JPH0571978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a data transmission system for transferring data from a microcomputer to another microcomputer.

Conventional technology Generally, when data is transferred from a first microcomputer to a second microcomputer, a line for clock transmission and a line for data transmission are provided, and a The data is sent to the second microcomputer, and the second microcomputer reads the data at the timing of the sent clock.

Problems to be Solved by the Invention In the conventional method described above, when the second microcomputer is in a state where it cannot accept data sent from the first microcomputer, for example, when it is performing another task or When there is a power outage, etc., the first microcomputer only sends out data unilaterally, resulting in the inconvenience that the data is not transmitted to the second microcomputer. Such problems tend to occur when data is transferred only once or when a small-scale second microcomputer is used.

Means for Solving the Problems The present invention provides a data transmission system in which data is transferred from a first microcomputer to a second microcomputer, in which a start signal is sent from the first microcomputer to the second microcomputer. When the second microcomputer detects the start signal, it sequentially sends a large number of clocks that are continuously generated from the second microcomputer to the first microcomputer, and the first microcomputer By sequentially detecting the multiple clocks from the second microcomputer, a large amount of data is sequentially sent to the second microcomputer, and the second microcomputer detects the first clock using the multiple clocks. It is configured to sequentially read the above-mentioned large amount of data from the microcomputer.

Function: Since the two microcomputers mutually confirm that data is being sent and received, data can be transferred reliably, and especially if an abnormality occurs in the continuous clock generation from the second microcontroller. When this clock is no longer sent sequentially from the second microcomputer to the first microcomputer, data will be sent sequentially from the first microcomputer to the second microcomputer from that point on, even if data is being transferred sequentially. Therefore, the data can be transferred more reliably with a simple configuration.

Embodiment As shown in FIGS. 1 and 2, when data is sent from the first microcomputer A to the second microcomputer B,
First, at timing _t1 in FIG. 2, a start bit falling from "H" to "L" is sent from A to B to notify the start of data transfer. Through this, B learns that the transfer has started, and then sends a clock to A at timing _t2 . When the clock returns after outputting the start bit, A determines that B has learned that the transfer has started, and immediately sends out the first data, for example "H". After B reads this data "H" at timing _t3 , it subsequently sends the next clock to A at timing _t4 . Thereafter, by repeating data sending, reading, and clock sending at timings t ₅ , t ₆ , etc., one data block is converted to A.
can be transferred from to B without error.

If A sends a start bit while B is in a state where it cannot accept data, and then B starts moving, B will not be able to detect the start bit. On the other hand, no matter how long A waits, the clock does not return, so the line stops forever. As a countermeasure against this problem, if A does not return the clock even after a predetermined period of time has elapsed after issuing the start bit, A will issue the start bit again.

When the transfer of one data block is completed, check the level of the power supply battery of A. If it is found that the voltage of the battery did not reach the specified level during the transfer, the reliability of the data may be low. As a result, all data transferred at that time may be invalidated.

Effects of the invention Since the two microcomputers A and B perform the transfer work while constantly confirming that data is being sent and received, all data can be reliably transferred without errors. If an abnormality occurs in the generation of the clock that occurs during a period of time, and this clock is no longer sent sequentially from the second microcontroller to the first microcontroller, even if the data is being transferred sequentially, from that point on, the data will not be sent to the first microcontroller. Since data is no longer sent sequentially from one microcomputer to a second microcomputer, the data can be transferred more reliably with a simple configuration. The present invention is particularly effective for use in systems where data transfer is performed only once.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a timing chart. Note that in the symbols used in the drawings, A: the first microcomputer, and B: the second microcomputer.

Claims (1)

[Claims] 1. In a data transmission method in which data is transferred from a first microcomputer to a second microcomputer, when a start signal is sent from the first microcomputer to the second microcomputer, the By detecting the start signal, the second microcomputer
The second microcomputer sequentially sends a large number of clocks generated continuously to the first microcomputer, and the first microcomputer sequentially detects the large number of clocks from the second microcomputer. The data is sequentially sent to the second microcomputer, and the second microcomputer is configured to sequentially read the large number of data from the first microcomputer using the large number of clocks. Transmission method.