Hitachi RAS-5102 inverter air conditioner remote control transmitter circuit diagram

Shown below is the remote control transmitter circuit diagram of Hitachi RAS-5102 inverter air conditioner . The ICl (SMC6214FOY) in the circle is the modulation and encoding integrated circuit for the remote control signal. It is actually also a signal processing chip. The integrated circuit is powered by 3V DC voltage. This circuit is connected to two external crystals Xl and X2. Xl has a lower frequency and is a secondary oscillator. It mainly provides character clock signals for timing and character display circuits. X2 is the main oscillator, which provides the clock for the modulation and encoding circuit, and forms the carrier signal of the remote control data after frequency division.     The leads of @~@ pins and @~@ pins form a key matrix operation keyboard circuit, and operation keys are set at the intersection points of each lead to provide key input signals for IC1. ICI codes according to the key input signal and the data stored in the internal memory, and then modulates the coded signal. The modulated signal is output from the @ pin. After being amplified by the driving transistor Q1, the modulated coded signal is added to the infrared light-emitting diode Dl . At the negative terminal, the power supply 3V is added to the positive terminal of Dl, and Dl emits an infrared light signal.