JPH0567013A - Dma serial receiving operation end system - Google Patents

Abstract

PURPOSE:To improve a processing speed by omitting a useless time for judging the end of a DMA reception. CONSTITUTION:At the time of operating a start-stop synchronizing serial data communication between a host computer and a lower controller by a DMA operation, the lower controller is equipped with a detector which detects a preliminarily set transfer end code. When the transfer end code is detected by the detector during the serial data, an interrupting operation is generated at the lower controller, so that the DMA operation can be forcedly ended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a termination method in the case where a control device having an asynchronous synchronous serial data communication function, for example, an NC control device receives asynchronous synchronous serial data from a host computer by a DMA operation.

[0002]

2. Description of the Related Art When receiving asynchronous serial data by a DMA operation, if the amount of data received by a partner device is not known in advance, it is necessary to detect the end of reception by some means. Conventionally, the change of the DMA reception counter is checked by the periodic check by the timer interruption,
If there is no change within a certain period, it is considered that the reception has ended.

[0003]

However, in the above-mentioned conventional example, it takes a certain amount of time for determination until the end of reception is detected, and the interruption of the temporary transfer due to the convenience of the partner device is also judged as the end of reception. There was a problem. On the other hand, in Japanese Patent Application Laid-Open No. 61-241858, there is also one that sends a signal indicating the end by a signal line different from the data signal line, but there is a drawback in that the number of signal lines increases. Therefore, an object of the present invention is to provide a method capable of detecting the end of reception by the received data itself and immediately ending the DMA operation.

[0004]

In order to achieve the above object, the present invention has the following constitution. That is,
A reception end code detector composed of a comparison circuit of an arbitrary reception end code setting register and a reception data register is provided, and an interrupt signal is output to the NC control device when data matches, thereby forcibly stopping the DMA reception operation. is there.

[0005]

Therefore, by detecting the preset reception end code, the DMA reception operation can be immediately terminated, so that a high-speed response to reception can be realized. Further, since an arbitrary code can be set as the reception end code, for example, the reception end code is 8 bits (1
With (byte) data, it is possible to limit the type of transfer data to only 1 byte.

[0006]

1 is a block diagram showing an embodiment of the present invention. The arbitrary end code set in the reception end code setting register 1 in the figure and the data received by the serial receiver 2 are compared by the comparator 3, and when both are matched, DM
The A reception end interrupt signal 7 is output to the CPU 4. C
The PU 4 immediately starts the interrupt process, ends the reception operation of the DMA controller 5, and processes the reception data written in the RAM 6.

[0007]

As described above, according to the present invention, the reception data processing can be started immediately by the reception of the end code, so that the dead time for the reception end judgment which has been conventionally performed can be saved and the processing speed can be reduced. Can be improved. Further, since the termination judgment is made by the preset reception termination code, it is not necessary to reconfirm the certainty of the judgment.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of this configuration.

[Explanation of symbols]

 1 reception end code setting register 2 serial receiver 3 comparator 4 CPU 5 DMA controller 6 RMA 7 DMA reception end interrupt signal

Claims (1)

[Claims] 1. When a start-stop synchronous serial data communication is performed by a DMA operation between a high-order computer and a low-order control device, a detector for detecting a preset transfer end code is provided on the low-order control device side, and this detector is provided. A DMA serial reception operation ending method characterized in that, when the transfer end code is detected in serial data, an interrupt operation is generated in the lower controller to forcibly end the DMA operation.