midi_hammer

Raspberry pico firmware for measuring piano key positions, using those measurements to simulate hammer movements, and sending resultant velocity information over usb midi.
See a demo here:
https://youtu.be/tgWXtYCHDI4

Arduino

Uses Earle Philhower's Raspberry Pico Arduino core, using Adafruit TinyUSB for usb midi.
There is code for:

• Reading sensors from multiple mcp3008 or mcp3208
• Sending notes over usb midi

The KeyHammer class encapsulates the logic required to run simulation. It can run in two modes: hammer or pedal. In hammer mode, a hammer is simulated in response to ADC values which are assumed to come from a key (or a foot pedal, for triggering drums). In pedal mode, values are read from ADC and directly turned into midi values, useful for controlling sustain pedal or other parameters.
The latest firmware for powering a digital piano sits in arduino/multi_note_simulation.
Pedal firmware sits in arduino/pedal_unit.

Circuit Python

This was the initial prototype. There is working code for reading two sensors via mcp3008, and sending resultant velocities over usb midi.

Notes to self

Arduino plotting

See here for a good guide: https://diyrobocars.com/2020/05/04/arduino-serial-plotter-the-missing-manual/

to do

• Switch class, for on/off pedal from adc input.
• Test class for simulating ADC with random pauses between movements of key.
• Add initial elapsed time for understanding how much spare time each loop there is.
• Compare pico with ESP32 for speed.
• Vectorize code for speed.
• Test simple averaging of multiple adc speeds to reduce hall sensor noise.
• Calibration code
• Add features to arduino code
  • fix for behaviour of gravity (speed update should be based on mean of last and current speeds)
  • simplify handling of sensorFullyOn < sensorFullyOff (flip signs, as in circuitpy code)