This is a prototype of a sequencer made in a Raspberry Pi Pico. Particulary, an euclidean sequencer, whose steps can be added/removed uniformely in the grid by rotating the encoder.

For the moment, features are:

• 4 voices
• 16 steps
• Audio output through PWM (optionally I2S)
• MIDI USB note output
• Clock input 5V trigger pulse (ie. used by Korg Volca, etc)
• 16 led using 2 shift registers 74hc595, or NeoPixel display
• Event-based system to hook into seq/UI events, see code.py
• Save up to 16 sequences

If encoder is rotated without holding any button, it changes TEMPO.

Button presses select voices, however if a button a holded and encoder is rotated, they have different actions.

• btn #1: add/remove HITS
• btn #2: add/remove OFFSET
• btn #3: add/remove STEPS
• btn #4: schedule sequence 1-16
  • if encoder button is pressed when btn is held, sequence is saved.

A single encoder press, PLAY/STOP sequence.

• btn #1 + #2: clear pattern
• btn #2 + #3: random pattern

• Porting to Arduino C. Despite CircuitPython is great to play around, it doesn't provide hardware timer interrupts, which is critical to keep tempo consistent. Maybe worth trying plain MicroPython, but C surely is a better idea.
• Add more voices
• Sync out
• MIDI sync in
• Improve RC filter on audio PWM pin (currently, just a 4.7k + 1uF cap)