11 in synchronization with the synchronization timing signal TO1. In the example of FIG. 2, the data DO11 is transmitted in synchronization with the falling edge of the synchronization timing signal TO1.

In the second digital communication device 2, the in-transmission signal S2 becomes inactive (low level). As a result, the second digital communication device 2 is in the receiving state,
The synchronization timing signal TI2 and the data DI21 sent from the first digital communication device 1 are received. The data DI21 is sampled in synchronization with the falling edge of the synchronization timing signal TI2.

In this case, the synchronization timing signal TI2 and the data DI21 received by the second digital communication apparatus 2 are both time DL with respect to the synchronization timing signal TO1 and the data DO11 transmitted from the first digital communication apparatus 1. It's delayed. Therefore, the data DI
21 does not deviate from the synchronization timing signal TI2.

Next, an example of the operation when data is transmitted from the second digital communication device 2 which is a slave station to the first digital communication device 1 which is a master station will be described with reference to the timing chart of FIG. To do. Also in FIG. 3, transmission data DO21 to DO2n and reception data DI11 to DI
Of 1n, only 1-bit transmission data DO21 and 1-bit reception data DI11 are shown.

In the second digital communication device 2, the transmitting signal S2 becomes active (high level). As a result, the second digital communication device 2 enters the transmission state, transmits the synchronization timing signal TO2, and transmits the data DO21 in synchronization with the synchronization timing signal TO2. In the example of FIG. 3, the data DO21 is transmitted in synchronization with the falling edge of the synchronization timing signal TO2.

In the first digital communication device 1, the transmitting signal S1 becomes inactive (low level). As a result, the first digital communication device 1 is in the receiving state,
The synchronization timing signal TI1 and the data DI11 sent from the second digital communication device 2 are received. The data DI11 is sampled in synchronization with the falling edge of the synchronization timing signal TI1.

Also in this case, the first digital communication device 1
The synchronization timing signal TI1 and the data DI11 received at are the synchronization timing signal TO2 and the data DO2 transmitted at the second digital communication device 2.
Both of them are delayed by time DL. Therefore, the data DI11 does not deviate from the synchronization timing signal TI1.

As described above, in the bidirectional digital communication system of this embodiment, since the synchronization timing signal is always transmitted from the transmitting side to the receiving side together with the data, the data received at the receiving side may deviate from the synchronizing timing signal. There is no. Therefore, even when the communication distance between the transmission side and the reception side is long and the communication speed is high, the data can be accurately sampled on the reception side in synchronization with the synchronization timing signal.

In the above embodiment, the case where the present invention is applied to the digital communication device and the digital communication system for communicating the parallel data has been described. However, the present invention is the digital communication device and the digital communication system for performing the synchronous serial communication. Can be similarly applied to. In this case, the number of transmission lines for transmitting data is one.

The present invention can be applied to, for example, communication between a CPU and a peripheral device, communication between a CPU and a peripheral IC, and any other bidirectional digital communication system.

[0033]

According to the first aspect of the invention, even when the communication distance is long and the communication speed is fast, the received data does not deviate from the synchronization timing signal, and the received data is accurately sampled in synchronization with the synchronization timing signal. A two-way digital communication device capable of Therefore, long-distance communication and high-speed communication are possible.

According to the second aspect of the invention, even when the communication distance is long and the communication speed is high, the data does not deviate from the synchronization timing signal on the receiving side, and the reception data is sampled accurately in synchronization with the synchronization timing signal. A two-way digital communication system is obtained. Therefore, long-distance communication and high-speed communication are possible.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a main part of a bidirectional digital communication system including a digital communication device according to an embodiment of the present invention.

FIG. 2 is a timing chart showing an example of an operation when data is transmitted from a first digital communication device to a second digital communication device.

FIG. 3 is a timing chart showing an example of an operation when data is transmitted from the second digital communication device to the first digital communication device.

FIG. 4 is a timing chart showing an example of an operation when transmitting data from a master station to a slave station in a conventional bidirectional digital communication system.

FIG. 5 is a timing chart showing an example of an operation when transmitting data from a slave station to a master station in a conventional two-way digital communication system.

[Explanation of symbols]

 1 1st digital communication apparatus 2 2nd digital communication apparatus 3 Transmission path 11-1n, 13, 21-2n, 23 Output buffer 12,22 Input buffer 30, 31-3n Transmission line

Claims (2)

[Claims] 1. Transmitting means for transmitting a synchronization timing signal together with data at the time of transmission, and receiving a synchronization timing signal together with data at the time of reception,
A bidirectional digital communication device comprising: a receiving unit that samples data in synchronization with a received synchronization timing signal. 2. A bidirectional digital communication system including a plurality of digital communication devices, wherein each of the plurality of digital communication devices transmits a synchronization timing signal together with data at the time of transmission, and a synchronization timing signal together with data at the time of reception. Received
A two-way digital communication system comprising: a receiving unit that samples data in synchronization with a received synchronization timing signal.