Typical air conditioner remote control transmission circuit schematic diagram (Hisense air conditioner)

Shown is the remote control transmitting circuit of the air conditioner . The circuit is mainly composed of microprocessor ICl (TMP47C422F), 4 MHz crystal
oscillator 22, 32 kHz crystal oscillator Zl, LED liquid crystal display, thermistor TH, and infrared emission tube LED1 It is composed of LED2, transistors
VI and V2, and operation matrix circuit. The transmitter is powered by two AA batteries with a voltage of 3V.
    The remote control uses a dual clock pulse oscillation circuit, which consists of a 4MHz high-frequency main oscillator composed of crystal 22, capacitors C8 and C9 (capacity 20 pF) and the @ and
0 pins of the microprocessor. The 4 MHz pulse generated by the oscillator The signal is frequency divided to produce a 38 kHz carrier frequency pulse. A 32 kHz (accurate value is 32.768 kHz) low-frequency sub-oscillator is composed of
crystal Z1, capacitors C4 and c5 (capacity 20 pF) and @ and @ pins of the processor.
Its output signal is mainly used for clock circuits and liquid crystal display circuits. use.
    In the key matrix scanning circuit, 9 pins of the microprocessor form a matrix to meet the control requirements of the system. Pins 2J-24 of the microprocessor
are the four output terminals of the scanning pulse generator, which are active at high level; the @~@ pins are the five input terminals of the keying signal encoder, which are active at low level
. 4 output terminals and 5 input terminals form a 4×5 key matrix, which can have 20 function keys. In fact, only 17 function keys are used.
Pins 1l, 12, 13, and 14 of the microprocessor control short-circuit plugs to suit different models of this series. When the remote control is working,
the @~@ pins of the microprocessor output timing scan pulses. The 3V voltage supplies power to the microprocessor through the current limiting resistor, and the @ pin of the microprocessor is connected to the negative pole of the power supply.