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The remote controller is composed of infrared receiving and transmitting circuit, signal conditioning circuit, central controller 8031, program and data memory, keyboard and status indication circuit.

The remote control has two states: learning state and control state. When the remote control is in the learning state, every time the user presses a control key, the infrared receiving circuit starts to receive the external infrared signal, and at the same time converts it into an electrical signal, and then undergoes detection, shaping, and amplification, and then the CPU regularly samples it. The binary data of each sampling point is stored in a designated storage unit with 8 bits as a unit for later control of the device.

When the remote control is in the control state, every time the user presses a control key, the CPU reads a series of binary data from the designated storage unit, and outputs serially (the time interval between bits and bits is equal to the time interval during sampling ) To the signal holding circuit, at the same time, the modulation circuit performs signal modulation. After the modulation signal is amplified, it is emitted by the infrared emitting diode, so as to realize the control of the device function corresponding to the key.

1. Principle

An infrared remote control is a device that uses an infrared light-emitting diode and uses infrared light as a carrier to transmit key information to the receiving end. Infrared light is invisible to the human eye, so using an infrared remote control will not affect human vision (you can turn on the mobile phone camera and press the remote control against the camera to see the infrared light emitted by the remote control).

2. Modulation

There are many infrared light sources in daily life environment, such as the sun, candle fire, incandescent lamp, and even our body. These infrared light sources may cause interference to our receiving equipment. In order to shield the interference and only receive valid information, we need to use modulation. Modulation is our method of distinguishing the desired signal from noise. By modulation, we can make infrared light blink at a specific frequency. The infrared receiver will adapt to this frequency, and other noise signals will be ignored. You can think of this flicker as a way to attract the receiver's attention, just as we humans are particularly susceptible to being noticed by yellow lights, even during the day.