A polyphonic, multitimbral DDS (Direct Digital Synthesis) library for Raspberry Pi Pico, equipped with a sequencer supporting up to 8 channels.
Demo video: YouTube link
Works with RP2040 and RP2350.
- I²S or PWM audio output
- Available waveforms: NOISE, SQUARE, SAW, TRIANGLE, SINE, WAVE (custom waveform)
- ADSR amp envelope
- Polyphony up to 8 voices, each one with individual waveform, ADSR, and volume settings
- 44.100 kHz default sample rate
- Multitrack sequencer able to start and stop playback of multiple (non-concurrent) sequences
- A note name to pitch map, covering notes from B0 to D#8
- Chiptune-ready!
A full example program is included. Please see example/example.c.
To specify which audio output to use, leave uncommented only one of the two definitions in your CMakeLists.txt
target_compile_definitions(${PROJECT_NAME} PRIVATE
# USE_AUDIO_PWM=1
USE_AUDIO_I2S=1
)The audio quality of the PWM output is greatly inferior to the I²S one. It's also very noisy if unfiltered, and for this reason you might want to pair it with a DAC circuit to smooth the signal. There are several designs that will work, but my research led me to the one I used for Dodepan, which also provides some noise filtering and DC offset removal.
This library is the C port of a C++ demo by Pimoroni, adapted to output audio via I²S or PWM. The original depencency of 'Pico Extras' SDK libraries has been removed and I²S functionality is now provided by a PIO-driven I²S driver based on the work of Ricardo Massaro.
- 2024.01.13 - Initial release