JPH0374559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 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 transceiver or general electronic equipment.

BACKGROUND OF THE INVENTION In recent years, an increasing number of electronic devices are adopting so-called operator-separated type remote controls in which an operation display section is separated from a main device in order to improve operability.

In such cases, it is necessary to reduce the number of signal lines between the controller and the main device as much as possible.For example, for devices that only require unidirectional transmission, such as remote control devices for home televisions, it is necessary to use infrared or ultrasonic waves. Wireless technology has also been realized. The most common way to reduce the number of signal lines is to transmit data by serial pulse coding, and the start-stop synchronization method has conventionally been most commonly used for this encoding method.

Recently, it has become advantageous in various aspects to use microcomputers for the main devices and controllers mentioned above, but when trying to implement encoding and decoding using the start-stop synchronization method using a microcomputer, Start-stop synchronization is a method based on reproducing bit synchronization from the data code string during decoding, but this requires processing that is one order of magnitude faster than the bit rate of the transmitted data, which increases the load on the microcomputer. In particular, low-priced 4-bit microcomputers have slow processing speeds, which makes it difficult to multiplex the original processing required for operation display and data transmission processing. . One way to solve this problem is to connect it to a microcomputer via an LSI for asynchronous transmission control, but the price of this LSI is equal to or more than that of a microcomputer, making it a low-cost product. It is disadvantageous to adopt this method.

On the other hand, as a known data transmission method that can reduce the load factor of the microcomputer,
There is GPIB (IEEE Standard 488−1978),
This method requires 8-bit parallel data lines and a plurality of control signal lines, and does not meet the objective of reducing the number of signal lines.

The object of the present invention is to eliminate these drawbacks and provide an economical data transmission system that reduces the number of signal lines and the load factor of a microcomputer.

Another object of the present invention is to enable predetermined data transmission on a multi-drop transmission line in which n child devices are connected to one new device.

In the case of data transmission between the main device and a separate operation display built in a microcomputer, the conventional method (1) increases the load on the microcomputer.

(2) The number of signal lines between the main device and the operation display increases.

(3) There is a cost problem when using an LSI dedicated to communication.

There are drawbacks such as:

In the present invention, in order to eliminate these drawbacks, data can be transmitted from the main device to the microcomputer built in the operation display using only two signal lines, the data signal line and the clock signal line. invented a method. Data is exchanged between the main device and the operation display in synchronization with a clock signal sent from the main device. Therefore, the load on μ-com required for data synchronization can be reduced.

Furthermore, the direction of data exchange is determined as follows. When transmitting data from the operation display to the main device when the data signal is normal and mark hold, the μ-com of the display makes the signal line a space. The main device regularly monitors the signal line, and when the signal line becomes empty, it determines that it is a transmission request from the operation display, and as soon as it gives the clock to the display, it enters reception mode and the μ-com of the display transmits. Receive the data to be sent. When transmitting data from the main device to the operation display, the main device applies a clock to the display and at the same time enters the transmission mode and sends the data to the μ-com of the display.

Note that space is given priority to the data signal line, so if either the main device or the operation display becomes a space, the signal line becomes a space even if one of them is used for mark output. Therefore, while the transmitting side is transmitting data, the receiving side samples the data while holding the mark.

FIG. 1 is a block diagram of data transmission between an operation display and a main device in the present invention.

1 is a block showing the entire operation display, 2
is a microcomputer built into the operation display.

The terminal 3 in the microcomputer 2 is an input terminal for inputting the signal from the main device, and the terminal 4
is an output terminal for data output from the microcomputer 2. This output data is connected to the input terminal 3 through the inverter 18, forming a data signal line.

5 is an interrupt signal (clock) sent from the main device
This is an interrupt input terminal that accepts an interrupt signal, and data is exchanged in synchronization with this interrupt signal. 6 is a block representing the main device, and 7 is a microcomputer built in this main device for controlling communications. 8 is a terminal for inputting an output signal from the operation display, 9 is an output terminal for outputting data to the operation display via an inverter 19, and input terminal 8 and connection 10 are for interrupting to the microcomputer of the operation display. This clock generator is controlled by 11 gate signals. 12 is microcomputer 7
This is an input terminal that is itself interrupted by the same clock.

FIG. 2 is a time chart of data and interrupts (clocks) when data is sent from the operation display to the main device. 13 is a diagram illustrating the transition of data when data is transmitted from the operation display to the main device on the data signal line. 14 is an interrupt signal generated at this time.

This operation will be explained below.

The signal line is normally high level, and low level is given priority. That is, output terminal 4 or 9 in FIG.
Either one of the signal lines goes low through the inverter
When the signal line is set to
Hold low level. When the operation display unit sends data to the main unit, first connect the signal line.
Set it to Low and send a transmission request to the main device. The main device monitors the signal line at regular intervals,
As soon as it is detected that the operation display is issuing a transmission request at a certain point in time, a signal to open the clock gate is outputted from the terminal 11.

The clock signal begins to interrupt the microcomputers of both the operation display and the main unit.

The microcomputer of the display device accepts this interrupt and moves on to interrupt processing. In interrupt processing, it is determined what kind of data is to be output, and the data is output to the signal line accordingly. In contrast, the main device's microcomputer samples the data output from the operating device using the same interrupt signal.
Interrupt signals are generated in constant cycles, and each interrupt process is completed before the next interrupt occurs, and one bit of data is sampled for each interrupt. The record length of the data sent from the operation display to the main unit is fixed, and after outputting the clock a prescribed number of times, the main unit outputs a signal to close the gate from terminal 11, thereby terminating the interrupt. At this point, the data is complete.

FIG. 3 is a time chart of data and interrupts (clocks) when data is sent from the main device to the operation display. 15 is a diagram showing the transition of data when data is transmitted from the main device to the operation display through the data signal line. 16 is an interrupt signal generated at this time.

This operation will be explained below.

When the data signal line is low, that is, there is no transmission request from the operation display, the main device's microcomputer outputs a signal to open the clock gate, and the microcomputer of the operation display and the main device's microcomputer themselves Add complexity. The microcomputer of the main device outputs data to the operation display when an interrupt occurs. At the same interrupt, the microcomputer of the operation display samples the data output from the main unit. The record length of data sent from the main device to the operation display is fixed, and after the main device outputs the clock a specified number of times, it closes the clock gate and ends the interrupt. At this point, the data is complete.

FIG. 4 is a diagram in which n operation displays are connected to one main device in a multi-drop manner (n: positive integer).

FIG. 5 shows the structure of data sent from the main device to the operation display or from the operation display to the main device.
17 represents a data 1 record, an ID field is added to the beginning of this record, and each operation display device has a different ID number.

This operation will be explained below.

When data is sent from the main device to an operation display with a specific ID number, this data is transmitted equally to n operation displays connected to it, but the microcomputer built into each operation display analyzes this data, The ID number at the beginning of the data is compared with the ID number assigned to itself, and if they do not match, the given data is invalidated. Therefore, the number of operation display devices that can receive sent data and execute processing in accordance with the data is limited to one operation display device whose ID number of the data matches its own ID number.

On the other hand, when sending data from an operation display to the main device, the ID number assigned to each operation display is added to the beginning of the data, so the main device cannot send data from any of the multiple operation displays. It is possible to judge whether the

As explained above, according to the present invention, in data transmission between the main device and the operation display, the main signal lines can be reduced to two, the data signal line and the clock signal line, without increasing the load on the microcomputer that controls communication. be able to.

Further, data can be transmitted to each individual operation display even in a multi-drop transmission line in which n operation displays are connected to one main device.

[Brief explanation of drawings]

FIG. 1 is a block diagram for data transmission between the main device and the operation display. FIG. 2 is a time chart when data is sent from the operation display to the main device. FIG. 3 is a time chart when data is sent from the main device to the operation display. FIG. 4 is a diagram when n operation display devices are connected to one main device using a multi-drop transmission line. Fifth
The figure shows the structure of data sent and received between the main unit and the operation display. 1: Operation display block, 2: Microcomputer built into the operation display, 3: 2 microcomputer data input terminal, 4: 2 microcomputer data output terminal, 5: 2 microcomputer assignment 6: Main unit block, 7: Microcomputer built into the main unit, 8: 7 microcomputer data input terminal, 9: 7 microcomputer data output terminal, 10: Clock Generator, 11:7 microcomputer clock gate control signal output terminal, 12:7 microcomputer interrupt (clock) input terminal, 1
3: Time chart of data sent from the operation display to the main device, 14: Time chart of the clock when sending data from the operation display to the main device, 1
5: Time chart of data sent from the main device to the operation display, 16: Time chart of the clock when sending data from the main device to the operation display, 1
7: Structure of data exchanged between the main device and the operation display.

Claims (1)

[Claims] 1. In a data transmission method in which the operation display section of a wireless transceiver or electronic device is separated from the main device and signals are exchanged between the operation display section and the main device, the operation display section and the main device are separated from each other. In a configuration in which a single data signal is connected to a clock signal line and a single clock source is placed on the main device side, the clock source is shared and bidirectional communication is performed using a half-duplex system. A data transmission method characterized by: 2 In a multi-drop transmission line in which n operation displays are connected to one main unit, the operation display and the main unit are each connected by one data signal line and one clock signal line, and a single clock source is connected to the main unit. By sharing the clock source and providing an ID field for exchanged data, half-duplex bidirectional communication is possible between one of the n operation display units and the main unit. A data transmission method characterized by performing the following.