FM walkie talkie

This is a FM walkie talkie. It is a project I self-made as an undergraduate. I integrated the receiving and transmitting modules into one unit, with the ATmega328p microcontroller as the core of the system. It controls three peripherals, namely the rda5807m chip, qn8027 chip, and the OLED, through the I2C bus. Additionally, there is a microphone module, a CH340G chip, and two headphone input/output interfaces. Together, they form a complete FM transceiver operating in the frequency range of 88-108MHz. When transmitting single-tone or multi-tone sinusoidal signals (20Hz-20kHz), the demodulated output signal remains undistorted.

The board has two input interfaces: one is a headphone jack for connecting to a computer via a wire, and the other is an active microphone input. These two input ports provide signals to the ALI (left channel) and ARI (right channel) of the qn8027 chip. The chip then transmits the signals through the antenna at the specified frequency. The output port can be connected to headphones, where the rda5807m chip receives the signals at the specified frequency through the antenna and outputs them through LOUT and ROUT. The OLED display shows the transmitted and the received frequencies.