Audio and video infrared remote control[Copy link]
I. Overview: The HT48R06A-1 single chip is used to form an audio and video signal source converter, which can easily demodulate the infrared coding signal of the transmitter, drive the corresponding indicator light and output hexadecimal signal. After demodulation by the decoding circuit, it drives the electronic switch to complete the signal source conversion function.
The circuit consists of 8 signal source buttons, four hexadecimal output lines, one power control line, and two LED indicators. At the same time, the hexadecimal coded signal is demodulated by a CD4051 to produce the corresponding signal source indicator signal to drive 6 LEDs. The 8 buttons are "POWER", "LOCK", "DVD", "SAT", "VCR", "CATV", "AUX1" and "AUX2". The modulation signal is output by four data lines. One line is demodulated by a CD4051 to drive the LED indicator, and the other line is also demodulated by CD4051 to drive the electronic switch to control the switching of the signal source.
In addition to the transmitter that can control the signal source, the corresponding signal source switching button is also set on the mainboard, so we use a 3x3 simple keyboard. The program can use the scanning query method to determine the state of a certain button, so as to output the corresponding control signal.
The mainboard is also equipped with a power indicator and a LOCK indicator. At the same time, the control voltage of the power supply is also taken from the same output port, making full use of the port resources. The "LOCK" state can lock other function keys except the "POWER" button to prevent misoperation or children's operation.
After the infrared receiving tube receives the control stream, the CPU interprets it and outputs the corresponding signal, which is decoded by the demodulation chip. Here we use the demodulation chip for multi-channel demodulation instead of directly using the I/O port of the microcontroller because the I/O port line of this MCU is insufficient. Of course, you can also choose an MCU with more ports. This depends on the performance-price ratio of the selected solution. Or if there are not many signal sources to be switched, you can also directly use the I/O port to connect to the electronic switch to save hardware expenses. The specific usage plan can be adapted to local conditions and mastered flexibly, as long as it meets the functional requirements.
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