Here's a great demo by Astrophage:
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Download the Project Bundle
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Drag the contents of the uncompressed bundle directory onto your board's CIRCUITPY drive, replacing any existing files or directories with the same names, and adding any new ones that are necessary.
# SPDX-FileCopyrightText: 2023 John Park for Adafruit
#
# SPDX-License-Identifier: MIT
# Hexboard seven key modal note/chord pad for MIDI instruments
# Runs on QT Py RP2040
# (other QT Pys should work, but the BOOT button is handy for initiating configuration)
import time
import board
from digitalio import DigitalInOut, Pull
import keypad
import neopixel
import rainbowio
import usb_midi
import adafruit_midi
from adafruit_midi.note_on import NoteOn
from adafruit_midi.note_off import NoteOff
button = DigitalInOut(board.BUTTON)
button.pull = Pull.UP
num_switches = 7
leds = neopixel.NeoPixel(board.A0, num_switches, brightness=0.7)
leds.fill(rainbowio.colorwheel(5))
leds.show()
# root_picked = False
note = 0
root = 0 # defaults to a C
# lists of modal intervals (relative to root). Customize these if you want other scales/keys
major = (0, 2, 4, 5, 7, 9, 11)
minor = (0, 2, 3, 5, 7, 8, 10)
dorian = (0, 2, 3, 5, 7, 9, 10)
phrygian = (0, 1, 3, 5, 7, 8, 10)
lydian = (0, 2, 4, 6, 7, 9, 11)
mixolydian = (0, 2, 4, 5, 7, 9, 10)
locrian = (0, 1, 3, 5, 6, 8, 10)
modes = []
modes.append(major)
modes.append(minor)
modes.append(dorian)
modes.append(phrygian)
modes.append(lydian)
modes.append(mixolydian)
modes.append(locrian)
octv = 4
mode = 0 # default to major scale
play_chords = True # default to play chords
pre_notes = modes[mode] # initial mapping
keymap = (4, 3, 5, 0, 2, 6, 1) # physical to logical key mapping
# Key chart | logical |Interval chart example
# 6 1 | 6 7 | 9 11
# 5 0 2 | 3 4 5 | 4 5 7
# 4 3 | 0 1 | 0 2
# MIDI Setup
midi_usb_channel = 1 # change this to your desired MIDI out channel, 1-16
midi_usb = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=midi_usb_channel-1)
# Keyswitch setup
keyswitch_pins = (board.A3, board.A2, board.SDA, board.SCL, board.TX, board.RX, board.A1)
keyswitches = keypad.Keys(keyswitch_pins, value_when_pressed=False, pull=True)
def pick_mode():
print("Choose mode...")
mode_picked = False
# pylint: disable=global-statement
global mode
while not mode_picked:
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
mode = keymap.index(keyswitch.key_number) # bottom left key is 0/major
print("Mode is:", mode)
if keyswitch.released:
mode_picked = True
leds.fill(rainbowio.colorwheel(8))
leds.show()
pick_octave()
def pick_octave():
print("Choose octave...")
octave_picked = False
# pylint: disable=global-statement
global octv
while not octave_picked:
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
octv = keymap.index(keyswitch.key_number) # get remapped position, lower left is 0
print("Octave is:", octv)
if keyswitch.released:
octave_picked = True
leds.fill(rainbowio.colorwheel(16))
pick_root()
def pick_root():# user selects key in which to play
print("Choose root note...")
root_picked = False
# pylint: disable=global-statement
global root
while not root_picked:
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
root = keymap.index(keyswitch.key_number) # get remapped position, lower left is 0
print("ksw:", keyswitch.key_number, "keymap index:", root)
note = pre_notes[root]
print("note:", note)
midi_usb.send(NoteOn(note + (12*octv), 120))
root_notes.clear()
# pylint: disable=redefined-outer-name
for mode_interval in range(num_switches):
root_notes.append(modes[mode][mode_interval] + note)
print("root note intervals:", root_notes)
if keyswitch.released:
note = pre_notes[root]
midi_usb.send(NoteOff(note + (12*octv), 0))
root_picked = True
leds.fill(0x0)
leds[3] = rainbowio.colorwheel(12)
leds[4] = rainbowio.colorwheel(5)
leds.show()
pick_chords()
def pick_chords():
print("Choose chords vs. single notes...")
chords_picked = False
# pylint: disable=global-statement
global play_chords
while not chords_picked:
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
if keyswitch.key_number == 4:
play_chords = True
print("Chords are on")
chords_picked = True
playback_led_colors()
if keyswitch.key_number == 3:
play_chords = False
print("Chords are off")
chords_picked = True
playback_led_colors()
# create the interval list based on root key and mode that's been picked in variable
root_notes = []
for mode_interval in range(num_switches):
root_notes.append(modes[mode][mode_interval] + note)
print("---Hexpad---")
print("\nRoot note intervals:", root_notes)
key_colors = (18, 10, 18, 26, 26, 18, 10)
def playback_led_colors():
for i in range(num_switches):
leds[i]=(rainbowio.colorwheel(key_colors[i]))
leds.show()
time.sleep(0.1)
playback_led_colors()
# MIDI Note Message Functions
def send_note_on(note_num):
if play_chords is True:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOn(note_num, 120))
midi_usb.send(NoteOn(note_num + modes[mode][2], 80))
midi_usb.send(NoteOn(note_num + modes[mode][4], 60))
midi_usb.send(NoteOn(note_num+12, 80))
else:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOn(note_num, 120))
def send_note_off(note_num):
if play_chords is True:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOff(note_num, 0))
midi_usb.send(NoteOff(note_num + modes[mode][2], 0))
midi_usb.send(NoteOff(note_num + modes[mode][4], 0))
midi_usb.send(NoteOff(note_num+12, 0))
else:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOff(note_num, 0))
def send_midi_panic():
for x in range(128):
midi_usb.send(NoteOff(x, 0))
def launch_config():
print("-launching config-")
send_midi_panic()
leds.fill(rainbowio.colorwheel(5))
leds.show()
pick_mode()
send_midi_panic() # turn off any stuck notes at startup
while True:
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
keyswitch_number=keyswitch.key_number
if keyswitch.pressed:
note_picked = keymap.index(keyswitch.key_number)
send_note_on(note_picked)
leds[keyswitch_number]=(rainbowio.colorwheel(10))
leds.show()
if keyswitch.released:
note_picked = keymap.index(keyswitch.key_number)
send_note_off(note_picked)
leds[keyswitch_number]=(rainbowio.colorwheel(key_colors[keyswitch_number]))
leds.show()
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
You may already have a favorite software synth, and chances are it'll work with the Hexpad. In case you don't have one already picked out, here are some good ones to try.
iOS (with an OTG USB to Lightning adapter)
Chrome Web Browser
Linux / Windows / mac os
Once you've picked a synth, plug in your Hexpad and get playing!
Plug in a known good power and data USB-C cable to the Hexpad, and plug the other end into your computer or OTG adapter.
MIDI Device
It's very likely the synth will recognize it immediately, but if not, check the preferences and choose the "QT Py RP2040" MIDI device.
Now, press any keys or combinations to play! All notes will be "good" notes because of the scale mode.
If you want to change the mode, octave, root note, and the choice of modal chords vs. single notes, simply press the Boot button on the QT Py. You'll see a prompt for each step in a serial REPL window, but you can also do these steps without it.
These are the configuration steps and corresponding keys:
Mode Map
- key 0 = major
- key 1 = minor
- key 2 = dorian
- key 3 = phrygian
- key 4 = lydian
- key 5 = mixolydian
- key 6 = locrian
You can create other modes by editing the code.py file directly.
Octave Map
The octaves correspond to the key numbers shown here. 4 or 3 are good places to start, but you can play super low or ultra high if you like!
Root Map
The key-to-note assignment will vary during play depending on the root note and mode. While in configuration mode on the root selection step, these are the assignments.
You can adjust these in code if you want sharps/flats.
Chord Mode
For polyphonic chord playback, press the chord key. For monophonic note playback, press the single key.
import time import board from digitalio import DigitalInOut, Pull import keypad import neopixel import rainbowio import usb_midi import adafruit_midi from adafruit_midi.note_on import NoteOn from adafruit_midi.note_off import NoteOff
Boot Button
The Boot button on the QT Py RP2040 can be used as a user button. You'll set it up so that it can be used later to initiate the configuration process.
button = DigitalInOut(board.BUTTON) button.pull = Pull.UP
num_switches = 7 leds = neopixel.NeoPixel(board.A0, num_switches, brightness=0.7) leds.fill(rainbowio.colorwheel(5)) leds.show()
Note and Mode Variables
A number of variables and lists are set up to store the note values and intervals of the scale modes.
note = 0 root = 0 # defaults to a C # lists of modal intervals (relative to root). Customize these if you want other scales/keys major = (0, 2, 4, 5, 7, 9, 11) minor = (0, 2, 3, 5, 7, 8, 10) dorian = (0, 2, 3, 5, 7, 9, 10) phrygian = (0, 1, 3, 5, 7, 8, 10) lydian = (0, 2, 4, 6, 7, 9, 11) mixolydian = (0, 2, 4, 5, 7, 9, 10) locrian = (0, 1, 3, 5, 6, 8, 10) modes = [] modes.append(major) modes.append(minor) modes.append(dorian) modes.append(phrygian) modes.append(lydian) modes.append(mixolydian) modes.append(locrian) octv = 4 mode = 0 # default to major scale play_chords = True # default to play chords pre_notes = modes[mode] # initial mapping keymap = (4, 3, 5, 0, 2, 6, 1) # physical to logical key mapping
midi_usb_channel = 1 # change this to your desired MIDI out channel, 1-16 midi_usb = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=midi_usb_channel-1)
Keyswitch Setup
The keyswitches are set up using the keypad library, with their GPIO pins selected in order so the physical placement will correspond to the logical key assignments 0-6.
keyswitch_pins = (board.A3, board.A2, board.SDA, board.SCL, board.TX, board.RX, board.A1) keyswitches = keypad.Keys(keyswitch_pins, value_when_pressed=False, pull=True)
Configuration Functions
These functions are used during optional configuration (initiated by the user by pressing the Boot button).
Note the use of while not mode_picked (and others) to have the code wait for the user to press a button.
def pick_mode():
print("Choose mode...")
mode_picked = False
# pylint: disable=global-statement
global mode
while not mode_picked:
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
mode = keymap.index(keyswitch.key_number) # bottom left key is 0/major
print("Mode is:", mode)
if keyswitch.released:
mode_picked = True
leds.fill(rainbowio.colorwheel(8))
leds.show()
pick_octave()
def pick_octave():
print("Choose octave...")
octave_picked = False
# pylint: disable=global-statement
global octv
while not octave_picked:
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
octv = keymap.index(keyswitch.key_number) # get remapped position, lower left is 0
print("Octave is:", octv)
if keyswitch.released:
octave_picked = True
leds.fill(rainbowio.colorwheel(16))
pick_root()
def pick_root():# user selects key in which to play
print("Choose root note...")
root_picked = False
# pylint: disable=global-statement
global root
while not root_picked:
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
root = keymap.index(keyswitch.key_number) # get remapped position, lower left is 0
print("ksw:", keyswitch.key_number, "keymap index:", root)
note = pre_notes[root]
print("note:", note)
midi_usb.send(NoteOn(note + (12*octv), 120))
root_notes.clear()
# pylint: disable=redefined-outer-name
for mode_interval in range(num_switches):
root_notes.append(modes[mode][mode_interval] + note)
print("root note intervals:", root_notes)
if keyswitch.released:
note = pre_notes[root]
midi_usb.send(NoteOff(note + (12*octv), 0))
root_picked = True
leds.fill(0x0)
leds[3] = rainbowio.colorwheel(12)
leds[4] = rainbowio.colorwheel(5)
leds.show()
pick_chords()
def pick_chords():
print("Choose chords vs. single notes...")
chords_picked = False
# pylint: disable=global-statement
global play_chords
while not chords_picked:
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
# pylint: disable=redefined-outer-name
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
if keyswitch.pressed:
if keyswitch.key_number == 4:
play_chords = True
print("Chords are on")
chords_picked = True
playback_led_colors()
if keyswitch.key_number == 3:
play_chords = False
print("Chords are off")
chords_picked = True
playback_led_colors()
def launch_config():
print("-launching config-")
send_midi_panic()
leds.fill(rainbowio.colorwheel(5))
leds.show()
pick_mode()
root_notes = []
for mode_interval in range(num_switches):
root_notes.append(modes[mode][mode_interval] + note)
LED Colors
These are the color assignments per NeoPixel, all specified as values in the rainbowio.colorwheel.
They are all set when the Hexpad is in playback mode (at start and after configuration) with the playback_led_colors() function.
key_colors = (18, 10, 18, 26, 26, 18, 10)
def playback_led_colors():
for i in range(num_switches):
leds[i]=(rainbowio.colorwheel(key_colors[i]))
leds.show()
time.sleep(0.1)
Note Functions
These functions are used for playing notes/chords as well as sending MIDI panic at reset to turn off all notes.
def send_note_on(note_num):
if play_chords is True:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOn(note_num, 120))
midi_usb.send(NoteOn(note_num + modes[mode][2], 80))
midi_usb.send(NoteOn(note_num + modes[mode][4], 60))
midi_usb.send(NoteOn(note_num+12, 80))
else:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOn(note_num, 120))
def send_note_off(note_num):
if play_chords is True:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOff(note_num, 0))
midi_usb.send(NoteOff(note_num + modes[mode][2], 0))
midi_usb.send(NoteOff(note_num + modes[mode][4], 0))
midi_usb.send(NoteOff(note_num+12, 0))
else:
note_num = root_notes[note_num] + (12*octv)
midi_usb.send(NoteOff(note, 0))
def send_midi_panic():
for x in range(128):
midi_usb.send(NoteOff(x, 0))
Main Loop
The program checks for keyswitch events and plays/releases the corresponding notes. You can press multiple keys to send chords and even "chords of chords".
The main loop also checks for the boot button to be pressed to launch configuration.
while True:
keyswitch = keyswitches.events.get() # check for key events
if keyswitch:
keyswitch_number=keyswitch.key_number
if keyswitch.pressed:
note_picked = keymap.index(keyswitch.key_number)
send_note_on(note_picked)
leds[keyswitch_number]=(rainbowio.colorwheel(10))
leds.show()
if keyswitch.released:
note_picked = keymap.index(keyswitch.key_number)
send_note_off(note_picked)
leds[keyswitch_number]=(rainbowio.colorwheel(key_colors[keyswitch_number]))
leds.show()
if button.value is False: # pressed
launch_config()
time.sleep(0.1)
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