JP2710706B2 - Data receiving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data receiving method in a synchronous transmission / reception protocol (shake hand).

[0002]

2. Description of the Related Art Conventionally, a synchronous transmission / reception protocol has been provided for performing transmission / reception while synchronizing between a device for transmitting data and a device for receiving the data. In the synchronous transmission / reception protocol, data is received by a data reception method described later.

In other words, a plurality of signal lines are provided for transmitting and receiving data using a synchronous transmission / reception protocol. As the signal lines, those controlled by the transmission side include a data line and a transmission completion line, and those controlled by the reception side include a reception completion line and a transmission hold request line. After setting the data on the data line, the transmitting side sets a transmission completion signal indicating that the transmission has been completed on the transmission completion line. The receiving side
The transmission completion signal is detected, the data is read, and when the reception is completed, a reception completion signal indicating that the reception is completed is set in the reception completion line. After confirming that the reception has been completed, the transmitting side sets the data and proceeds with each other.

[0004] The processing method after data reception on the receiving side is roughly divided into two methods. One is a case where the internal processing for processing the received data and the reception are not synchronized. In this case, for example, a reception buffer, a reception buffer head pointer, a reception buffer end pointer, A reception data storage pointer and a reception data read pointer are provided, and the writing and reading of data to and from the reception buffer are controlled using these pointers. The received data is stored in the buffer address indicated by the received data storage pointer asynchronously with the internal processing. The internal processing fetches data from the buffer address indicated by the received data read pointer and performs the processing independently, asynchronously with the reception.

The other is a case where internal processing and reception can be synchronized. In this case, no reception buffer is provided, the data is immediately processed internally after data reception, and data reception is performed again after the completion. . In any case, when trying to capture transmission data in a receivable state, if the data has not been transmitted yet, it is common to perform processing such as monitoring the state of the device unrelated to the internal processing of the data. .

When it is desired to process received data internally as fast as possible, a method having a reception buffer is:
Processing time is required for controlling the storage pointer and the read pointer, managing the buffer overflow, and the like, and this becomes an overhead. Therefore, a method having no reception buffer is selected. FIG. 4 is a flowchart showing a data reception process in a conventional data reception method without a reception buffer;
FIG. 5 is a time chart showing the data reception and the subsequent processing in the conventional data reception method having no reception buffer. In FIG. 5, the transmission completion line indicates a data transmission completion in a high state, and the reception completion line indicates a high state.
The state of h indicates the completion of data reception. The transmission completion check, reception, data processing, and state monitoring processing represent control transitions of the receiving device.

[0007] In FIG. 4 and FIG.
To read the transmission completion line and read whether data is coming. Then, in step 3, it is determined whether or not data has been received based on the result in step 2, and if it has already arrived, control is transferred to step 4; In step 4, a data line (not shown) is read and data is received. In step 5, the reception completion data is set in the reception completion line, and the next data transmission is requested to the transmission side. In step 6, the received data is processed. After step 6, start from step 2 again. On the other hand, in step 9, processing such as monitoring of the apparatus status is performed.

[0008]

However, in the above-mentioned conventional data receiving method, the internal processing for processing the received data (11 in FIG. 5) is carried out according to the transmission interval (12 in FIG. 5) on the transmitting side. In the case of high-speed operation, after the internal processing is completed, even if an attempt is made to receive data, the data has not yet arrived (13 in FIG. 5), that is, the transmission side has not set the transmission completion signal. turn into.

In general, a receiving apparatus must not only wait for data to arrive, but also perform other processing such as monitoring the state of the apparatus at the same time. (Step 9 in FIG. 4, FIG. 5
14). However, if the processing such as state monitoring takes much longer than the internal processing of data, even if the transmission side is in the data transmission completed state while performing the processing such as state monitoring, the receiving side apparatus will not be able to monitor the state. Data cannot be received until the processing of is completed. In other words, there is a problem in that the time (15 in FIG. 5) from when the transmitting side enters the data transmission completed state to when the processing such as state monitoring ends is overhead, and the processing start of the received data is delayed.

The present invention solves the above-mentioned problems of the conventional data receiving method, can prevent the occurrence of overhead, and can avoid delaying the start of processing of received data. It is intended to provide a data receiving method.

[0011]

Therefore, in the data receiving method of the present invention, data is transmitted and received by a synchronous transmission and reception protocol. And, when performing the reception of the data and the processing of the received data in synchronization, after finishing the processing of the received data,
Attempt to receive the next data, and when trying to receive the next data, if the next data has not been transmitted yet, do not start processing other than reception and receive the next data a preset number of times And retry.

This retry is performed an appropriate number of times according to the operating environment of the receiving apparatus, for example, the service cycle of the state monitoring process, and the interval at which data comes from the transmitting apparatus (host or the like).

[0013]

According to the present invention, in the data receiving method as described above, data is transmitted and received by the synchronous transmission and reception protocol. And, when performing the reception of data and the processing of the received data in synchronization,
After finishing the processing of the received data, try to receive the next data, and when trying to receive the next data, if the next data has not been transmitted yet, do not start processing other than reception, Attempts to receive the next data the set number of times. Upon completion of the processing of the received data, the receiving side attempts to receive the next data. However, if the next data has not been transmitted yet, the control shifts to data processing, processing unrelated to data reception, and the like. And checks again whether the next data has been transmitted. Then, the time from the completion of transmission of data on the transmission side to the reception of data on the reception side is minimized.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, the same parts as those of the above-described conventional technology will be described with the same reference numerals.
FIG. 1 is a flowchart illustrating a data receiving process according to the embodiment of the present invention. In this embodiment, the processing within the broken line is added to the conventional example of FIG. This process is to check (retry) a predetermined number of times whether data has come again when data has not yet come. Hereinafter, the data receiving process in the embodiment of the present invention will be described with reference to FIG.

First, in step 1, an initial value is set in a retry counter. Next, in step 2, the transmission completion line is read, and whether or not data is coming is read. Then, in step 3, it is determined whether or not data has been received based on the result in step 2, and if data has already been received, step 4
If not, control is transferred to step 7. In step 4, the data line is read and data is received. In step 5, the reception completion data is set in the reception completion line, and the next data transmission is requested to the transmission side. In step 6, the received data is processed. After step 6, start from step 1 again.

On the other hand, if data has not yet arrived in step 3, a retry is performed, and in step 7, the value of the retry counter is decremented by one. If all retries have not been completed yet in step 8, control is transferred to step 2 and retry is performed again. If data has not been received even after all retries have been completed, control is transferred to step 9 and processing such as device state monitoring is performed. I do.

FIG. 2 is a time chart showing data reception and subsequent processing in the embodiment of the present invention. This time chart shows an example in which the number of retries is 5 at the maximum. For the sake of comparison with FIG. 5, the respective meanings are the same. As in FIG. 5, processing of the received data (1 in FIG. 2)
After completion of 1), an attempt is made to receive the next data (1 in FIG. 2).
2). However, at this timing, the transmitting side has not yet completed data transmission. Therefore, the receiving device retries reception (13 in FIG. 2). The completion of data transmission can be confirmed in the fifth retry (14 in FIG. 2), and the data is immediately received and processed. Also, as shown in FIG.
If the completion of data transmission cannot be confirmed even after the fifth retry, data reception is abandoned, and control is transferred to the state monitoring process.

FIG. 3 is a block diagram showing the configuration of the data receiving apparatus according to the embodiment of the present invention. The main memory RAM 21, a retry counter 22 formed on the main memory RAM 21,
Program ROM 23, I / O circuit 24, MPU 25,
A clock generator 26 and an external interface 27 are provided. It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0019]

As described above in detail, according to the present invention, in the data receiving method, data transmission / reception is performed by the synchronous transmission / reception protocol. When the data reception and the processing of the received data are performed in synchronization with each other, after the processing of the received data is completed, the reception of the next data is attempted. If the data has not been transmitted yet, the processing other than the reception is not started, and the reception of the next data is attempted a predetermined number of times. Upon completion of the processing of the received data, the receiving side attempts to receive the next data. However, if the next data has not been transmitted yet, the control shifts to data processing, processing unrelated to data reception, and the like. And checks again whether the next data has been transmitted. Then, the time from the completion of transmission of data on the transmission side to the reception of data on the reception side is minimized. Therefore, it is possible to prevent the occurrence of the overhead and to prevent the start of the processing of the received data from being delayed.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a data receiving process according to an embodiment of the present invention.

FIG. 2 is a time chart showing data reception and subsequent processing in the embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a data receiving device according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a data receiving process in a conventional data receiving method.

FIG. 5 is a time chart showing data reception and subsequent processing in a conventional data reception method.

[Explanation of symbols]

 21 Main memory RAM 22 Retry counter

Claims (1)

(57) [Claims] 1. A data reception how in synchronous transmission and reception protocols, (a) receiving data, and the processing of the received data synchronized
If carried out by, after termination of processing of the received data
The attempts to receive the next data, when attempting to receive the (b) the next data, the following data
If not yet transmitted, without starting the processing other than reception, data reception how, characterized in that a set number of times in advance and attempts to receive the next data.