LED display and key detection multiplexing circuit

Abstract

The invention relates to an LED display and key detection multiplexing circuit. One end of a pull-up resistor is connected with a power source end, the other end of the pull-up resistor is connected with one end of a key and one end of an input resistor, the other end of the key is connected with the reference ground, and the other end of the input resistor is connected with a port of a single chip microcomputer; one end of a current-limiting resistor is connected with the port of the single chip microcomputer, the other end of the current-limiting resistor is connected with a collector of an audion; a base of the audion is connected with a base resistor, the other end of the base resistor is connected with the port of the single chip microcomputer, an emitter of the audion is connected with the positive pole of a display device, and the negative pole of the display device is connected with the reference ground; one end of a pull-down resistor is connected with the base of the audion, and the other end of the pull-down resistor is connected with the reference ground. The port of one single chip microcomputer is used for processing LED display and key detection in a multiplexing mode, LED short-circuit failure or interference with the other multiplexing function after key short-circuit failure can be effectively prevented, and the service life of the product is effectively prolonged.

Description

technical field [0001] The invention relates to the technical field of low-voltage signal control circuits, in particular to a multiplexing processing circuit for LED display and button detection commonly used in fields such as small household appliances. Background technique [0002] In modern electronic products, automatic control systems, electronic equipment, household appliances, electronic toys, etc., DC motors have been widely used. The tape recorders, record players, video cameras, electronic computers, etc. that people are familiar with cannot lack DC motors. [0003] In the actual DC motor control circuit, three LEDs are commonly used to indicate the operation, protection, fault and other conditions respectively, and different work and fault codes are indicated by different LED flashing lengths or number combinations. [0004] Often due to the limited resources of the single-chip microcomputer, it is often necessary to multiplex the LED display and key detection f...

AI Technical Summary

Problems solved by technology

[0006] use figure 2 circuit, the LED will also display an error after the button fails (such as a normal short circuit), resulting in false alarms on the display

If the LED fails (such as short circuit), it will cause the button to fail

Moreover, the triode will enter micro-amplification, and the LED will be slightly bright, which will affect the vision

Then, the life of the product is shortened, and it cannot be operated with a disease

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