mirror of
https://github.com/ashstrahle/Pi-Pico-ExpressionPedal2Midi.git
synced 2025-12-31 19:49:51 +10:00
97 lines
3.7 KiB
Python
Executable File
97 lines
3.7 KiB
Python
Executable File
################################################################################
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#
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# Pi-Pico-ExpressionPedal2Midi
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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 to write to
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cc = 1 # Target Control Change number - Expression Pedal
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cc_min = 0 # Minimum desired CC output - 0 - 127
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cc_max = 127 # Maximum desired CC output - 0 - 127
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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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# Devices
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led = digitalio.DigitalInOut(board.LED)
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led.direction = digitalio.Direction.OUTPUT
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exp = analogio.AnalogIn(board.GP26) # Expression pedal device on pin 31
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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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# This function translates the expression pedal value to the equivalent CC value
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def translate(exp_val):
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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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# Initialise variables
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offset = 1e-6 # Small offset to avoid log(0) error
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# Set these to reverse thresholds to enable calibration
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exp_min = 65535
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exp_max = offset
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exp_calibration_threshold = int(abs(exp_max - exp_min) * exp_pedal_calibration_percent / 100)
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cc_ratio = 1/(cc_max - cc_min) # Calculate number of possible CC values
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exp_previous = exp.value
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if exp_previous == 0:
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exp_previous = offset
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# main loop
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while True:
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exp_current = exp.value
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if exp_current == 0:
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exp_current = offset
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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) / exp_max > cc_ratio:
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if exp_current > exp_max:
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exp_max = exp_current
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elif exp_current < exp_min:
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exp_min = exp_current
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exp_previous = exp_current
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# Only send midi when calibration threshold has been reached
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if exp_max - exp_min > exp_calibration_threshold:
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led.value = True # Turn led on
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cc_val = translate(exp_current)
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uart_midi.send(ControlChange(cc, cc_val))
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usb_midi.send(ControlChange(cc, cc_val))
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led.value = False # Turn led off
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print("Writing Midi Channel: {}, ControlChange: {}, Value {}. Exp Pedal: cur: {}, min: {}, max: {}".format(
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midi_channel, cc, cc_val, exp_current, exp_min, exp_max)) |