mirror of
https://github.com/ashstrahle/Pi-Pico-ExpressionPedal2Midi.git
synced 2025-12-31 19:49:51 +10:00
56 lines
2.0 KiB
Python
56 lines
2.0 KiB
Python
import sys
|
|
from machine import ADC, Pin, UART
|
|
import ustruct
|
|
import time
|
|
|
|
# Constants
|
|
ControlChange = 0xb0
|
|
|
|
# Midi settings
|
|
midi_channel = 1 # Target midi channel to write to
|
|
cc = 68 # Target Control Change number - this is for Behringer X32 Matrix 5
|
|
cc_min = 0 # Minimum desired CC output
|
|
cc_max = 97 # Maximum desired CC output (only want fader to go to unity gain - hence not 127)
|
|
|
|
exp_pedal_calibration_percent = 80 # Required percentage of expression pedal movement for calibration
|
|
|
|
# Devices
|
|
exp = machine.ADC(Pin(26)) # Expression pedal device on pin 31
|
|
uart = machine.UART(1, 31250) # UART Midi device on pin 6
|
|
led = machine.Pin(25, Pin.OUT) # Pico onboard led
|
|
|
|
# Initialise variables
|
|
# Set these to reverse thresholds to enable calibration
|
|
exp_min = 65535
|
|
exp_max = 1
|
|
|
|
exp_calibration_threshold = int(abs(exp_max - exp_min) * exp_pedal_calibration_percent/100)
|
|
cc_ratio = 1/(cc_max - cc_min) # Calculate number of possible CC values
|
|
|
|
# This function translates the expression pedal value to the equivalent CC value
|
|
def translate(exp_val):
|
|
ret = int((((exp_val - exp_min) * (cc_max - cc_min)) / (exp_max - exp_min)) + cc_min)
|
|
if ret > 0:
|
|
return ret
|
|
else:
|
|
return 0
|
|
|
|
exp_previous = exp.read_u16()
|
|
while True:
|
|
exp_current = exp.read_u16()
|
|
|
|
# Only process if the change ratio is greater than the possible number of CC values
|
|
if abs(exp_current - exp_previous)/exp_max > cc_ratio:
|
|
if exp_current > exp_max:
|
|
exp_max = exp_current
|
|
elif exp_current < exp_min:
|
|
exp_min = exp_current
|
|
exp_previous = exp_current
|
|
|
|
# Only send midi when calibration threshold has been reached
|
|
if exp_max - exp_min > exp_calibration_threshold:
|
|
led.value(1) # Turn led on
|
|
cc_val = translate(exp_current)
|
|
uart.write(ustruct.pack("bbb",ControlChange + midi_channel - 1,cc,cc_val))
|
|
led.value(0) # Turn led off
|
|
print("Writing Midi Channel: {}, ControlChange: {}, Value {}. Exp Pedal: cur: {}, min: {}, max: {}".format(midi_channel, cc, cc_val, exp_current, exp_min, exp_max)) |