The Sound Module-II or the SOMO-II is a small and efficient audio module from 4D Systems that is able to play .mp3 or .wma audio files in the convenience of accessing it within a microSD card or a USB Flash drive (by using external components).

The aim of this project is to showcase the basic functions of the SOMO-II Audio Module such as the Play, Pause/Stop, Next, Previous and the Volume controls. The equalizer widget was used for aesthetic purposes. Users can observe the codes are specific byte commands to each function.

Users can easily integrate the SOMO-II audio module to their existing projects and improve its functionality.

How it works



  • 1 4DUino Module
  • 1 SOMO-II Module
  • Jumper wires
  • 1 bread board
  • 1 4ohm 3 watt Speaker


Step 1: Build

Build the circuit as shown in the following diagram and schematic.fritzing

Step 2: Program

Workshop 4 – 4Duino Extended Graphics environment is used to program this project. (The same could be implemented in the latest Arduino IDE)

This project requires the Arduino IDE to be installed as Workshop calls the Arduino IDE for compiling the Arduino sketches. The Arduino IDE however is not required to be opened or modified to program the 4Duino.

Open this file using Workshop 4.


Note: You can download the code here.

Step3: Comms Port

Connect the 4Duino to the PC using µUSB cable.

Then navigate to the Comms tab and select the Comms port to which the 4Duino connected.


Step4: Compile and Upload

Finally, go back to “Home” tab and now click on the “Comp’nLoad” button.


The Workshop 4 IDE will prompt you to insert a µSD card to the PC in order to save the widget images. Insert µSD card, select the appropriate drive and press button “OK”.


If the µSD card has the widget images you can click button “No Thanks”.

Step 5: Insert µSD card

After uploading the program in to the 4Duino, it will try to mount the µSD card. If the µSD card is not present it will prints an error message.

All you need to do is insert the µSD card you saved the image files into the 4Duino.




In the left image, after loading the LCD Screen, the PLAY button is pressed, Track 1 is playing. Note that the slider volume was not moved, the initial volume 15 was used. In the right image, the STOP button was pressed, no audio will play, when PLAY is pressed, it will repeat the track from the start.