JPS60206246A - Data transmission system - Google Patents

Abstract

PURPOSE:To restore and transmit data, and to improve reliability by allowing a main device to send out data continuously even after a clock signal is transmitted by one record of the data when a reception side detects a data transmission error. CONSTITUTION:If there is a transmission error when an operating device transmits data to the main device, the microcomputer 7 of the main device sends a clock to the microcomputer 2 of an operation display device by one data as shown by 15 and then sends the clock continuously by another data without stopping as shown by 16. Said microcomputer 2 monitors the interval between a clock inputted from 5 and the next clock all the time and decides that data received previously is not received normally when the interval from the reception of the clock for sending the final data bit of one data to the reception of the next clock is <=1.5 time as long as a normal interval, thereby resending the same data as shown by 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a data transmission method used for exchanging information between a separate operation display section and a main device in a wireless transmitter/receiver or general electronic equipment.

(Prior art and its problems) In order to improve operability, an increasing number of recent electronic devices are adopting so-called operation-separated type remote controls in which the operation display section is separated from the main device. In such cases, it is required to reduce the number of signal lines between the controller and the main device as much as possible.1 For example, for devices that only require unidirectional transmission, such as remote control devices for home televisions, infrared or ultrasonic Wireless technology has also been realized using .

The most common way to reduce the number of signal lines is to transmit data using serial pulse codes, and conventionally, the start-stop synchronization method has been most commonly used as this encoding method.

Also, recently, it has become advantageous in various aspects to use microcomputer for the main device and operation display mentioned above. In this case, start-stop synchronization is a method based on reproducing bit synchronization from the data code string during decoding, but since this requires processing that varies by more than one order of magnitude with respect to the baud rate of the transmitted data, There is a problem of increasing the load factor of the computer, and especially low-priced 4-bit microcomputers have slow processing speeds, which makes it difficult to multiplex the original six processes necessary for operation display and data transmission processing. There are some drawbacks.

As a means to solve this problem, LS for asynchronous transmission control is
There is a method of connecting to a microcomputer via I, but the price of this LSI is equal to or more than that of a microcomputer, so it is disadvantageous to use this method for low-priced products. .

On the other hand, GP IB (
IEEE 5 standard 488-1978).

This requires an 8-bit parallel data line and a plurality of control signal lines, which does not meet the objective of reducing the number of signal lines.

In order to solve the above problems, there is a method in which data can be transmitted between the main device and the operation display by simply using two signal lines, a data signal line and a clock signal line.

This data transmission method will be explained below.

Data is exchanged between the main device and the operation display in synchronization with a clock signal sent from the main device to the operation display. Therefore, the load on the microconbeater required for synchronization can be reduced.

Further, the direction of data exchange is determined as follows.

When the level of the data signal line is 9 normal mark hold, when transmitting data from the operation display to the main device, the microcomputer built in the operation display sets the level of the data signal line to space.

The microcomputer built into the main device regularly monitors the level of the data signal line, and when the level of the signal line reaches the space, it determines that there is a transmission request from the operation display side, and the operation display A clock is applied to the microcomputer through the clock signal line, and the main device enters data reception mode. The operation display transmits data in synchronization with the given flock.

On the other hand, when transmitting data from the main device to the operation display,
After confirming that the microcomputer of the operation display is not making a transmission request, the main device gives a clock to the microcomputer of the operation display through the clock signal line and enters the data transmission mode.

The microcomputer built into the operation display enters data reception mode when a clock is applied while not making a transmission request.

Furthermore, the data signal line has space priority.

If either the main device or the operation display becomes a space, the level of the data signal line will be spaced fx even if one outputs a mark.7).

Therefore, if the main unit and operation display switch to data transmission mode at the same time, and the operation display outputs a space while the main unit is outputting a mark, the resulting level of the data signal line will be becomes a space.

The microcomputer in the main unit is designed to constantly monitor the level of the data signal line, and monitors whether the data signal line is at the space level even though the main unit has output a mark. It is possible to avoid data collision by determining that a data collision has occurred, returning to the initial state and switching to reception mode.

The problem here is that although the data transmission/reception mode is normal, a data recovery means is required in case there is a data transmission error due to a disturbance in the signal line or the like.

(the purpose) The purpose of the present invention is to solve this problem.

When there is a data transmission error, the data receiving side retransmits the data that had an error in the transmission without sending back a new Nack data to the transmitting side to recover the data. Our goal is to provide the following.

(Example) This invention will be explained below with reference to FIG. 1, FIG. 2, and FIG. 3.

FIG. 1 shows the circuit configuration of the present invention.

A data input terminal 3, an output terminal 4, and a clock input terminal 5 are connected to a microcomputer 2 built in the operation display 1.

The signal output from the output terminal 4 of the microcomputer is wire-ORed with the signal at the input terminal 3 via an inverter.

On the other hand, a data input terminal 8 and an output terminal 9 are connected to a microcomputer 7 built in the main device 6. Similar to the operation display 1, the signal output from the output terminal 9 is wire-ORed with the signal at the input terminal 8 via an inverter.

Further, the main device has a built-in clock generator 11, and the output of this clock is controlled by a control output signal 10 of the microcomputer of the main device. The clock output by the control output signal is applied to the clock input terminal 5 of the microcomputer of the operation display and also to the clock input terminal 12 of the microcomputer of the main device.

FIG. 2 shows the levels of the data signal line and clock signal line when data is transmitted from the operation display to the main device.

13 indicates the level of the data signal line. 14 is.

Indicates that the same data has started to be sent again when a data transmission error occurs. 15 is the level of the clock signal line. Reference numeral 16 indicates a clock for retransmitting the data indicated by 14.

FIG. 3 shows the levels of the data signal line and clock signal line for transmitting data from the main device to the operation display.

Reference numeral 17 indicates a change in the level of the data signal line obtained by output from the microcomputer 7 of the main device.

Reference numeral 18 represents a change in the level of the data signal line output by the microcomputer 2 of the operation display (the last 3 in the data signal line indicated by 19).
There are marks or spaces between the bits.

20 is the level of the clock signal line. Reference numeral 21 is a clock signal not shown at 19 for outputting 3 bits of data.

The data recovery procedure when a transmission error occurs will be explained below. The data sent from the main device to the operation display and the data sent from the operation display to the main device both have a 1-bit even parity bit field, and the receiving side determines that there is a data transmission error by performing a parity check. do.

If there is a transmission error when transmitting data from the controller to the main device, the microcomputer 7 of the main device will continue to transmit the clock signal shown in 15 to the microcomputer 2 of the operation display for one data minute. Without stopping, it continues to send out one more data as shown in 16. The microcomputer 2 on the operation display constantly monitors the interval between the clock manually input from 5 and the next clock. If the interval is shorter than the normal value of 1.5 times, it is determined that the previously transmitted data was not received normally, and the same data is transmitted again as shown at 14.

The microcomputer 7 of the main device can recover the data by receiving the retransmitted data again.

According to this method, the main device does not need to send new data to inform the operation display that there was an error in the previously received data, and can immediately re-receive the data that caused the transmission error. On the other hand, a case will be explained in which there is a transmission error when data is transmitted from the main device to the operation display.

After the data is sent from the main device's microcomputer 7 to the operation display's microcomputer 2 as shown in 17, the same 3-bit data is sent from the microcomputer 2 to the microcomputer 7 as shown in 19.21. Send the data back. When this data is marked, ac
k, a space indicates a NACK, and the microcomputer in the main device acknowledges the transmitted data as an ACK if 2 or more bits of the 3 bits of returned data are marks.
If 2 or more bits are spaces, it is determined as Nack.

According to this method, the main device performs an ACK/ACK of the transmitted data.
You can always check the Nack judgment, and there is also a 3-bit ac
Since the k/Nack data can be determined by majority decision, the reliability of data transmission can be improved.

Data transmission from the main device to the operation display, or.

In any case of data transmission from the operation display to the main device, ack/nack information when a data transmission error occurs can be included in the data without providing a new control signal line.

(Effect) With this invention, when a transmission error occurs when transmitting data from the operation display to the main device, the data can be immediately retransmitted without simply transmitting the information to the operation display. be able to. On the other hand, if a transmission error occurs during data transmission from the main device to the operation display, the main device can always monitor this, improving the reliability of data transmission. A new control line is provided for ack/nack information.

There is no need to send new data, and all data can be included in one data.

[Brief explanation of the drawing]

FIG. 1 shows the hardware configuration of the data transmission system of the present invention.
Figure 2 is a data transmission procedure diagram from the operation display to the main device.
FIG. 3 is a data transmission procedure diagram from the main device to the operation display. 1: Operation display, 2: Microcomputer. 3: data input terminal, 4: data output terminal, 5: clock input terminal, 6: main device, 72 microcomputer,
8: Data input terminal, 9: Data output terminal, 10: Chronograph control terminal, 11: Chronograph generator, 12: Chronograph input terminal, 13: Data from operation display to main device, 14: From operation display to main device retransmission data to, 15
: Clock, 16: Data retransmission request data, 17: Data from the main device to the operation display, 18; 4° terminal output when the operation display is receiving data, 19 Ack/Nack sent from the operation display to the main device Data, 20:ri07ri,
21: Clock for transmitting ack7/N1ck data. Figure 1

Claims (1)

[Claims] The main device and the slave device are connected by a data signal line and a clock signal line, and when the receiving side detects a data transmission error from the main device to the slave device, the slave device transfers the data from the slave device to the main device. In this transmission, the main device transmits the clock signal for the number of data records, and by continuing to send it even after the transmission is completed, the slave device detects a transmission error and retransmits the data in synchronization with the clock. In addition, in transmission from the main device to the slave device, an ack/Nack field is provided in the data code to be transmitted, and when the main device finishes transmitting data, the slave device transmits Nack data at the timing corresponding to the field. A data transmission method characterized by having the main device detect a transmission error and resend the data.