153 lines
5.0 KiB
Python
153 lines
5.0 KiB
Python
# SPDX-FileCopyrightText: 2021 Sandy Macdonald
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#
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# SPDX-License-Identifier: MIT
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# A MIDI arpeggiator, with three different styles: up, down, or up-down. BPM and
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# note length are both configurable, and LEDs cycle with the currently-played
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# key/note to give some visual feedback.
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# You'll need to connect Keybow 2040 to a computer running a DAW like Ableton,
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# or other software synth, or to a hardware synth that accepts USB MIDI.
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# Drop the keybow2040.py file into your `lib` folder on your `CIRCUITPY` drive.
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# NOTE! Requires the adafruit_midi CircuitPython library also!
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import time
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import board
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from keybow2040 import Keybow2040
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import usb_midi
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import adafruit_midi
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from adafruit_midi.note_off import NoteOff
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from adafruit_midi.note_on import NoteOn
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# Set up Keybow
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i2c = board.I2C()
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keybow = Keybow2040(i2c)
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keys = keybow.keys
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# Set USB MIDI up on channel 0.
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midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=5)
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# The colour to set the keys when pressed, orange-y.
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rgb = (255, 50, 0)
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# MIDI velocity.
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start_note = 60
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velocity = 100
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# Beats per minute
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bpm = 120
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# Play 16th notes
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note_length = 1/16
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# Assumes BPM is calculated on quarter notes
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note_time = 60 / bpm * (note_length * 4)
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# Arpeggio style:
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# 0 = up
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# 1 = down
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# 2 = up-down
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arp_style = 2
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# Start the arp in a forwards direction (1) if the style is up or up-down, or
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# or backwards (-1) if the style is down.
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if arp_style == 0 or arp_style == 2:
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direction = 1
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elif arp_style == 1:
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direction = -1
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# Keep track of time of last note played and last keys pressed
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last_played = None
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last_pressed = []
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while True:
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# Always remember to call keybow.update()!
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keybow.update()
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# If any keys are pressed, go through shenanigans
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if keybow.any_pressed():
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# Fetch a list of pressed keys
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pressed = keybow.get_pressed()
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# If the keys pressed have changed...
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if pressed != last_pressed:
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# Keys that were pressed, but are no longer
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missing = [k for k in last_pressed if k not in pressed]
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# Any keys that were pressed, but are no longer, turn LED off
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# and send MIDI note off for the respective note.
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for k in missing:
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note = start_note +k
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midi.send(NoteOff(note, 0))
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keys[k].set_led(0, 0, 0)
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# Calculate MIDI note numbers
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notes = [start_note + k for k in pressed]
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last_pressed = pressed
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# If going forward (up or starting up-down), start at 0,
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# otherwise start at the end of the list of notes.
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if arp_style == 0 or arp_style == 2:
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this_note = 0
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elif arp_style == 1:
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this_note = len(notes) - 1
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# Send MIDI note on message for current note and turn LED on
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midi.send(NoteOn(notes[this_note], velocity))
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keys[pressed[this_note]].set_led(*rgb)
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# Update last_played time, set elapsed to 0, and update current and
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# last note indices.
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last_played = time.monotonic()
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elapsed = 0
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last_note = this_note
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this_note += direction
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# If the currently pressed notes are the same as the last loop, then...
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else:
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if notes != []:
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# Check time elapsed since last note played
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elapsed = time.monotonic() - last_played
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# If the note time has elapsed, then...
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if elapsed > note_time:
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# Reset at the end or start of the notes list
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if this_note == len(notes) and direction == 1:
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this_note = 0
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elif this_note < 0:
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this_note = len(notes) - 1
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# Send a MIDI note off for the last note, turn off LED
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midi.send(NoteOff(notes[last_note], 0))
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keys[pressed[last_note]].set_led(0, 0, 0)
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# Send a MIDI note on for the next note, turn on LED
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midi.send(NoteOn(notes[this_note], velocity))
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keys[pressed[this_note]].set_led(*rgb)
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# Update time last_played, make this note last note
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last_played = time.monotonic()
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last_note = this_note
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# For the up-down style, switch direction at either end
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if arp_style == 2 and this_note == len(notes) -1:
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direction = -1
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elif arp_style == 2 and this_note == 0:
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direction = 1
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# Increment note
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this_note += direction
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# If nothing is now pressed, but was last time, then send MIDI note off
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# for every note, and turn all the LEDs off.
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elif len(last_pressed) and keybow.none_pressed():
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for note in range(128):
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midi.send(NoteOff(note, 0))
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for key in keys:
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key.set_led(0, 0, 0)
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# Nothing is pressed, so reset last_pressed list
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last_pressed = [] |