JPH0457437A - Data transmission controller - Google Patents

Abstract

PURPOSE:To transfer a command without revision of a format of a transmission frame data with common share of a data bus by providing a command reception means detecting a command transfer synchronizing signal synchronously with a data of a 1st byte of the command on the controller. CONSTITUTION:When a command reception means 6 receives an output of an output buffer full signal inverse of OBF, a command transfer synchronizing signal inverse of CMDS is checked and whether or not the signal is resident in a 1st byte of the command data is discriminated. When the signal inverse of CMDS is outputted from a host 2, a command reception pointer is cleared and a command reception state flag is set and the mode is transited to a command reception hand-shake. When the signal inverse of CMDS is logical H, the command reception state flag is checked, and when it is set, it is discriminated that the signal inverse of CMDS is resident in a 2nd or succeeding byte of the command and the command reception hand-shake processing is implemented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a data transmission control device that controls the transmission and reception of data of an information processing device, and particularly to a mechanism for transferring frames and commands from the information processing device. .

[Prior Art] FIG. 6 is a configuration diagram of a device disclosed in Japanese Patent Application Laid-Open No. 61-218248 entitled “Data Transmission Control Device”.

In the figure, a data transmission control device (1), an information processing device (hereinafter referred to as host) that performs data transmission with other terminals via this data transmission control device (1) (2), and a transmission line (3) are shown. , a transceiver that performs data level conversion (
4), transmit frame data receiving means (5) and bidirectional data bus (7) are shown. Data transmission control device (
1) is provided with a terminal connected to the host (2) by a handshake control line. Among these, the terminal (8
), the output buffer full signal OBF is input to the terminal (9), and the input buffer full signal IBF is input to the terminal (9). Terminal (1
The acknowledge signal ACK is output from the terminal (0), the strobe signal STB is output from the terminal (11), and the terminal (
12) contains 1 of the transmission data output from the host (2).
Transmission data synchronization signal TS output in synchronization with the first byte
YN is input.

The frame synchronization determination means (5a) of the transmission frame data receiving means (5) receives the transmission data synchronization signal TSYN (12
) to establish synchronization with the first byte of the transmission frame data. Also, frame synchronization control means (5b)
performs a data acceptance handshake after synchronization is established.

Note that (14) is the transmitting terminal Tx, and (15) is the receiving terminal R.
It is x.

FIG. 5 is an explanatory diagram of the format of transmission frame data. The frame in this figure consists of the number of bytes specified by the priority code (PR), source address (SA), destination address (DA), control code (CC), byte count (BC), and byte count (BC). n data (D
Tl) to (DTn), and a frame check code (FCC) for checking errors in packet units.

Next, the operation will be explained. FIG. 7 is a timing diagram showing the procedure when data output from the host (2) is input to the data transmission control device (1). When the host (2) issues a frame transmission request, an output buffer full signal OBF and a transmission data synchronization signal TSYN are set. When the frame synchronization determining means (5a) in the data transmission control device (1) detects that the output buffer full signal OBF is set, the frame synchronization determining means (5a) in the data transmission control device (1) responds to the transmission data synchronization signal T.
Check SYN. That is, by detecting that the synchronization signal TSYN is being output, it is detected that it is the first byte of the transmission data.

Thereafter, the frame synchronization control means (5b) in the data transmission control device (1) outputs an acknowledge signal ACK. When the acknowledge signal ACK is output, the host (2) outputs the transmission data in response to the output, and outputs the signals OBF and TSY.
Reset N.

The frame synchronization control means (5b) inputs data after confirming that the OBF has been reset, and inputs the acknowledge signal A.
Reset CK. From the second byte onward, the host (2) resets the transmission data synchronization signal TsYN and outputs data. The transmission frame data receiving means (5) in the pig transmission control device (1) recognizes that the data is from the second byte onward and inputs the data. When the transmission frame data receiving means (5) receives a counter BC representing the number of bytes of data as input from the data bus, it repeats the data receiving handshake for the number of data bytes and ends the data receiving. If the host (2) loses synchronization with the host side due to a power outage or other reasons during the data reception handshake, the frame synchronization determination means (5a) determines the current state at the time the transmission data synchronization signal TSYN is set. The transmission frame data is discarded and the reception of the transmission frame data is started again as the first byte PR.

After receiving all transmission frame data, the data transmission control device (1) performs processing such as adding start/stop bits and parity, performs parallel/serial conversion, generates serial data, and sends it to the transmission line (3). Start sending to.

[Problems to be Solved by the Invention] As described above, the conventional data transmission control device has a configuration in which only the transmission frame data is transferred from the information processing device to the data transmission control device, and information other than the transmission frame data is transferred. If a request occurred to be communicated to the data transmission controller, this could not be done.

This invention was made to solve this problem, and it is possible to accept a command transfer request from a host without changing the format of the transmitted data, and even when transmitting data is being received from the host. The purpose of this invention is to obtain a data transmission control device that can perform the following functions.

[Means for Solving the Problems] A data transmission control device according to the present invention detects a synchronization signal for transmission data transfer that is synchronized with the first byte of transmission data from a host, and receives transmission frame data. and command receiving means for detecting a command transfer synchronization signal synchronized with the first byte of data when transferring a command from the host and accepting the command.

[Operation] According to the data transmission control device according to the present invention, the command receiving means monitors the command transfer synchronization signal, and when the synchronization signal is set, the command is accepted. Therefore, data transferred from the host (information processing device) can be accepted as a command.

[Example] Next, the present invention will be explained in more detail with reference to an example shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a data transmission control device (1) according to the present invention.

The data transmission control device (1) according to this embodiment is provided with a command receiving means (6) in addition to a transmission frame data receiving means (5). This command receiving means (6
) is the command transfer synchronization signal CMD related to the terminal (13).
The host (2) monitors the host (2) and processes command data from the host (2).

The data transmission control device (1) is configured as, for example, a microcomputer. In this case, the transmission frame data receiving means (5) and the command receiving means (6) are realized as a program stored in R Oki built in the microcomputer.

Next, the operation will be explained. Fig. 2 is a timing diagram showing the procedure for receiving transmission frame data and command data from the host, Fig. 3 is a flowchart showing the operation of the command receiving means and sending data receiving means, and Fig. 4 is a diagram showing the command format. It is.

In this embodiment, the command transferred from the host (2) to the data transmission control device (1) has a variable length of 1 to 5 bytes, and the byte length is controlled by the first byte (CO) of the command.
Bit 0 (bo) of MM).

1 (bl). The data transmission control device (1) is
First, the output buffer full signal OBF is notified from the host (2) when transmitting frame data or commands are transferred.
(Figure 3, Sl). When the command receiving means (6) detects the output of the output buffer full signal OBF, the command transfer synchronization signal CMDS is then checked to determine whether it is the first byte of command data (S
2).

At this point, if CMDS is output from the host (2), clear the command acceptance pointer (S4), set the command acceptance flag to ONL, and execute command acceptance hand (S4).
Proceed to S5).

If CMDS (13) is “High” (no signal is output from host (2)), check the command acceptance flag (S3), and if it is ON, determine that it is from the second byte of the command and perform command acceptance handshake processing. I do(
S5). After the command acceptance handshake, the command acceptance means (6) determines whether all the commands have been accepted by comparing the command acceptance pointer and the byte count section of COMI, and if the command has not been completed, returns to the process of waiting for the OBF signal and executes the command. Repeat this until the acceptance is complete (
S6). Next, the command receiving means (6) checks whether or not a transmission frame was being received at the time when all the commands were received, and if it was in the middle of receiving transmission frame data, it performs data acceptance processing (S7).

If it is determined in S3 that the command is not being received, the process moves to the operation of the transmission frame data receiving means (5),
The transmission frame data synchronization signal TSYN is checked. If TSYN is being output at this time, the transmission frame data reception counter is cleared, the transmission data reception flag is turned ON, and reception of transmission frame data is started (S9). If TSYN is not output from the host (2), it is determined that the second byte and subsequent transmission frames are being received, and data reception is started (SlO).

The number of repetitions of transmitting frame data reception is determined by the byte count BC indicated in the frame data,
When the transmission data reception has been completed a specified number of times, the transmission frame data reception is completed (S11).

Note that steps 81 to S7 described above are realized by the command receiving means (6) according to the present invention, and steps S8 to S11 are realized by the transmitted data receiving means (5).

In this embodiment, since command reception is prioritized during reception of a transmission frame, if a command reception request is made during reception of a transmission frame, the signal between the host and the data transmission control device is changed as shown in Figure 2. It behaves like. FIG. 2 shows that the host transfers a 1-byte command after transferring 2 bytes of transmit frame data, and then transfers the transmit frame data again starting from the 3rd byte after the command transfer is completed.

[Effects of the Invention] As described above, the present invention has a configuration including a command receiving means that detects a command transfer synchronization signal that is synchronized with the first byte data of a command. Commands can be transferred by sharing the data bus.

Moreover, even if a command is transferred during reception of transmission frame data, it is possible to receive the command transfer with priority, and it is possible to obtain a data transmission control device that can accept and accept commands at any time.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a data transmission control device according to an embodiment of the invention, FIG. 2 is a timing diagram of the embodiment of the invention, FIG. 3 is a flowchart of the operation according to the embodiment of the invention, and FIG. 4 is a command format diagram according to an embodiment of the present invention, FIG. 5 is a conventional data format diagram,
FIG. 6 is a block diagram of the conventional device, and FIG. 7 is a timing diagram of the conventional device. In the figure, (1) is a data transmission control device, (2) is an information processing device, (3) is a transmission line, (4) is a transceiver, (5) is a transmission frame reception means, and (6) is a command reception means. , (7) is a bidirectional data bus, (8) to (
13) is a terminal, (14) is a transmitting terminal, and (15) is a receiving terminal. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent: Patent attorney Yoshi 1) Kenji (2 others) Data transmission control device 2: Host 3, transmission driver/4 driver 5: Transmission frame data receiving means 6: Command receiving means 7, bidirectional data bus implementation FIG. 1: Command formant diagram of the embodiment. FIG. 4: Conventional data formant diagram. FIG. 5: Data transmission control device 4: Transmitter FIG. 6

Claims (1)

[Claims] In a data transmission control device that is connected between an information processing device and a transmission line and controls data transmission and reception of multiple information processing devices via the transmission line, synchronization with the first byte of data sent from the information processing device is performed. a transmission frame data receiving means that detects a transmission data transfer synchronization signal to receive the transmission data and receives the transmission data; and a transmission frame data reception means that detects a command transmission synchronization signal that synchronizes with the first byte of data at the time of command transfer from the information processing device and accepts the command. 1. A data transmission control device comprising: command receiving means for executing a command.