mirror of
https://github.com/ashstrahle/Pi-Pico-ExpressionPedal2Midi.git
synced 2025-12-31 19:49:51 +10:00
97 lines
4.2 KiB
Python
Executable File
97 lines
4.2 KiB
Python
Executable File
################################################################################
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#
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# Pi-Pico-ExpressionPedal2Midi (Multiple Pedals)
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#
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# Using USB midi. Midi messages are sent simultaneoulsy to UART1 and USB.
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# Set desired midi channel, change control, and maximum and minimum values
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#
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# Upon run/power on, move expresson pedal from maximum to minimum to calibrate
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# your pedal. CC commands will immediately start sending once calibrated.
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#
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# Ashley Strahle
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# https://github.com/ashstrahle
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#
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################################################################################
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import sys
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import struct
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import time
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import board
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import busio
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import analogio
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import digitalio
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import math
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import usb_midi
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import adafruit_midi
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from adafruit_midi.timing_clock import TimingClock
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from adafruit_midi.note_on import NoteOn
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from adafruit_midi.note_off import NoteOff
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from adafruit_midi.pitch_bend import PitchBend
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from adafruit_midi.control_change import ControlChange
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# Midi output settings
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midi_channel = 1 # Target midi channel
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# Expression pedal settings
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logarithmic = True # Expression pedal logarithmic or linear. Set to False for linear
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log_base = 100 # This value changes the feel of the log curve
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# Required percentage of expression pedal movement for calibration
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exp_pedal_calibration_percent = 80 # 0 - 100
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# Define expression pedals
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expression_pedals = [
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# Set expression pedal midi control change number, and min/max values
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{"pin": board.GP26, "cc": 1, cc_min: 0, cc_max: 127}, # Pedal 1. Pin 31
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{"pin": board.GP27, "cc": 2, cc_min: 0, cc_max: 127}, # Pedal 2. Pin 32
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{"pin": board.GP28, "cc": 3, cc_min: 0, cc_max: 127} # Peadl 3. Pin 34
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]
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# Devices
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led = digitalio.DigitalInOut(board.LED)
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led.direction = digitalio.Direction.OUTPUT
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uart = busio.UART(tx=board.GP4, rx=board.GP5, baudrate=31250, timeout=0.001) # UART Midi device on pin 6
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uart_midi = adafruit_midi.MIDI(midi_out=uart, out_channel=midi_channel - 1)
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usb_midi = adafruit_midi.MIDI(
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midi_out=usb_midi.ports[1], out_channel=midi_channel - 1)
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# Initialize expression pedals
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exp_values = [analogio.AnalogIn(pedal["pin"]) for pedal in expression_pedals]
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exp_previous = [exp.value for exp in exp_values]
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exp_min = [65535 for _ in expression_pedals]
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exp_max = [1e-6 for _ in expression_pedals]
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exp_calibration_threshold = [int(abs(exp_max[i] - exp_min[i]) * exp_pedal_calibration_percent / 100) for i in range(len(expression_pedals))]
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# This function translates the expression pedal value to the equivalent CC value
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def translate(exp_val, exp_min, exp_max, cc_min, cc_max):
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if logarithmic:
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scaled_val = math.log(exp_val, log_base) # Apply logarithmic scaling
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return int((((scaled_val - math.log(exp_min, log_base)) * (cc_max - cc_min)) / (math.log(exp_max, log_base) - math.log(exp_min, log_base))) + cc_min)
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else:
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return int((((exp_val - exp_min) * (cc_max - cc_min)) / (exp_max - exp_min)) + cc_min)
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# Main loop
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while True:
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for i, exp in enumerate(exp_values):
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exp_current = exp.value
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if exp_current == 0:
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exp_current = 1e-6 # Small offset to avoid log(0) error
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# Only process if the change ratio is greater than the possible number of CC values
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if abs(exp_current - exp_previous[i]) / exp_max[i] > 1/(cc_max[i] - cc_min[i]):
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if exp_current > exp_max[i]:
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exp_max[i] = exp_current
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elif exp_current < exp_min[i]:
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exp_min[i] = exp_current
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exp_previous[i] = exp_current
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# Only send midi when calibration threshold has been reached
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if exp_max[i] - exp_min[i] > exp_calibration_threshold[i]:
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led.value = True # Turn led on
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cc_val = translate(exp_current, exp_min[i], exp_max[i], cc_min[i], cc_max[i])
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uart_midi.send(ControlChange(expression_pedals[i]["cc"], cc_val))
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usb_midi.send(ControlChange(expression_pedals[i]["cc"], cc_val))
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led.value = False # Turn led off
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print("Pedal {}: Writing Midi Channel: {}, ControlChange: {}, Value {}. Exp Pedal: cur: {}, min: {}, max: {}".format(
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i + 1, midi_channel, expression_pedals[i]["cc"], cc_val, exp_current, exp_min[i], exp_max[i]))
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