USB Audio

USB audio output for Music Thing Modular Workshop Computer

48kHz 16-bit stereo input through USB

12-bit output through both audio out jacks.

Main knob controls volume:

• Knob at 12 o'clock is the default value (0dB amplification).
• This volume and quieter will not introduce clipping
• Louder volumes may clip but could be useful for boosting quiet sources

Heavily based on the Pico-USB-Audio project project by Tim Tierney, with modifications only to:

• use MTM Computer DAC and knob
• to convert to 48kHz stereo.

Compiling from source

The source is in C, using the Raspberry Pi Pico SDK. To compile:

1. Copy the custom board definition mtm_computer_16mb.h to <path_to_pico_sdk>/src/boards/include/boards/.

2. Set up the environment variable defining the path to the Pico SDK, e.g.: export PICO_SDK_PATH=<path_to_pico_sdk> or equivalent for your shell.

3. Change to 06_usb_audio/ directory

4. Make and build in the usual way for the Pico SDK:

   mkdir build cd build cmake .. make

(The custom board definition defines #define PICO_XOSC_STARTUP_DELAY_MULTIPLIER 64, often needed for the RP2040 to startup).

This code is a modification of the Pico-USB-Audio project by Tim Tierney

Adapted for Music Thing Modular Workshop Computer by Chris Johnson