Smart home infrared remote control circuit design strategy - circuit diagram reading every day (99)

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Smart home refers to the use of advanced computer technology, network communication technology, and integrated wiring technology to organically combine various subsystems related to home life, and make home life more comfortable, safe and effective through overall management. Compared with ordinary homes, smart homes not only have traditional living functions, but also provide comfortable, safe, high-grade and pleasant family living space. They also transform from the original passive static structure to a tool with dynamic intelligence, providing a full range of information interaction functions. To help families and the outside to maintain information exchange, optimize people's lifestyles, help people to effectively arrange time, enhance the safety and comfort of home life, and even rationally control the use of various energy sources.

Infrared transmitting circuit module

In the design of the system, how the signal sent by the single chip is recognized by the infrared transmitting tube, and whether the transmitting tube can normally emit the infrared signal is a key problem to be solved by the transmitting circuit. To emit an infrared signal, an infrared emitting device must be available. Infrared light-emitting diode (LED) is a kind of light-emitting diode that can generate infrared light. At present, the widely used infrared light-emitting diode emits infrared light with a wavelength of about 940 nm. The shape is the same as that of an ordinary light-emitting diode, but the color is different. Common infrared emitting diodes have black and transparent colors. The biggest difference between them and ordinary light-emitting diodes is that the emitted light is invisible light, while ordinary light-emitting diodes emit visible light of various colors. Generally, infrared light-emitting diodes are divided into two types. Structure: One is a remote-controlled emission type infrared light-emitting diode (ie, the infrared-emitting diode used in the most commonly used hand-held remote controller); the other is a close-range emission type infrared light-emitting diode, which combines the emission and reception of infrared light. As one. Since this design implements a home remote control, the first one can be used.

As shown in Figure 4, the system remote control transmission schematic diagram, P1.0 port is the key input port; P2.0 port is the infrared transmission port for outputting 38kHz carrier code, the pulse is amplified by 9013 (NPN) and then output by the infrared transmitting tube The 9th pin is the reset pin of the MCU, and the RC manual reset circuit is used; the 18 and 19 pins are connected to the crystal oscillator.

Figure 4 infrared emission circuit diagram

Infrared receiving circuit module

The general infrared receiving head is mainly composed of an integrated circuit plus a RC component, an infrared receiving tube and a filter light. The circuit design is relatively cumbersome and inconvenient in practical applications. The infrared remote control receiver SM0038 integrates the infrared receiving tube, the preamplifier demodulation is equal to one, no external circuit, small volume, good sealing, high sensitivity, simple application, and the receiving distance of the signal is up to 35 meters with a small power infrared transmitting tube. And the price is low. It has only three pins, namely the positive pole of the power supply, the negative pole of the power supply and the signal output end. Its working voltage is about 5V and the receiving frequency is 38kHz. Its main functions include amplification, frequency selection, demodulation, and most of the required signals. Need to be a signal that has been modulated. So that the circuit is the most simplified, sensitivity and anti-interference are very good, is an ideal device to receive infrared signals. As shown in Figure 5:

Figure 5 SM0038