JPS59133619A - Data protecting device - Google Patents

Abstract

PURPOSE:To eliminate completely the occurrence of errors in data transmission at the power-on/off time, by using two kinds of DC power sources whose rise and fall are different from each other and controlling data on a data transmission line by the output of a comparator which detects the potential differential difference between DC power sources. CONSTITUTION:The output of a comparator 319 and output terminals of a microcomputer 320 are connected by diodes 313-316; and when the output of the comparator 319 is in the low level, the output of the computer 320 is fixed to the low level also. Consequently, even if abnormal data is generated from the computer 320 at the power-on time, miss data is not transmitted. The computer 320 is set to the low level by the comparator 319 until the comparator 319 becomes the low level after power failure. Therefore, data is not transmitted. Consequently, the transmission miss of the computer 320 at the power-on time or due to a momentary power failure or the like is eliminated completely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a data protection device in a data transmission device using a microcomputer or the like.

Conventional configurations and their problems In recent years, as devices have become more sophisticated, methods using digital control using microcomputers and the like have come to be increasingly used to control them. Particularly in digital transmission circuits, there is a problem in that data to be transmitted becomes erroneous data due to instantaneous power outage or the like. There have been many methods to deal with this problem, one of which will be explained below. FIG. 1 shows a configuration diagram of a conventional data protection device for a data transmission circuit. In FIG. 1, 13 is a reset terminal of a microcomputer 18, 12 is a power supply terminal of the microcomputer 18, and 17 is a microcomputer 18 ground terminals, 1
8 indicates a microcomputer. In addition, 11 is a diode for backflow prevention, 16 is a capacitor for power failure protection, and 14
．． 15 is a data control output terminal of the microcomputer 18 for determining the reset time of the microcomputer 18. The operation of the conventional data protection device for the data transmission circuit configured as described above will be explained.-0 First, in the circuit shown in FIG. 1, the input terminal 1a.

Let us consider the moment when power is supplied to 1b. The current is applied to the power supply terminal 12 of the microcomputer 18 through the diode 11, and is applied to the microcomputer 1-day reset terminal 13 through the time constant circuit including the resistor 14 and capacitor 16.

In addition, the power failure protection capacitor 16 is also charged.

A timing diagram of these operations is shown in FIG. 2. In FIG. 2, 21 is the voltage waveform of the power supply terminal 12 of the microcomputer 18, and 22 is the voltage waveform of the microcomputer 18.
This is the voltage waveform of the reset terminal 13 of . The microcomputer 18 operates during the period from when power is supplied until it reaches the operating voltage v1 (1 between 23 and 24 in FIG. 2).
) only so that the command is not executed. Next, consider a case where the power supply to the microcomputer 18 is stopped due to a momentary power outage or the like. In this case, since electric charge is stored in the power failure protection capacitor 16, the capacitor 16
A current flows into the power supply terminal 12 of the microcomputer 18 and the charge in the capacitor 16 is transferred to the microcomputer 1.
The command is held until the lowest possible voltage is reached to operate the 8. The diode 11 is a backflow prevention diode inserted to prevent this current from flowing to the power supply side 1a.

However, in the above configuration, if an element with a large current consumption such as an N-MOS is used in the microcomputer 18, the power failure protection capacitor 16 [with a large capacity] is not required. There is a problem in that pulses other than data are often outputted to the output terminals 10 to 1f of the microcomputer 18 near v1 of the microcomputer 18, resulting in erroneous data being transmitted.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a data protection device that can prevent errors in data transmission from occurring when the data transmission circuit is powered on or during instantaneous power outages. That is. - Structure of the Invention The present invention includes first and second DC power supplies with different voltages, and a comparator that detects the potential difference caused by the rise or fall of both power sources when they are turned on or off. The data protection device for the data transmission circuit is configured to control the data in the data transmission circuit by connecting the output of the comparator to the output terminal of the data transmission circuit.

Description of examples Figure 3 shows a microcontroller in an embodiment of the present invention. This shows the computer's data protection device.

In FIG. 3, 301, 302, and 307 are resistors and capacitors forming a differential circuit, and the connection point between the resistor 30.7 and the capacitor 302 is connected to the inverting input terminal 309 of the comparator 319.

Resistor 305 and capacitor 306 determine the discharge time constant;
A capacitor 306 is charged by a diode 304 . The discharge current flows through the diode 303 to the comparator 3.
19 appearing at the inverting input terminal 309 of the comparator 31
The normal rotation input terminal 308 of 9 is the microcomputer 32
0 control terminal 317. 310 is a power supply terminal of the comparator 319, 311 is a ground terminal of the comparator 319,
312 is the output terminal of the comparator 319, and diodes 313 to 3f are connected to the output terminals 30 to 3f of the microcomputer 320.
316. 3a is a power supply terminal for the comparator 319, and 3b is a power supply terminal for the microcomputer 320.

The operation of the data protection device of this embodiment configured as follows will be described below. First, power is supplied to the comparator 319 and the microcomputer 320 with a time constant as shown in FIG. 4 when turned on. In FIG. 4, 401 is a waveform of power supplied to the comparator 319, and 402 is a waveform of power supplied to the microcomputer 320.

The power supplied to the comparator 319 passes through a differentiating circuit composed of resistors 301, 307 and a capacitor 3o2, and appears at the inverting input terminal 309'\ of the comparator 319 as a voltage waveform as shown at 403 in FIG. 402 and 403 in Figure 4
The potential difference V is the difference due to the forward voltage of the diodes 303 and 364. The comparator 31'9 is the difference between 402 and 40 in FIG.
3 voltage waveforms are respectively normal rotation and inversion input terminal 308.3
Added to 09. During the period T2 from when the power is turned on until the input potential difference of the comparator 319 becomes zero, the inverting input of the comparator 319 has a higher potential, so the output of the comparator 319 maintains a low level, and after that, the output is inverted. maintain a high level. 404 in FIG. 4 indicates the waveform of the output of the comparator 319. The output of the comparator 319 and the output terminal of the microcomputer 320 are connected to diodes 313 to 3.
When the output of the comparator 319 is at a low level, the output of the microcomputer 320 is similarly fixed at a low level. Therefore, even if abnormal data is generated from the microcomputer 320 when the power is turned on, the output terminal of the microcomputer 320 is held at a low level by the comparator 319, so that erroneous data will not be transmitted.

Next, let's consider a case where the power supply drops due to a power outage or the like. FIG. 6 shows the voltage waveforms at each terminal in that state. In FIG. 6, 501 is the supply voltage waveform to the comparator 319;
Further, 602 is a power supply waveform to the microcomputer 320. 503 is the inverting input terminal 30 of the comparator 319
9, which is supplied via the diode 303 with a time constant for the charge stored in the capacitor 306 to discharge at the resistor 306. In FIG. 6, at the moment of power failure, the input terminal 308 of the comparator 319
, 309 intersect at A1, the comparator 31
The voltage at the normal input terminal 308 (waveform 602 in FIG. 6) is higher than the voltage at the inverting input terminal 309 (waveform 50 in FIG. 5).
3), the comparator 319 maintains the high level, and changes to the low level after the time T5 has elapsed from point A. A waveform 504 in FIG. 5 shows the output state of the comparator 319. When the comparator 319 is at a low level, the output of the microcomputer 320 is also pulled to a low level as described above, so no data is transmitted.

From the above, after the power supply is turned on, the comparator 319
period until it settles down to a high level (T2 in Figure 4)
During the period from the power outage until the comparator 319 becomes low level (after T3 has passed from point A in FIG. 6), the microcomputer 320 is pulled to low level by the comparator 319. In other words, no fuss data is transmitted from the microcomputer 320 at power-on or power outage. Momentary power outages can be considered in the same way by combining Figures 4 and 6. FIG. 6 shows each voltage waveform during a momentary power outage. 601 is the power supply waveform to the comparator 319, 602 is the power supply waveform to the microcomputer 320, and 603 is the inverting input terminal 30 of the comparator 3190.
9 shows the voltage waveform, and 504 shows the output waveform of the comparator 319.

The period from B to C in FIG. 6 is the momentary power outage time.

Effect of the invention As detailed above, according to the present invention, the rise.

By using two types of DC power supplies with different falling edges and installing a comparator to detect the potential difference between them, we have achieved excellent data transmission that can completely eliminate microcomputer data transmission errors caused by power-on or instantaneous power outages. It has the advantage of realizing a circuit data protection device.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional data protection device for data transmission, Fig. 2 is a voltage waveform diagram of the main parts of the device, and Fig. 3 is a diagram of a data protection device for data transmission showing an embodiment of the present invention. The circuit diagram, Figures 4 to 6, shows the voltage waveforms of the main parts of the device.
04...Diode, 306.307...
... Capacitor, 319 ... Comparator, 320.
...Microcomputer, 313-316...
····diode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 112Figure 5Figure 3Figure 4

Claims (1)

[Claims] The first and second DC power supplies have different voltages, and the first and second DC power supplies have different voltages, and the difference in the time constants of rising and falling times when these power supplies are turned on and off. It has a comparator that detects the potential difference between the second power supply and compares the potential difference between the two power supplies, and is configured to control the data transmission circuit until the data transmission circuit reaches a stable operating region based on the output of the comparator. data protection device.