SOMO-II

SOund MOdule 2 (SOMO-II)

The SOMO-II is a compact audio module capable of playing MP3 files stored on a micro-SD card or, with additional components, a USB 2.0 flash drive. It includes an onboard 16-bit MCU dedicated to hardware audio decoding.

The module supports FAT16 and FAT32 formatted storage devices up to 32 GB, features a 24-bit DAC, and supports all MP3 bit rates (ISO 11172-3 & 13813-3 Layer 3) at sampling rates from 8 kHz to 48 kHz.
Audio files can be placed in the root directory or organised in folders—up to 99 folders with 255 files each. Files are easily transferred to the storage device via PC or laptop, and no special software is needed.
The 16-pin drop-in module occupies minimal board space, making it ideal for any embedded audio application. It includes a mono amplifier capable of driving a 4 Ω / 3 W speaker, plus stereo DAC outputs for headphones or external amplifiers.

SOMO-II offers two operating modes:

• Serial Mode: Uses a simple 2-wire UART interface (TX/RX) for control via serial commands such as play, pause, stop, next, previous, and volume, with CRC check support.
• Key Mode: Allows standalone operation without a microcontroller. It can be controlled with as few as two buttons or more, using resistor-based key inputs.

With only two buttons, a 3.3 V–5 V power source, and a speaker, a compact MP3 player can be built.

In short, the SOMO-II is a flexible, space-saving, and cost-effective embedded audio solution for a wide range of applications.

Information about the module

• Low-cost module for all embedded Audio and Sound applications.
• Supports all MP3 bit rates 11172-3 & ISO1381303 with Samples rates from 8Khz to 48Khz
• 24-bit DAC output, dynamic range supports 90dB, SNR supports 85dB
• SERIAL MODE: Supports a 2-Wire 3.3V TTL UART interface to any microcontroller.
• KEY-MODE: Supports a simple stand-alone operation without a host micro.
• Mono amplified Speaker output, capable of driving a 4ohm speaker at 3 Watts (5V supply).
• Stereo DAC audio output to use with an external amplifier or with headphones.
• On-board micro-SD memory card adaptor for storing audio, voice and music files
• This device supports up to 32GB micro-SD memory cards and both FAT16 and FAT32 file formats.
• Supports up to 32GB USB 2.0 Flash Drive, when used in conjunction with a USB socket (not on board), supporting both FAT16 and FAT32 file formats.
• Compact size measuring only 21.0mm Long x 20.5mm Wide x 11.3mm High.
• Weight ~2g.
• 3.3V to 5.0V DC voltage range (single supply).
• RoHS and CE Compliant.