JPS61144940A - Malfunction preventing circuit - Google Patents

Abstract

PURPOSE:To prevent identification mistake of a data at a weak electric field by generating an interruption signal disregarding a data from a microcomputer if the microcomputer supplies the data signal possible for an error. CONSTITUTION:Waveform shaping circuits 4, 5 generate L, H output signals when a voltage level of an input signal exceeds threshold voltages A, B (B<A). The voltage B is set higher the worst value of noise level and one of output signal groups of a receiver 2 exceeds the voltage A, all the signal groups are set to a value that they exceeds the voltage B. Outputs of the circuits 4, 5 are led respectively to an interruption terminal and an input terminal of the microcomputer 8. When a demodulated output of the receiver 2 is shown in a waveform (a), a waveform shaping output (b) is obtained and a waveform shaping output (c) is obtained from a terminal 7. Thus, if an output from a terminal 6 is momentarily at a low level, the output signal from the terminal 7 is made as an effective data. Conversely if the output of the terminal 6 is not at an L level even momentarily, the output signal at the terminal 7 is disregarded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device for receiving a data signal carried on a high-frequency signal, and a malfunction prevention method suitable for preventing data signal identification errors in special weak electric fields. Regarding circuits.

[Background of the invention]

Conventionally, in CATV converters etc. that have a data reception function, due to a drop in the output on the transmitting system side or a cable break, etc., the voltage level of the detected waveform of the data signal received by the data receiver inside the CATV converter drops, and the data signal When input to an i-electronic router (hereinafter abbreviated as microcomputer), there is a risk that a data signal of such a level as to be erroneously recognized by the microcomputer may occur due to the above-mentioned reasons. The problems of the prior art will be explained below with reference to FIGS. 5 and 4. FIG. 3 shows a connection diagram in the prior art, and FIG. 4(a) shows the data receiver output waveform in a weak electric field, and FIG. 4(b) shows the output waveform after waveform shaping at 7FT.

In the prior art shown in FIG. 5, the demodulated output of the data receiver is simply waveform-shaped at a threshold voltage of a predetermined level and then transmitted to the subsequent microcomputer. For example, when the signal peak value of the logic rHJ is near the threshold voltage as shown in Figure 4 (α), the information of the logic rHJ is dropped after waveform shaping as shown in Figure 4 (Ch'). There was a drawback to it.

[Purpose of the invention]

It is an object of the present invention to eliminate the above-mentioned drawbacks, and to prevent malfunctions by generating an interrupt signal to ignore the data when a microcontroller supplies a data signal that may be erroneous, thereby preventing data identification errors. The purpose is to provide circuits.

[Summary of the invention]

Original F! A is a device that receives a logic signal carried by a high-frequency carrier wave and performs various controls using the logic signal, and connects a data receiver and the output of the data receiver to a waveform shaping circuit having a threshold voltage A. Through,
Connect to the interrupt request terminal of the microcomputer, and connect the data receiver output to the threshold voltage B (
However, this circuit is characterized in that it is connected to the data input terminal of the microcomputer via another waveform shaping circuit having B<A) to prevent malfunctions due to signal identification errors in weak electric fields.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. A high frequency signal modulated by a data signal is inputted from a modulated data signal input terminal 1, demodulated by a data receiver 2, and the demodulated data signal is outputted from a data signal output terminal 5. After this, the data signal is passed through the waveform shaping circuit 5, which generates a high level H output signal when the voltage level of the input signal exceeds the threshold and hold voltage B, and when the voltage level of the input signal exceeds the threshold voltage input. (However, B<A), the signal is input to a waveform shaping circuit 4 which generates a low level L output signal. The threshold island hold voltage B is
The threshold island hold voltage A is set at a level slightly higher than the predicted worst value (maximum value) of the noise level, and the threshold island hold voltage A is set at a level slightly higher than the predicted worst value (maximum value) of the noise level.
If the voltage exceeds the threshold voltage B, all data signal groups are set to a value that guarantees that the voltage exceeds the threshold island hold voltage B. The output of the waveform shaping circuit 4 is
The output of the waveform shaping circuit 5 is led to a microcomputer data input terminal via its output terminal 7.

Here, for example, if a waveform as shown in FIG. 2 (α) is obtained as the demodulated output of the data receiver 2, a waveform shaped output as shown in FIG. 2 (4) is obtained, and from the output terminal 7 A waveform shaped output of the data signal as shown in FIG. 2(ff)K is obtained. When the output from output terminal 6 momentarily becomes low level,
By receiving an interrupt from the external interrupt terminal of the microcomputer, the data signal output from the output terminal 7 is processed by the microcomputer as valid data.

At this time, since it is guaranteed that all data signals outputted from the output terminal 7 exceed the threshold voltage B, there is no possibility of an error. On the other hand, when the output from the output terminal 6 does not become low level even for a moment, no external interrupt is applied to the microcontroller, and in this case, the data signal output from the output terminal 7 is at the threshold level.
This means that the voltage may be lower than the hold voltage B, and the microcontroller discards the input data as invalid.

Thus, according to the present invention, it is possible to prevent data identification errors in the case of a weak electric field.

〔Effect of the invention〕

According to the present invention, a signal is generated that can ignore data signals that may be erroneously recognized by a microcomputer,
It is effective as a data receiver malfunction prevention circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part of the circuit configuration according to the present invention, and FIG. 2 (cL) is a diagram of the output terminal of the data receiver. FIG. 2 (J) is a waveform diagram at the output terminal of the first waveform shaping circuit, FIG. 2 (C) is a waveform diagram at the output terminal of the second waveform shaping circuit, and FIG. 3 is a waveform diagram at the output terminal of the second waveform shaping circuit. FIG. 4 is a block diagram showing the circuit configuration in the prior art. FIG. 4 is a signal waveform diagram of each part of the circuit configuration in the prior art. FIG. ) is a waveform diagram at the output terminal of the waveform shaping circuit. 1... Input terminal of data receiver 2... Data receiver 5... Output terminal of data receiver 4... Waveform shaping circuit having threshold voltage input 5... Having threshold voltage B Waveform shaping circuit 6...Interrupt signal output terminal 7...Data signal output terminal 8...Micro;

Claims (1)

[Claims] In equipment that receives a logic signal carried by a high-frequency carrier wave and performs various controls using the logic signal, the data receiver and the output of the data receiver are connected to a micro waveform shaping circuit having a threshold voltage A. Connect to the interrupt request terminal of the computer, and set the data receiver output to the threshold voltage B (however, B<A).
1. A malfunction prevention circuit, which is connected to a data input terminal of a microcomputer through another waveform shaping circuit having a waveform shaping circuit, and is characterized in that it prevents malfunctions due to signal identification errors in weak electric fields.