JPH04129440A - Communication equipment - Google Patents

Abstract

PURPOSE:To prevent the leakage of secret information such as a password by connecting a transmission serial clock generating circuit and a reception serial clock generating circuit to a transmission circuit and a reception circuit respectively. CONSTITUTION:The communication equipment consists of a transmission circuit 1, a reception circuit 2, a transmission serial clock generating circuit 3 connecting to the transmission circuit 1, a reception serial clock generating circuit 4 connecting to the reception circuit 2 and a bus 5, a transmission use reference clock input terminal TXCK, a reception reference clock input terminal RXCK, a transmission data output terminal TXD and a reception data input terminal RXD. Since the communication is implemented by using a serial clock of a communication format understood by the sender side and the receiver side only, even when the other 3rd party connects the communication equipment to the data line, the content of the communication data cannot be read. Thus, the leakage of secret information such as a password is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication device, and particularly to a communication device that communicates serial data.

[Conventional technology]

Conventionally, a start-stop synchronization type communication device is known as a communication device that performs such serial data communication.

FIG. 4 is a block diagram of an example of such a conventional start-stop cyclic communication device.

As shown in FIG. 4, the conventional communication device is composed of a transmitting circuit 1, a receiving circuit 2, and a bus router for transmitting and receiving data Do-Dn, and also includes a serial clock input terminal TXFCK for transmitting and a serial clock input terminal for receiving. Input terminal RX
It has SCK, a transmission data output terminal TXD, and a reception data input terminal RXD. Further, a transmission data write signal TXWR is input to the transmission circuit 1, and a transmission data write signal TXWR is input to the reception circuit 2.
The received data readout RXRD is input to.

5 and 6 are waveform diagrams for explaining the transmission operation and reception operation of the communication device in FIG. 4, respectively.

As shown in FIG. 5, in the data transmission operation, data Do to Da written in the transmission circuit 1 by the transmission data write signal TXWR is transmitted from the transmission data output terminal TXD in synchronization with the transmission serial clock TXSCK. At this time, the cycles of each bit output from the output terminal TXD are synchronized with the serial clock TXSCK, so they are equally spaced.

Further, as shown in FIG. 6, the data reception operation is started when the reception circuit 2 detects the falling edge of the start bit of the input from the reception data input terminal RXD. Received synchronously.

That is, according to the received data read signal RXRD,
The received data DO to Db are read out. In this case as well, the cycles of each bit received from the input terminal RXD are synchronized with the serial clock RXSCK, so they are equally spaced.

As described above, conventional communication devices transmit and receive data in synchronization with a serial clock that is emitted at regular intervals.

[Problem to be solved by the invention]

The conventional communication devices described above transmit and receive data using a serial clock with a fixed cycle, so if another third party connects the communication device to the data line, it is possible to easily read and receive the contents of the communication data on the data line. The disadvantage is that it can be read and confidential information such as passwords may be leaked.

An object of the present invention is to provide a communication device that can prevent leakage of confidential information such as passwords.

[Means to solve the problem]

A communication device of the present invention includes a transmitting circuit and a receiving circuit connected to a data bus, and a transmitting serial clock generator connected to the transmitting circuit and generating a transmitting serial clock at an arbitrary period with respect to a reference clock for each bit of data. A receiving serial clock generating circuit is connected to the receiving circuit and generates a receiving serial clock at an arbitrary period with respect to a reference clock for each bit of data.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a communication device showing one embodiment of the present invention.

As shown in FIG. 1, this embodiment includes a transmitting circuit 1, a receiving circuit 2, a transmitting serial clock generating circuit 3 connected to the transmitting circuit 1, and a receiving serial clock generating circuit 4 connected to the receiving circuit 2. It also has a reference clock input terminal TXCK for transmission, a reference clock input terminal RXCK for reception, a transmission data output terminal TXD, and a reception data input terminal RXD. Further, the transmission serial clock generation circuit 3 sends out a transmission serial clock TXSCK to the transmission circuit 1, while the reception serial clock generation circuit 4 sends out a reception serial clock RXSCK to the reception circuit 2. Note that the transmission data write signal TXWR to the transmission circuit 1 and the reception data read signal RXRD are the same as in the conventional example.

2 and 3 are waveform diagrams for explaining the transmission operation and reception operation of the communication device in FIG. 1, respectively.

As shown in FIG. 2, in the data transmission operation, first, a communication format is determined for each bit of the transmission data to be transmitted with the receiving side. For example, in this example, the start bit is set to 2 reference clocks, the data beat O is set to 4 reference clocks, bit 1 is set to 1 reference clock, and bits 2 and 3 are set to 2 reference clocks.

Next, transmit data write signal TXWR to transmit circuit 1
The data DO to Da written to the transmitting circuit 1 are synchronized from the transmitting reference clock TXCK to the transmitting serial clock TXSCK generated by the transmitting serial clock generating circuit 3 based on the communication format, and are output from the transmitting data output terminal TXD. Sent.

Further, as shown in FIG. 3, the communication format for the data reception operation is determined in the same way as for the data transmission operation. First, reception is started by the reception circuit 2 detecting the falling edge of the start bit input from the reception data input terminal RXD. Next, the reception reference clock RX
Based on the communication format from CK, the reception serial clock generation circuit 4 generates a reception serial clock RXSCK. The receiving circuit 2 receives data in synchronization with this receiving serial clock RXSCK. Further, in response to the reception data readout signal RXRD, the receiving circuit 2 reads out the received data via the bus 5 as in data sampling A.

As a result, the contents of the data sent and received on the data line are communicated in synchronization with the serial clock in a communication format known only to the sending and receiving sides, so that other Even if a third party connects a communication device to the data line, the contents of the communication data cannot be read out.

〔Effect of the invention〕

As explained above, in the communication device of the present invention, by connecting the transmitting serial clock generating circuit and the receiving serial clock generating circuit to the transmitting circuit and the receiving circuit, respectively, the contents of the transmitted and received data on the data line can be changed between the transmitting side and the receiving side. Since it is possible to communicate using a serial clock in a communication format that is understood only by the user, even if another third party connects a communication device to the data line, the contents of the communication data cannot be read, and confidential information such as passwords can be stored. It has the effect of being able to prevent leakage 6

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a communication device showing an embodiment of the present invention, and FIGS. 2 and 3 are waveform diagrams for explaining the transmission operation and reception operation of the communication device in FIG. 1, respectively.
FIG. 4 is a block diagram of a communication device showing an example of the conventional technology, and FIG.
6 are waveform diagrams for explaining the transmitting operation and receiving operation of the communication device in FIG. 4, respectively. DESCRIPTION OF SYMBOLS 1... Transmission circuit, 2... Receiving circuit, 3... Serial clock generation circuit for transmission, 4... Serial tarlock generation circuit for reception, 5... Bus (Do to Dn), TXC
K... Reference clock input terminal for transmission, RXCK...
Reception reference clock input terminal, TXSCK...transmission serial clock, RXSCK...reception serial clock, TXD...transmission data output terminal, RXD...
- Reception data input terminal, TXWR...transmission data write signal, RXRD...reception data read signal.

Claims (1)

[Claims] a transmitting circuit and a receiving circuit connected to the data bus; a transmitting serial clock generating circuit connected to the transmitting circuit and generating a transmitting serial clock at an arbitrary period with respect to a reference clock for each bit of data; 1. A communication device comprising: a reception serial clock generation circuit which is connected and generates a reception serial clock at an arbitrary period with respect to a reference clock for each bit of data.