JPS5854426A - Data transfer system - Google Patents

Abstract

PURPOSE:To transfer data through two transfer lines after checking whether data reception is possible or not in both transfer lines and to prevent transfer from malfunctions by utilizing one code not used for the transfer of data as a control code indicating the permission of transfer. CONSTITUTION:Transfer from a main MPU to a sub-MPU is executed in the same manner as an ordinary one. The sub-MPU outputs a request signal requesting data transfer to the main MPU while keeping a reverse transfer line at its high level. In said condition, the sub-MPU is in data acceptable status and waits data transfer from the main MPU. Detecting said request signal, the main MPU sends a notice signal (t12-t13) and then a transfer permission code to the sub-MPU through a forward transfer line. By said operation, the main MPU is in data acceptable status and waits data transfer from the sub-MPU through the reverse transfer line. Receiving the transfer permission code, the sub-MPU returns the reverse transfer line to the low level. After checking the transfer permission code (t15), the sub-MPU transfer data (t16-t17) through the reverse transfer line.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transfer method between multiple microprocessors (hereinafter referred to as MPUs) used to control electronic equipment, and uses two transfer paths to easily and reliably transfer data between multiple microprocessors (hereinafter referred to as MPUs). The purpose is to perform bidirectional data transfer.

The basic configuration of a data transfer system having two transfer paths between two MPUs is shown in FIG. 1c. In such a configuration, when data is transferred bidirectionally between both MPUs, and at that time, the data is transferred after confirming that the other λ (PU) is in a receptive state. It was done like this.

Tore indicates the case of transfer from the main MPtJ to the secondary MPU,
Further, the data length of the transmission data is determined in advance and set in a fixed length format, which is assumed here to be 8 pits. In addition,
The waveform during transfer is shown in Figure 2. In a steady state, both the forward transfer path and the reverse transfer path are at LOW level (logic level L).
The OV level is hereinafter abbreviated as L level. Similarly, it is maintained at I (high level is hereinafter abbreviated as H level). first,
The main MPU sets the forward transfer path to H level (1+ in Figure 2).
). This is a notice of transfer and is called a notice signal. At the same time, it monitors the reverse transfer path and waits for a signal indicating acceptance from the sub MPU. When the sub MPU detects the H level of the forward transfer path, that is, the advance notice signal, it prepares for acceptance and sets the reverse transfer path to H level (t in FIG. 2). This means that reception is possible and is called an acceptance signal. At the same time, the secondary MPU monitors the forward transfer path and waits for data to be transferred.

When the main MPU detects the H level of the reverse transfer path, that is, the acceptance signal, it learns from Tok that the sub MPU is ready to accept data. Here, up to this point, the forward transfer path is H
However, at this stage, the forward transfer path is brought to L level (second @ts). That is, the warning signal ends, and then data (14-ts) continues. There are various methods for this data, but in Sasa2 rg+, the period of the pulse interval is 0, 0,
An example of a method for distinguishing 1 is shown.

Also, an example of data length of 8 bits is shown. In this figure, “0”
]101001J is shown. Secondary MPU
starts receiving this data. At the same time as this data reception starts, the reverse transfer path is returned to the L level. Note that since the data length is fixed, there is no need for a code to indicate the end of data. By the above procedure, from the main MPU to the sub MPUK
The desired data is transferred.

Next, in the case of transfer from the sub-MPU to the main MPU, in this case, the positions of both MPUs in the case of transfer from the main MPU to the sub-MPU are switched, and exactly the same procedure is performed. Then, the sub MPU sends a notice signal K to set the reverse transfer path to H level, sends an acceptance signal from K to set the main MPUU forward transfer path to H level, and the sub MPU detects this acceptance signal. After that, the data is transferred via the reverse transfer path.

Bidirectional data transfer is possible through the steps described above.

However, this conventional method has the following drawbacks. First, considering the case where the main MPU and the secondary MPU try to start data transfer at the same time, in this case, the main MPU
sets the forward transfer path to H level as a warning signal. Since the sub MPU is also attempting to transfer data at the same time, the reverse transfer path is set to H level as a warning signal. However, from the above-mentioned procedure, the notice signal from which sub-MPU is
The PU mistakenly recognizes it as an acceptance signal. Therefore, wU
Although the MPU is not in a ready state, the main MPU
This is manifested in the fact that data is transferred to the secondary MPU. Naturally, the secondary MPU cannot receive this data and the purpose cannot be achieved.

Therefore, in the conventional method, when both MPUs try to transfer data at the same time, an erroneous transfer occurs, and in a system where reliable transfer is required,
This method will not be applicable. In addition, warning signals,
The method of using a code instead of simply setting the reception signal to the H level does not have the above disadvantages, but in this case, the transfer procedure also requires line inspection, and the burden on the MPU in both cars increases, making the MPU Other places f! If we give jK limit, then K
Become. - This invention solves the drawback of the conventional method, namely, the erroneous transfer when attempting to perform simultaneous transfer.

Mass, use one of the unused data codes transmitted by this system. Example 1:

Two-digit BCD data (
8-bit length), for example, FF
The code (displayed in hexadecimal) is not used. This code is used and defined as a control code indicating transfer permission. Below-1 This code is called the transfer permission code, and this transfer permission code is used for other general transfer data, that is, the data to be transferred between the main MPU and the sub MPU (as mentioned above, if the 2-digit BCD Since the data (data) and code length are circular, it can be handled in exactly the same way as general transfer data. Note that the general transfer data is given a name, and the data transferred from the main MPU to the sub MPU is hereinafter referred to as data A, and the data transferred from the sub MPU to the main MPU is
The data transferred to is hereinafter referred to as data B.

Here, to explain the transfer method, first, the transfer from the main MPU to the sub-MPU uses the same means as in the past. That is, the procedure is performed by transmitting a notice signal from the main MPU, a reception signal from the sub-MPU, and data A from the main MPU.

Further, the transfer from the sub-MPU to the main MPU is performed as follows. The waveform at that time is shown in FIG.

First, the sub MPU sets the reverse transfer path to H level (Fig. 3,
tll). This signal is used to indicate to the main MPU that a transfer is desired and to request permission for the transfer, and is hereinafter referred to as a request signal.

In this state, the secondary MPU is ready for reception, monitors the forward transfer path, and waits for the transfer from the main MPU.

When the main MPU detects the request signal, it sends a notice signal (t12-t13) and then a transfer permission code (t14-t1.) via the forward transfer path.

At this point, the main MPU becomes ready for reception and waits for transfer data, ie, data B, from the sub MPU via the reverse transfer path. In addition, in Figure 3, the transfer permission code is assumed to be F.
F (hexadecimal display). The secondary MPU returns the reverse transfer path to the L level at the same time as it starts receiving the transfer permission code.

When the secondary MPU receives this and confirms that it is a transfer permission code (1, .), it transfers the target data B (Zsa to t1.) via the reverse transfer path. The main MPU receives this data B and the purpose is achieved.

By the way, the case where the transfer permission code is not the transfer permission code in tll will be described. Normally, a transfer permission code is sent here, but in some cases data A may be sent. The reason for this will be discussed later, but in any case, the deputy MP
After U receives this, it repeats from the beginning, ie, from the request signal.

That is, the secondary MPU checks the code sent at the time of tllll, and if the code is the transfer permission code, the sub MPU sends the code at t1.
Do steps 6 onwards. Also, the code sent is data A
I received the Awaba Kone, and then I read it again from tll.
I'll return it.

Incidentally, in the conventional method, a problem occurred when both MPUs tried to transfer data at the same time, but this method shows that this problem does not occur.

Now, assume that both MPUs attempt to transfer data at the same time. First, the main MPU sets the forward transfer path to H level and sends a warning signal. At the same time, the secondary MPU connects the reverse transfer path to H
level and sends a request signal. In this case, the main MPUFi
This request signal is mistaken for an acceptance signal a! data A is transferred via the forward transfer path. However, unlike the conventional method,
Since the secondary MPU is in a receptive state at this point, it receives this transfer data. Note that this state corresponds to the above-mentioned "case where data A is originally sent to the transfer permission code". At this point, the data transfer from the main MPU to the secondary MPU has been completed, ie, no problems arise as in the conventional system. Now, as a secondary MPU, what was transferred was not the transfer permission code but data A, so
Repeat from outputting the request signal again. As a result, following the procedure of tll " tty in FIG.
Data transfer to the PU will be accomplished.

With the above means, the present invention can perform data transfer in both directions with two transfer paths and after confirming whether or not both MPUs can accept data in a simple manner, and also prevents transfer errors. It is possible to provide a reliable data transfer method without any problems.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration block diagram of a data transfer system having two transfer paths, FIG. 2 is a waveform diagram of a conventional transfer method, and FIG. 3 is a waveform diagram of reverse direction transfer according to the present invention.

Claims (1)

[Claims] Two microprocessors C and below, h as the main MPU,
In an electronic equipment control system consisting of a secondary MPU (hereinafter referred to as a forward transfer path), a transfer path (hereinafter referred to as a forward transfer path) connecting an output-only terminal of the main MPU and an input-only terminal of the sub-MPU;
Both MPUs are connected by two transfer paths (hereinafter referred to as reverse transfer paths) that connect the human power-only terminal of the P TJ and the output-only terminal of the sub-MPU.
When performing data transfer to U, the main MPU sends a notice signal via the forward transfer path, and in response,
When the MPU sends an acceptance signal via the reverse transfer path, a method is used to transfer the target data in fixed length format via the forward transfer path, and data is transferred from the secondary MPU to the main MPU. , the secondary MPU sends a request signal via the reverse transfer path, and in response, the main MPU sends a notice signal via one transfer path, followed by a transfer permission code in fixed length format, and when it is red, the request signal is sent via the reverse transfer path. A data transfer method that uses a means to transfer target data in a fixed length format and performs bidirectional data transfer over two transmission lines using stiff means.