FM stereo receiver module

This project focuses on a simple yet powerful FM stereo tuner module. The core component of the module is RDA5807M, a single-chip broadcast FM stereo tuner that has gained popularity among designers in recent years due to its high level of integration. This integration significantly reduces the need for external components, simplifying circuit design. The RDA5807M supports a wide FM band, covering frequencies from 50 MHz to 115 MHz, making it adaptable to global FM standards.

Additionally, its use of a low-IF digital architecture streamlines the design process by requiring fewer external parts. The inclusion of an AGC (automatic gain control) feature ensures consistent signal reception, even in environments with fluctuating signal strengths.

The chip's digital stereo decoding capabilities deliver high-quality audio output, providing a rich stereo sound experience. Moreover, the energy efficiency of the RDA5807M makes it suitable for portable, battery-powered devices. The I2C control interface allows for easy integration with microcontrollers, enabling straightforward digital control.

This module is designed as a ready-to-use FM receiver solution, emphasizing compactness and ease of integration. It incorporates the RDA5807M IC and the STM8S003F3P MCU, along with the necessary supporting passive components, standard headers for connections, and flexible antenna connectivity options. The module is engineered to connect with commonly available 0.56-inch, 4-digit common cathode LED seven-segment display modules without any soldering.

The compact footprint of the module makes it ideal for projects where space is at a premium. Importantly, its open-source design allows for complete customization and modification.

It provides standard stereo audio output with separate left and right channels. The antenna input options allow for various antenna types, ensuring optimal signal reception. During testing, we utilized a 30 cm long wire as the antenna and successfully received all FM stations clearly.

The tuner module features push switches to perform automatic station scans in both directions. The firmware limits the tuning range of the module to between 87 MHz and 108 MHz. Additionally, it includes digital volume control with 15 levels and a memory manager for storing up to 10 FM radio stations. The current tuner frequency is displayed on the segment display module, and there are two LEDs to indicate stereo reception and memory manager status.

The output level of this receiver module is not sufficient to drive speakers directly. Therefore, to achieve audio output through speakers, this module needs to be paired with a stereo audio amplifier. During testing, we successfully used the commonly available PAM8403 3W class-D audio amplifier with this module.

Power is supplied via a screw terminal, typically requiring a DC power source between 5V and 9V. The dimensions of the module are 72.85 mm x 32.0 mm.

This project is available on GitHub, providing schematics, PCB files, firmware source code, and comprehensive documentation. The hardware design of this project is licensed under CERN-OHL-W, while the firmware is licensed under the terms and conditions of the MIT license. All other resources, including documentation, are released under the Creative Commons Attribution 4.0 International License.