JPS62102647A - Interface circuit - Google Patents

Abstract

PURPOSE:To eliminate the need for a processor and to reduce a circuit scale by allowing a ROM to use to own output so as to apply the input control to itself. CONSTITUTION:A ROM 3, when a count inputted from counters 1, 2 is an even number, outputs a specific pattern not in an external device data and inputs it to a latch circuit 4. Further, a specific pattern is detected by specific pattern detection circuit 8, an FF 7 uses it as a data read pulse to read a device internal data from a data memory 6 and inputs the result to the ROM 3. The ROM 3 outputs an external device data corresponding to the device inside data and outputs it via the circuit 4 and a parallel/serial converter 5. The ROM 3 outputs a specific pattern to apply input control and repeats it to eliminate the processor thereby reducing the circuit scale.

Description

[Detailed Description of the Invention] [Summary] When converting device internal data into data for external devices and sending it out using the start-stop synchronization method, a read-only memory (hereinafter referred to as RO) is used.
M) outputs a specific pattern that does not exist in the external device data, inputs the device internal data, outputs the corresponding external device data based on this input, and then outputs the specific pattern. The circuit scale is reduced by repeating the same operations one after another, using its own output to control the input to itself.

[Industrial application field]

The present invention converts device internal data into data for external devices, such as an interface circuit between the transportation device and a printer, which is used when collecting error information on a line and printing it out. This invention relates to the improvement of an interface circuit that transmits data in a synchronous manner.

It is desirable that the circuit scale of the above interface circuit be small.

[Prior art and problems to be solved by the invention] Conventionally, in an interface circuit that converts internal data of a device into data for an external device and sends it in an asynchronous manner, a processor,
It uses RAM, ROM, etc. that stores external device data and execution command programs corresponding to each device's internal data, and inputting the device's internal data to the ROM is performed under the control of the processor, so the circuit size is large. There is a problem.

Measures to Solve Problem c] The above problem can be solved by writing data for external devices corresponding to the internal data of each device and a specific pattern that does not exist in the data for external devices in read-only memory, and This book repeats the process of inputting device internal data by outputting the specific pattern, outputting data for an external device corresponding to this input, and then outputting the specific pattern. The solution is provided by the inventive interface circuit.

[Effect]

According to the present invention, by outputting a specific pattern that does not exist in the external device data from the ROM, the internal data of the device is manually input, and by this input, the corresponding external device data is output, and then the corresponding data for the external device is output. By repeatedly outputting a specific pattern, so-called using its own output to perform manual control over itself, a processor for this purpose is unnecessary and the circuit size is reduced. .

〔Example〕

FIG. 1 is a block diagram of an interface circuit according to an embodiment of the present invention, FIG. 2 is a time chart of waveforms of each part in FIG. 1, and (A) to (,, T) are points 8 to 1 in FIG. 1. It corresponds to FIG. 3 is an explanatory diagram of the operation of the ROM shown in FIG. 1.

In the figure, 1 and 2 are counters, 3 is ROM, 4 is a launch circuit,
5 is a parallel-to-serial converter, 6 is a data memory, 7 is a flip-flop, and 8 is a specific pattern detection circuit.

Inputs A and B of ROM3 are input by counters 1 and 2 as shown in Figure 2 (
B) and <0. l 2゜3.4.
The count value of ... is input.

When this count value is an even number, the ROM 3 outputs a specific pattern that is not included in the external device data, as shown in FIG.

This specific pattern is input to the latch circuit 4 and latched, and the specific pattern is output as shown in FIG. 2(H).

On the other hand, the specific pattern is detected by the specific pattern detection circuit 8, which outputs the clear pulse shown in FIG. 2(F) to the parallel-to-serial converter 5, and
The sending data is cleared as shown in FIG.
The glue chamber internal data such as the error information shown in FIG. 3 (G) and FIG.

In response to this input, the ROM 3 outputs external device data corresponding to this device internal data shown in FIG.

This external device data is latched by the launch circuit 4,
This data shown in FIG. 2 (1-I) is output from the output, and in the parallel-to-serial converter 5 it is converted into a serial signal by the clock shown in FIG. 2 (D). The signals are sequentially output as shown in B in FIG. 2 (J) using the transmission clock shown in FIG.

That is, since the ROM 3 uses its own output to control the input to itself, a processor for this operation is not required, and the circuit scale can be reduced.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the ROM uses its own output to control the input to itself, so a processor for this operation is not required, and the circuit scale can be reduced. There is.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an interface circuit according to an embodiment of the present invention, FIG. 2 is a time chart of waveforms of each part of FIG. 1, and FIG. 3 is an explanatory diagram of the operation of the read-only memory of FIG. 1. In the figure, 1.2 is a counter, 3 is a read-only memory, 4 is a launch circuit, 5 is a parallel-to-serial converter, 6 is a data memory, 7 is a flip-flop, and 8 is a specific pattern detection circuit.

Claims (1)

[Scope of Claims] When converting device internal data to external device data and transmitting it using the start-stop synchronization method, data that exists in the external device data and external device data corresponding to each device internal data in the read-only memory. By writing a specific pattern that does not work, and outputting the specific pattern from the read-only memory, the internal data of the device is input, and this input causes the corresponding data for the external device to be output, and then the specific pattern is output. An interface circuit characterized in that outputs are repeated one after another.