Presentation

The Aecho is a very simple-to-use MP3 decoder module, based on the STA013 MP3 decoder from STMicroelectronics, the CS4334 audio DAC from Cirrus Logic and the LM4811 stereo headphone amplifier from Texas Instruments.

The module includes a standard 3.5mm stereo audio connector for connecting headphones or speakers.
Also included is a 'raw audio output' (direct output from the DAC) for line-level interfacing. The module is both breadboard-friendly and production-ready. With it anyone can add MP3 support to any project, whether for sounds effects or music.

Interfacing

The module requires 5V to 6V DC power.
Other than that, I2C is used for initialization and control of the decoder, MP3 data is to be shifted on a clocked serial line whenever a 'request' line is asserted by the module (indicating more MP3 data is required).
Finally, the headphone amplifier is controlled using a clocked volume up/down signal.

On the output side:
- 3.5mm stereo jack
- line-level stereo header

Hardware

Schematic and board files are available in the Dooba Hardware collection.

Software

Libraries are provided as part of the Dooba Firmware SDK to control all parts of the module:
- sta013 (decoder chip) for MP3 decoding
- lm4811 (headphone amp. chip) for volume control