Design of infrared communication circuit based on single chip microcomputer

　　The circuit introduced in this article is a practical circuit used for time calibration and meter reading in time-sharing electricity meters. It is simple and practical. Using the asynchronous communication port of the microcontroller, the infrared light transmitting tube sir-563 and the infrared light receiving IC tube rpm6938 are used to realize the functions of receiving and sending point signals, and the half-duplex two-way communication function can be realized. The communication distance is about 10 meters, and the asynchronous communication baud rate is 1200.

　　Circuit principle : The infrared transmitting circuit is composed of a 4001MOS NOR gate 38kHz oscillator, a serial port transmission control gate circuit and an infrared light emitting tube sir-563 drive output circuit. When the txd terminal of the microcontroller serial port is '0', the infrared light emitting tube emits 38kHz modulated infrared light. When the txd terminal is '1', the transmitting tube does not emit light. See Figure 1. The infrared receiving circuit is an infrared receiving special integrated circuit rpm6938. When receiving 38kHz modulated infrared light, the output terminal of rpm6938 is '0', and it is usually '1'. It can be connected with the RXD terminal of the microcontroller serial port.