When the infrared remote controller sends data, it modulates the binary data into a series of pulse signals, which are transmitted by the infrared transmitting tube. The infrared carrier is a square wave with a frequency of 38kHz. When the infrared receiving end receives the 38kHz carrier signal, it will output a low level, otherwise it will output a high level, so that the “intermittent” infrared light signal can be demodulated into a continuous square wave signal of a certain period, The original data signal can be recovered after demodulation by 1838 integrated infrared receiver. As shown in Figure 1


Figure 1

The demodulation process of infrared receiver is shown in Figure 2


Figure 2

The demodulated “0” and “1” waveforms and MCU coding are shown in Fig. 3 and Fig. 4


Figure 3


Figure 4


Figure 5

After understanding the infrared receiver demodulation and remote control coding, we can write the coding program according to figure 5. Figure 5 is an actual coding of remote control key 1, which is composed of 9ms low-level 4.5ms high-level start code, 26 bit system code, 8-bit data code, 8-bit data inverse code, 23ms high-level and end code.


Circuit diagram


Physical map





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