Coding the Raspberry Pi Pico MIDI Controller

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Installing the CircuitPython Library Bundle

We're constantly updating and improving our libraries, so we don't (at this time) ship our CircuitPython boards with the full library bundle. Instead, you can find example code in the guides for your board that depends on external libraries. Some of these libraries may be available from us at Adafruit, some may be written by community members!

Either way, as you start to explore CircuitPython, you'll want to know how to get libraries on board.

You can grab the latest Adafruit CircuitPython Bundle release by clicking the button below.

Once you've finished setting up your Raspberry Pi Pico with CircuitPython, you can add the libraries to the lib folder of the Pico's CIRCUITPY drive which should appear when the board is plugged into your computer via USB. Copy these folders:

  • adafruit_bus_device
  • adafruit_display_shapes
  • adafruit_display_text
  • adafruit_midi
  • adafruit_register

And these files:

  • adafruit_aw9523.mpy
  • adafruit_ssd1327.mpy
  • simpleio.mpy

To the CIRCUITPY flash drive /lib directory (create the directory if it doesn't exist).

Then, you can click on the Download: Project Zip link in the window below to download the code file.

Download Project Bundle
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# SPDX-FileCopyrightText: 2021 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time
import board
import displayio
import terminalio
import adafruit_aw9523
import busio
import adafruit_ssd1327
import digitalio
from adafruit_display_text import label
from adafruit_display_shapes.circle import Circle
from adafruit_display_shapes.rect import Rect
import usb_midi
import adafruit_midi
from adafruit_midi.note_on          import NoteOn
from adafruit_midi.note_off         import NoteOff

displayio.release_displays()

# i2c setup, higher frequency for display refresh
i2c = busio.I2C(board.GP1, board.GP0, frequency=1000000)
#  i2c display setup
display_bus = displayio.I2CDisplay(i2c, device_address=0x3D)
#  i2c AW9523 GPIO expander setup
aw = adafruit_aw9523.AW9523(i2c)
#  MIDI setup as MIDI out device
midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=0)

# display dimensions
WIDTH = 128
HEIGHT = 128
#  display setup
display = adafruit_ssd1327.SSD1327(display_bus, width=WIDTH, height=HEIGHT, brightness=0.01)

#  main display group, shows default GUI menu
splash = displayio.Group()
#  group for circle icons
circle_group = displayio.Group()
#  group for text labels on circles
text_group = displayio.Group()

#  list of circle positions
spots = (
    (16, 16),
    (48, 16),
    (80, 16),
    (112, 16),
    (16, 48),
    (48, 48),
    (80, 48),
    (112, 48),
    (16, 80),
    (48, 80),
    (80, 80),
    (112, 80),
    (16, 112),
    (48, 112),
    (80, 112),
    (112, 112),
    )

#  creating the circles & pulling in positions from spots
for spot in spots:
    circle = Circle(x0=spot[0], y0=spot[1], r=14, fill=0x888888)
    # adding circles to their display group
    circle_group.append(circle)
#  square to show position on menu
rect = Rect(0, 0, 33, 33, fill=None, outline=0x00FF00, stroke=3)

splash.append(circle_group)
splash.append(rect)

#  strings and positions for the MIDI note text labels
texts = [
    {'num': "60", 'pos': (12, 16)},
    {'num': "61", 'pos': (44, 16)},
    {'num': "62", 'pos': (76, 16)},
    {'num': "63", 'pos': (108, 16)},
    {'num': "64", 'pos': (12, 48)},
    {'num': "65", 'pos': (44, 48)},
    {'num': "66", 'pos': (76, 48)},
    {'num': "67", 'pos': (108, 48)},
    {'num': "68", 'pos': (12, 80)},
    {'num': "69", 'pos': (44, 80)},
    {'num': "70", 'pos': (76, 80)},
    {'num': "71", 'pos': (108, 80)},
    {'num': "72", 'pos': (12, 112)},
    {'num': "73", 'pos': (44, 112)},
    {'num': "74", 'pos': (76, 112)},
    {'num': "75", 'pos': (108, 112)},
    ]
text_labels = []

for text in texts:
    text_area = label.Label(terminalio.FONT, text=text['num'], color=0xFFFFFF)
    text_area.x = text['pos'][0]
    text_area.y = text['pos'][1]
    text_labels.append(text_area)
    text_group.append(text_area)
splash.append(text_group)

#  secondary display group, shows large circle when button is selected
big_splash = displayio.Group()
#  large circle to fill display
big_circle = Circle(x0=64, y0=64, r=62, fill=0x888888)
big_splash.append(big_circle)
#  large text to fill circle
big_text = label.Label(terminalio.FONT, text='   ', color=0xFFFFFF)
big_text.x = 43
big_text.y = 62
big_text.scale = 4
big_splash.append(big_text)

#  array for LEDs on AW9523
leds = []
led_pins = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
#  setup to create the AW9523 outputs for LEDs
for led in led_pins:
    led_pin = aw.get_pin(led)
    led_pin.direction = digitalio.Direction.OUTPUT
    leds.append(led_pin)



#  button pins, all pins in order skipping GP15
note_pins = [board.GP7, board.GP8, board.GP9, board.GP10, board.GP11,
             board.GP12, board.GP13, board.GP14, board.GP16, board.GP17,
             board.GP18, board.GP19, board.GP20, board.GP21, board.GP22, board.GP26]

note_buttons = []

for pin in note_pins:
    note_pin = digitalio.DigitalInOut(pin)
    note_pin.direction = digitalio.Direction.INPUT
    note_pin.pull = digitalio.Pull.UP
    note_buttons.append(note_pin)

#  note states
note0_pressed = False
note1_pressed = False
note2_pressed = False
note3_pressed = False
note4_pressed = False
note5_pressed = False
note6_pressed = False
note7_pressed = False
note8_pressed = False
note9_pressed = False
note10_pressed = False
note11_pressed = False
note12_pressed = False
note13_pressed = False
note14_pressed = False
note15_pressed = False
#  array of note states
note_states = [note0_pressed, note1_pressed, note2_pressed, note3_pressed,
               note4_pressed, note5_pressed, note6_pressed, note7_pressed,
               note8_pressed, note9_pressed, note10_pressed, note11_pressed,
               note12_pressed, note13_pressed, note14_pressed, note15_pressed]
#  pins for 5-way switch
select = digitalio.DigitalInOut(board.GP6)
up = digitalio.DigitalInOut(board.GP5)
down = digitalio.DigitalInOut(board.GP4)
left = digitalio.DigitalInOut(board.GP3)
right = digitalio.DigitalInOut(board.GP2)
#  array for 5-way switch
joystick = [select, up, down, left, right]

for joy in joystick:
    joy.direction = digitalio.Direction.INPUT
    joy.pull = digitalio.Pull.UP
#  states for 5-way switch
select_state = None
up_state = None
down_state = None
left_state = None
right_state = None
midi_state = None

#  coordinates for navigating main GUI
select_x = [0, 32, 64, 96]
select_y = [0, 32, 64, 96]

#  y coordinate for 5-way switch navigation
y_pos = 0
#  x coordinate for 5-way switch navigation
x_pos = 0
sub_state = False
#  default midi number
midi_num = 60
#  default MIDI button
button_num = 0
#  default MIDI button position
button_pos = 0
#  check for blinking LED
led_check = None
#  time.monotonic() device
clock = time.monotonic()

#  coordinates for tracking location of 5-way switch
up_scroll = 0
down_scroll = 0
left_scroll = 0
right_scroll = 0
switch_coordinates = [(0, 0), (1, 0), (2, 0), (3, 0),
                      (0, 1), (1, 1), (2, 1), (3, 1),
                      (0, 2), (1, 2), (2, 2), (3, 2),
                      (0, 3), (1, 3), (2, 3), (3, 3)]

#  array of default MIDI notes
midi_notes = [60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75]

#  show main display GUI
display.show(splash)

while True:

    #  debouncing for 5-way switch positions
    if up.value and up_state == "pressed":
        print("Button pressed.")
        up_state = None
    if down.value and down_state == "pressed":
        print("Button pressed.")
        down_state = None
    if left.value and left_state == "pressed":
        print("Button pressed.")
        left_state = None
    if right.value and right_state == "pressed":
        print("Button pressed.")
        right_state = None
    if select.value and select_state == "pressed":
        print("Button pressed.")
        select_state = None

    #  MIDI input
    for i in range(16):
        buttons = note_buttons[i]
        #  if button is pressed...
        if not buttons.value and note_states[i] is False:
            #  send the MIDI note and light up the LED
            midi.send(NoteOn(midi_notes[i], 120))
            note_states[i] = True
            leds[i].value = True
        #  if the button is released...
        if buttons.value and note_states[i] is True:
            #  stop sending the MIDI note and turn off the LED
            midi.send(NoteOff(midi_notes[i], 120))
            note_states[i] = False
            leds[i].value = False

    #  if we're on the main GUI page
    if not sub_state:
        #  if you press up on the 5-way switch...
        if not up.value and up_state is None:
            up_state = "pressed"
            #  track the switch's position
            up_scroll -= 1
            if up_scroll < 0:
                up_scroll = 3
            y_pos = up_scroll
            down_scroll = up_scroll
        #  if you press down on the 5-way switch...
        if not down.value and down_state is None:
            down_state = "pressed"
            #  track the switch's position
            down_scroll += 1
            if down_scroll > 3:
                down_scroll = 0
            y_pos = down_scroll
            up_scroll = down_scroll
        #  if you press left on the 5-way switch...
        if not left.value and left_state is None:
            # print("scroll", down_scroll)
            left_state = "pressed"
            #  track the switch's position
            left_scroll -= 1
            if left_scroll < 0:
                left_scroll = 3
            x_pos = left_scroll
            right_scroll = left_scroll
        #  if you press right on the 5-way switch...
        if not right.value and right_state is None:
            # print("scroll", down_scroll)
            right_state = "pressed"
            #  track the switch's position
            right_scroll += 1
            if right_scroll > 3:
                right_scroll = 0
            x_pos = right_scroll
            left_scroll = right_scroll

        #  update square's position on the GUI
        rect.y = select_y[y_pos]
        rect.x = select_x[x_pos]

        #  update the currently highlighted button on the GUI
        for coords in switch_coordinates:
            if x_pos == coords[0] and y_pos == coords[1]:
                button_pos = switch_coordinates.index(coords)
                #  print(button_pos)
        button_num = text_labels[button_pos].text

        #  if you press select on the 5-way switch...
        if not select.value and select_state is None:
            select_state = "pressed"
            #  grab the selected button's MIDI note
            midi_num = int(button_num)
            #  change into the secondary GUI menu
            sub_state = True

    #  if an arcade button is selected to change the MIDI note...
    if sub_state:
        #  display the secondary GUI menu
        display.show(big_splash)
        #  display the selected button's MIDI note
        big_text.text = str(midi_num)

        #  blink the selected button's LED without pausing the loop
        if (time.monotonic() > (clock + 1)) and led_check is None:
            leds[button_pos].value = True
            led_check = True
            clock = time.monotonic()
        if (time.monotonic() > (clock + 1)) and led_check is True:
            leds[button_pos].value = False
            led_check = None
            clock = time.monotonic()

        #  blocks the MIDI number from being set above 128
        if midi_num >= 128:
            midi_num = 128
        #  blocks the MIDI number from being set below 0
        if midi_num <= 0:
            midi_num = 0

        #  if you press right on the 5-way switch...
        if not right.value and right_state is None:
            #  increase the MIDI number
            midi_num += 1
            right_state = "pressed"
        #  if you press up on the 5-way switch...
        if not up.value and up_state is None:
            #  increase the MIDI number
            midi_num += 1
            up_state = "pressed"
        #  if you press left on the 5-way switch...
        if not left.value and left_state is None:
            #  decrease the MIDI number
            midi_num -= 1
            left_state = "pressed"
        #  if you press down on the 5-way switch...
        if not down.value and down_state is None:
            #  decrease the MIDI number
            midi_num -= 1
            down_state = "pressed"

        #  update arcade button's MIDI note
        #  allows you to check note while you're adjusting it
        midi_notes[button_pos] = midi_num

        #  if you press select on the 5-way switch...
        if not select.value and select_state is None:
            select_state = "pressed"
            #  change back to main menu mode
            sub_state = False
            #  update new MIDI number text label
            text_labels[button_pos].text = str(midi_num)
            #  show main GUI display
            display.show(splash)
            #  turn off blinking LED
            leds[button_pos].value = False
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Make sure you've followed these steps:

  • Loaded all the required library files and directories into the CIRCUITPY /lib directory
  • Copied code.py to the main (root) directory of the CIRCUITPY drive

Your Raspberry Pi Pico CIRCUITPY drive should look like this after you load the libraries and code.py file:

3d_printing_picoCpFiles.png
 Installing CircuitPython CircuitPython Code Walkthrough 

This guide was first published on Mar 10, 2021. It was last updated on Mar 10, 2021.

This page (Coding the Raspberry Pi Pico MIDI Controller) was last updated on Sep 25, 2023.

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