CS245093B1 - Connection of analog-to-digital converter with input of microcomputer - Google Patents

Abstract

The essence of the connection is that the terminals of the information pulses of the analog-to-digital converter are connected via delay circuits to a product element, the output of which is connected to the terminal of the synchronization pulse of the input gate. An analog-to-digital converter of the type C520D or AD2020 can be used in the connection.

Description

The connection of the analog-to-digital converter according to the invention allows synchronous transmission of data from the converter to the microcomputer input gate.

An overview of the applications supplied by the manufacturers shows the use of an analog-to-digital converter in conjunction with a microcomputer. In this connection, the cooperation of the analog-to-digital converter is not synchronized, which, in practical use, may lead to the transfer of incorrect data by the microcomputer.

These previous disadvantages are eliminated by the connection of the analog-to-digital converter with the microcomputer input gate, which is based on the fact that the terminals of the information pulses of the analog-to-digital converter are connected via delay circuits to the product.

The main advantage of the circuitry according to the invention is that it excludes the possibility of receiving invalid data, as was the case with earlier unsynchronized circuitry.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by the accompanying drawing, in which an example of wiring is shown.

The input terminal 1 of the measured voltage is connected to the input of the analog-to-digital converter 2, whose output terminals · D0, D1, D2, D3, LSD, NSD, MSD are connected to the input terminals P1, P2, P3, P4, P5, PB, P7 The gateway 3 of the microcomputer whose output is connected to the system bus 4 of the microcomputer. The terminals LSD, NSD, MSD of the information pulses of the analog-to-digital converter 2 are still connected via the delay circuits 5, 6, 7 to the product member 8, which is output connected to the STB terminal of the synchronization pulse of the input gate 3.

The output data of the A / D converter 2 from the output terminals D0 to D3 is fed directly to the input gate 3 of the microcomputer, as well as the information pulses determining the order of the scanned digit in the present number. The highest digit is fed from the MSD terminal, the lowest from the LSD information pulse terminal. The transmitted digit is addressed by the zero level at one of the three terminals of the MSD, NSD, ·, LSD information pulses. The zero level appears at one of the terminals MSD, NSD, LSD of the information pulses when the analog-to-digital converter has valid data at its output. However, at the beginning of the validity of the data, the remaining terminals of the information pulses also show a short zero pulse, which could cause the digits to be mislabeled in the number. Therefore, the effect of these pulses must be eliminated, which is done by delayed reporting of the validity of the data only after its termination. This delay is performed by the delay circuits 5, 6, 7. A logic product of the signals in the product element 8 at the output of the delay circuits 5, 6, 7 generates a zero synchronization pulse to write the data digits from the A / D converter 2 into the gateway buffer. 3 microcomputers.

The microcomputer then identifies the digits according to the value of the upper 4 bits of the captured data, P4, to P7. The method of identification is shown in Table 1.

TABLE 1

Captured number Digit order

1011 XXXX MSD

1101 XXXX NSD

1110 XXXX LSD, where X is any data value in the range of 0 to 9, as expressed by the BCD code. After taking all three digit values, in order MSD, LSD, NSD, the microcomputer arranges them.

Since the A / D converter has a sufficiently long conversion time, the microcomputer input gate does not need to give the converter a readiness report.

The C52OD or AD2020 analog-to-digital converter can be used in the circuit according to the invention.

Claims (1)

Connection of the analog-to-digital (converter with microcomputer input gate), characterized by the fact that the terminals (LSD, NSD, MSD) of the pulses of the analog-to-digital converter (, 2) are connected via the delayed EXIT circuits (5, 6, 7) to the product. (8), the output of which is coupled to the input gate synchronization pulse terminal (STB) (3).