It is not necessary to actually use the SOMO module with the bit-banged serial command interface to select the sound files off the microSD card. The module also supports attachment of three switch closure inputs including RESET, NEXT and PREVIOUS. Using this you can get the controller to play the numbered .AD4 files one at a time in sequence. RESET puts it back to the first file and the others walk you through the sequence in either the forward or reverse sequence.

I chose to use the serial interface method because it allows the random selection of the sound sequence.

Mike Karas