MIDI CircuitPython

Build a custom MIDI instrument using CircuitPython! Use the MIDI FeatherWing and Feather M4 to power your musical projects using the classical 5-PIN DIN jacks. The 128x64 OLED with STEMMA QT makes it easy to add a screen with custom UI. Use potentiometers to change the modulation, key, beat division and modes to create an arrangement of MIDI notes.

UART MIDI

Using the MIDI library for CircuitPython, you can create MIDI notes and control MIDI data. Control synths with MIDI capabilities to create unique setups that does exactly what you want it to. The code is a great example of how to write CircuitPython code with MIDI control. 

Wood & Acrylic Case

You can build a beautiful enclosure using acrylic and wood to make an elegant musical project. Use vinyl and a vinyl cutter to create custom decal graphics for labels. This project includes the vector SVG files and the 3D files.

OLED & DisplayIO

The OLED screen shows the BPM, beat division, key and mode selection. Adjusting potentiometers updates the values on screen in real time. Blinka the CircuitPython mascot nods her head along with the BPM acting as a metronome. This uses the displayio library for CircuitPython to display text, UI elements and animated bitmaps.

Parts List

Monochrome 1.3" 128x64 OLED graphic display - STEMMA QT / Qwiic

PRODUCT ID: 938
These displays are small, only about 1.3" diagonal, but very readable due to the high contrast of an OLED display. This display is made of 128x64 individual white OLED pixels,...
$19.95
IN STOCK

Adafruit MIDI FeatherWing Kit

PRODUCT ID: 4740
Turn your Feather into a song-bird with this musically-enabled FeatherWing that adds MIDI input and output jacks to just about any Feather. You get both input and output DIN-5 MIDI...
$6.95
IN STOCK

Adafruit Feather M4 Express - Featuring ATSAMD51

PRODUCT ID: 3857
It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox-bird (it's half ox,...
$22.95
IN STOCK

FeatherWing Doubler - Prototyping Add-on For All Feather Boards

PRODUCT ID: 2890
This is the FeatherWing Doubler - a prototyping add-on and more for all Feather boards. This is similar to our
$7.50
IN STOCK

Slide Potentiometer with Plastic Knob - 45mm Long

PRODUCT ID: 4272
Slip slidin' away Slip slidin' away You know the nearer your resistance The more you're slip slidin' awayIf you're...
$1.95
IN STOCK
1 x 16mm LED Pushbutton
White Latching On/Off Switch
4 x Slim Metal Knobs
10mm Diameter x 10mm - T18
1 x Panel Mount Extension USB Cable
Micro B Male to Micro B Female
1 x M2.5 Hardware Kit
Black Nylon Standoffs, Screws and Hex Nuts
1 x STEMMA QT Cable
JST SH 4-pin to Premium Male Headers Cable - 150mm Long

The diagram below provides a visual reference for wiring of the components. This diagram was created using the software package Fritzing.

Adafruit Library for Fritzing

Use Adafruit's Fritzing parts library to create circuit diagrams for your projects. Download the library or just grab individual parts. Get the library and parts from GitHub - Adafruit Fritzing Parts.

(click diagram for larger views)

Wired Connections

All parts share common ground and voltage. The ground and voltage lines are wired to the 3V and GND pins on the 128x64 OLED breakout.  The 128x64 OLED breakout uses a STEMMA QT cable wired into the Doubler FeatherWing. All of the signals from the potentiometers are wired into the Doubler FeatherWing.

128x64 OLED breakout

  • SDA to SDA
  • SCL to SCL
  • VCC to 3V
  • GND to GND

Button

  • Ground to GND
  • Signal to D5
  • LED anode to 3V (with 220ohm resistor)
  • LED cathode to GND

Potentiometers

  • Key to pot A1
  • Mode pot A2
  • Beat pot to A3
  • BPM Slider to A4
  • Modulation to A5

Powering

The Adafruit board can be powered via USB or JST using a 3.7v lipo battery.

CAD Assembly

The OLED screen, five potentiometers and LED button are panel mounted to the top panel. A microUSB extension cable is panel mounted to the back panel. The doubler FeatherWing is panel mounted to the bottom panel using M2.5 x 6mm long standoffs.

CNC Milling

Manufacturing models were created for each part and feature stock setups using Fusion 360. Tool paths were generated using the tool library from Bantam Tools.

 

Enclosure Parts Files

The case can optionally be laser cut out of 1/8in thick acrylic. Download the zip file and setup the parts using your preferred software and manufacturing method. Each part is its own SVG file allowing for custom layouts and multi material use.

Decal Files

Additional labels are cut using a vinyl cutter. Vinyl is applied to transfer tape and placed onto acrylic panels. Graphics are included in the SVG zip file.

Design Source File

A STEP file is included and features sketches and solid bodies. The Fusion 360 file features adjustable user parameters and contains tool paths for CNC milling.

CircuitPython is a derivative of MicroPython designed to simplify experimentation and education on low-cost microcontrollers. It makes it easier than ever to get prototyping by requiring no upfront desktop software downloads. Simply copy and edit files on the CIRCUITPY drive to iterate.

The following instructions will show you how to install CircuitPython. If you've already installed CircuitPython but are looking to update it or reinstall it, the same steps work for that as well!

Set up CircuitPython Quick Start!

Follow this quick step-by-step for super-fast Python power :)

Click the link above and download the latest UF2 file.

Download and save it to your desktop (or wherever is handy).

Plug your Feather M4 into your computer using a known-good USB cable.

A lot of people end up using charge-only USB cables and it is very frustrating! So make sure you have a USB cable you know is good for data sync.

Double-click the Reset button next to the USB connector on your board, and you will see the NeoPixel RGB LED turn green. If it turns red, check the USB cable, try another USB port, etc. Note: The little red LED next to the USB connector will pulse red. That's ok!

If double-clicking doesn't work the first time, try again. Sometimes it can take a few tries to get the rhythm right!

You will see a new disk drive appear called FEATHERBOOT.

 

 

 

Drag the adafruit_circuitpython_etc.uf2 file to FEATHERBOOT.

The LED will flash. Then, the FEATHERBOOT drive will disappear and a new disk drive called CIRCUITPY will appear.

That's it, you're done! :)

Further Information

For more detailed info on installing CircuitPython, check out Installing CircuitPython.

As we continue to develop CircuitPython and create new releases, we will stop supporting older releases. Visit https://circuitpython.org/downloads to download the latest version of CircuitPython for your board. You must download the CircuitPython Library Bundle that matches your version of CircuitPython. Please update CircuitPython and then visit https://circuitpython.org/libraries to download the latest Library Bundle.

Each CircuitPython program you run needs to have a lot of information to work. The reason CircuitPython is so simple to use is that most of that information is stored in other files and works in the background. These files are called libraries. Some of them are built into CircuitPython. Others are stored on your CIRCUITPY drive in a folder called lib. Part of what makes CircuitPython so awesome is its ability to store code separately from the firmware itself. Storing code separately from the firmware makes it easier to update both the code you write and the libraries you depend.

Your board may ship with a lib folder already, it's in the base directory of the drive. If not, simply create the folder yourself. When you first install CircuitPython, an empty lib directory will be created for you.

CircuitPython libraries work in the same way as regular Python modules so the Python docs are a great reference for how it all should work. In Python terms, we can place our library files in the lib directory because its part of the Python path by default.

One downside of this approach of separate libraries is that they are not built in. To use them, one needs to copy them to the CIRCUITPY drive before they can be used. Fortunately, we provide a bundle full of our libraries.

Our bundle and releases also feature optimized versions of the libraries with the .mpy file extension. These files take less space on the drive and have a smaller memory footprint as they are loaded.

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.

Note: Match up the bundle version with the version of CircuitPython you are running - 3.x library for running any version of CircuitPython 3, 4.x for running any version of CircuitPython 4, etc. If you mix libraries with major CircuitPython versions, you will most likely get errors due to changes in library interfaces possible during major version changes.

If you need another version, you can also visit the bundle release page which will let you select exactly what version you're looking for, as well as information about changes.

Either way, download the version that matches your CircuitPython firmware version. If you don't know the version, look at the initial prompt in the CircuitPython REPL, which reports the version. For example, if you're running v4.0.1, download the 4.x library bundle. There's also a py bundle which contains the uncompressed python files, you probably don't want that unless you are doing advanced work on libraries.

After downloading the zip, extract its contents. This is usually done by double clicking on the zip. On Mac OSX, it places the file in the same directory as the zip.

Open the bundle folder. Inside you'll find two information files, and two folders. One folder is the lib bundle, and the other folder is the examples bundle.

Now open the lib folder. When you open the folder, you'll see a large number of mpy files and folders

Example Files

All example files from each library are now included in the bundles, as well as an examples-only bundle. These are included for two main reasons:

  • Allow for quick testing of devices.
  • Provide an example base of code, that is easily built upon for individualized purposes.

Copying Libraries to Your Board

First you'll want to create a lib folder on your CIRCUITPY drive. Open the drive, right click, choose the option to create a new folder, and call it lib. Then, open the lib folder you extracted from the downloaded zip. Inside you'll find a number of folders and .mpy files. Find the library you'd like to use, and copy it to the lib folder on CIRCUITPY.

This also applies to example files. They are only supplied as raw .py files, so they may need to be converted to .mpy using the mpy-cross utility if you encounter MemoryErrors. This is discussed in the CircuitPython Essentials Guide. Usage is the same as described above in the Express Boards section. Note: If you do not place examples in a separate folder, you would remove the examples from the import statement.

Example: ImportError Due to Missing Library

If you choose to load libraries as you need them, you may write up code that tries to use a library you haven't yet loaded.  We're going to demonstrate what happens when you try to utilise a library that you don't have loaded on your board, and cover the steps required to resolve the issue.

This demonstration will only return an error if you do not have the required library loaded into the lib folder on your CIRCUITPY drive.

Let's use a modified version of the blinky example.

Download: file
import board
import time
import simpleio

led = simpleio.DigitalOut(board.D13)

while True:
    led.value = True
    time.sleep(0.5)
    led.value = False
    time.sleep(0.5)

Save this file. Nothing happens to your board. Let's check the serial console to see what's going on.

We have an ImportError. It says there is no module named 'simpleio'. That's the one we just included in our code!

Click the link above to download the correct bundle. Extract the lib folder from the downloaded bundle file. Scroll down to find simpleio.mpy. This is the library file we're looking for! Follow the steps above to load an individual library file.

The LED starts blinking again! Let's check the serial console.

No errors! Excellent. You've successfully resolved an ImportError!

If you run into this error in the future, follow along with the steps above and choose the library that matches the one you're missing.

Library Install on Non-Express Boards

If you have a Trinket M0 or Gemma M0, you'll want to follow the same steps in the example above to install libraries as you need them. You don't always need to wait for an ImportError as you probably know what library you added to your code. Simply open the lib folder you downloaded, find the library you need, and drag it to the lib folder on your CIRCUITPY drive.

You may end up running out of space on your Trinket M0 or Gemma M0 even if you only load libraries as you need them. There are a number of steps you can use to try to resolve this issue. You'll find them in the Troubleshooting page in the Learn guides for your board.

Updating CircuitPython Libraries/Examples

Libraries and examples are updated from time to time, and it's important to update the files you have on your CIRCUITPY drive.

To update a single library or example, follow the same steps above. When you drag the library file to your lib folder, it will ask if you want to replace it. Say yes. That's it!

A new library bundle is released every time there's an update to a library. Updates include things like bug fixes and new features. It's important to check in every so often to see if the libraries you're using have been updated.

Once you've finished setting up your Feather M4 Express with CircuitPython, you can add these libraries to the lib folder:

  • adafruit_display_shapes
  • adafruit_display_text
  • adafruit_imageload
  • adafruit_midi
  • adafruit_displayio_ssd1306.mpy
  • neopixel.mpy
  • simpleio.mpy

Then, you can click on the Download: Project Zip link above the code to download the code file and bitmap graphic.

import time
from random import randint
import board
import simpleio
import busio
import terminalio
import neopixel
from digitalio import DigitalInOut, Direction, Pull
from analogio import AnalogIn
import displayio
import adafruit_imageload
from adafruit_display_text import label
import adafruit_displayio_ssd1306
#  uncomment if using USB MIDI
#  import usb_midi
from adafruit_display_shapes.rect import Rect
import adafruit_midi
from adafruit_midi.note_on          import NoteOn
from adafruit_midi.note_off         import NoteOff
from adafruit_midi.control_change   import ControlChange

displayio.release_displays()

oled_reset = board.D9

#turn off on-board neopixel
pixel = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=0)
pixel.fill((0, 0, 0))

# Use for I2C for STEMMA OLED
i2c = board.I2C()
display_bus = displayio.I2CDisplay(i2c, device_address=0x3D, reset=oled_reset)

#  STEMMA OLED dimensions. can have height of 64, but 32 makes text larger
WIDTH = 128
HEIGHT = 32
BORDER = 0

#  blinka sprite indexes
EMPTY = 0
BLINKA_1 = 1
BLINKA_2 = 2

#  setup for STEMMA OLED
display = adafruit_displayio_ssd1306.SSD1306(display_bus, width=WIDTH, height=HEIGHT)

# create the displayio object
splash = displayio.Group(max_size=40)
display.show(splash)

#  text for BPM
bpm_text = "BPM:    "
bpm_text_area = label.Label(
    terminalio.FONT, text=bpm_text, color=0xFFFFFF, x=4, y=6
)
splash.append(bpm_text_area)

bpm_rect = Rect(0, 0, 50, 16, fill=None, outline=0xFFFFFF)
splash.append(bpm_rect)

#  text for key
key_text = "Key:    "
key_text_area = label.Label(
    terminalio.FONT, text=key_text, color=0xFFFFFF, x=4, y=21
)
splash.append(key_text_area)

key_rect = Rect(0, 15, 50, 16, fill=None, outline=0xFFFFFF)
splash.append(key_rect)

#  text for mode
mode_text = "Mode:           "
mode_text_area = label.Label(
    terminalio.FONT, text=mode_text, color=0xFFFFFF, x=54, y=21
)
splash.append(mode_text_area)

mode_rect = Rect(50, 15, 78, 16, fill=None, outline=0xFFFFFF)
splash.append(mode_rect)

#  text for beat division
beat_text = "Div:       "
beat_text_area = label.Label(
    terminalio.FONT, text=beat_text, color=0xFFFFFF, x=54, y=6
)
splash.append(beat_text_area)

beat_rect = Rect(50, 0, 78, 16, fill=None, outline=0xFFFFFF)
splash.append(beat_rect)

#  Blinka sprite setup
blinka, blinka_pal = adafruit_imageload.load("/spritesWhite.bmp",
                                             bitmap=displayio.Bitmap,
                                             palette=displayio.Palette)

#  creates a transparent background for Blinka
blinka_pal.make_transparent(7)
blinka_grid = displayio.TileGrid(blinka, pixel_shader=blinka_pal,
                                 width=1, height=1,
                                 tile_height=16, tile_width=16,
                                 default_tile=EMPTY)
blinka_grid.x = 112
blinka_grid.y = 0

splash.append(blinka_grid)

#  imports MIDI

#  USB MIDI:
#  midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=0)
#  UART MIDI:
midi = adafruit_midi.MIDI(midi_out=busio.UART(board.TX, board.RX, baudrate=31250), out_channel=0)

#  potentiometer pin setup
key_pot = AnalogIn(board.A1)
mode_pot = AnalogIn(board.A2)
beat_pot = AnalogIn(board.A3)
bpm_slider = AnalogIn(board.A4)
mod_pot = AnalogIn(board.A5)

#  run switch setup
run_switch = DigitalInOut(board.D5)
run_switch.direction = Direction.INPUT
run_switch.pull = Pull.UP

#  arrays of notes in each key
key_of_C = [60, 62, 64, 65, 67, 69, 71, 72]
key_of_Csharp = [61, 63, 65, 66, 68, 70, 72, 73]
key_of_D = [62, 64, 66, 67, 69, 71, 73, 74]
key_of_Dsharp = [63, 65, 67, 68, 70, 72, 74, 75]
key_of_E = [64, 66, 68, 69, 71, 73, 75, 76]
key_of_F = [65, 67, 69, 70, 72, 74, 76, 77]
key_of_Fsharp = [66, 68, 70, 71, 73, 75, 77, 78]
key_of_G = [67, 69, 71, 72, 74, 76, 78, 79]
key_of_Gsharp = [68, 70, 72, 73, 75, 77, 79, 80]
key_of_A = [69, 71, 73, 74, 76, 78, 80, 81]
key_of_Asharp = [70, 72, 74, 75, 77, 79, 81, 82]
key_of_B = [71, 73, 75, 76, 78, 80, 82, 83]

#  array of keys
keys = [key_of_C, key_of_Csharp, key_of_D, key_of_Dsharp, key_of_E, key_of_F, key_of_Fsharp,
        key_of_G, key_of_Gsharp, key_of_A, key_of_Asharp, key_of_B]

#  array of note indexes for modes
fifths = [0, 4, 3, 7, 2, 6, 4, 7]
major = [4, 2, 0, 3, 5, 7, 6, 4]
minor = [5, 7, 2, 4, 6, 5, 1, 3]
pedal = [5, 5, 5, 6, 5, 5, 5, 7]

#  defining variables for key name strings
C_name = "C"
Csharp_name = "C#"
D_name = "D"
Dsharp_name = "D#"
E_name = "E"
F_name = "F"
Fsharp_name = "F#"
G_name = "G"
Gsharp_name = "G#"
A_name = "A"
Asharp_name = "A#"
B_name = "B"

#  array of strings for key names for use with the display
key_names = [C_name, Csharp_name, D_name, Dsharp_name, E_name, F_name, Fsharp_name,
             G_name, Gsharp_name, A_name, Asharp_name, B_name]

#  function for reading analog inputs
def val(voltage):
    return voltage.value

#  comparitors for pots' values
mod_val2 = 0
beat_val2 = 0
bpm_val2 = 120
key_val2 = 0
mode_val2 = 0
#  time.monotonic for running the modes
run = 0
#  state for being on/off
run_state = False
#  indexes for modes
r = 0
b = 0
f = 0
p = 0
maj = 0
mi = 0
random = 0
#  mode states
play_pedal = False
play_fifths = False
play_maj = False
play_min = False
play_rando = False
play_scale = True
#  state for random beat division
rando = False
#  comparitors for states
last_r = 0
last_f = 0
last_maj = 0
last_min = 0
last_p = 0
last_random = 0
#  index for random beat division
hit = 0
#  default tempo
tempo = 60
#  beat division
sixteenth = 15 / tempo
eighth = 30 / tempo
quarter = 60 / tempo
half = 120 / tempo
whole = 240 / tempo
#  time.monotonic for blinka animation
slither = 0
#  blinka animation sprite index
g = 1

#  array for random beat division values
rando_div = [240, 120, 60, 30, 15]
#  array of beat division values
beat_division = [whole, half, quarter, eighth, sixteenth]
#  strings for beat division names
beat_division_name = ["1", "1/2", "1/4", "1/8", "1/16", "Random"]

while True:
    #  mapping analog pot values to the different parameters
    #  MIDI modulation 0-127
    mod_val1 = round(simpleio.map_range(val(mod_pot), 0, 65535, 0, 127))
    #  BPM range 60-220
    bpm_val1 = simpleio.map_range(val(bpm_slider), 0, 65535, 60, 220)
    #  6 options for beat division
    beat_val1 = round(simpleio.map_range(val(beat_pot), 0, 65535, 0, 5))
    #  12 options for key selection
    key_val1 = round(simpleio.map_range(val(key_pot), 0, 65535, 0, 11))
    #  6 options for mode selection
    mode_val1 = round(simpleio.map_range(val(mode_pot), 0, 65535, 0, 5))

    #  sending MIDI modulation
    if abs(mod_val1 - mod_val2) > 2:
        #  updates previous value to hold current value
        mod_val2 = mod_val1
        #  MIDI data has to be sent as an integer
        #  this converts the pot data into an int
        modulation = int(mod_val2)
        #  int is stored as a CC message
        modWheel = ControlChange(1, modulation)
        #  CC message is sent
        midi.send(modWheel)
        print(modWheel)
        #  delay to settle MIDI data
        time.sleep(0.001)

    #  sets beat division
    if abs(beat_val1 - beat_val2) > 0:
        #  updates previous value to hold current value
        beat_val2 = beat_val1
        print("beat div is", beat_val2)
        #  updates display
        beat_text_area.text = "Div:%s" % beat_division_name[beat_val2]
        #  sets random beat division state
        if beat_val2 == 5:
            rando = True
        else:
            rando = False
        time.sleep(0.001)

    #  mode selection
    if abs(mode_val1 - mode_val2) > 0:
        #  updates previous value to hold current value
        mode_val2 = mode_val1
        #  scale mode
        if mode_val2 == 0:
            play_scale = True
            play_maj = False
            play_min = False
            play_fifths = False
            play_pedal = False
            play_rando = False
            #  updates display
            mode_text_area.text = "Mode:Scale"
            print("scale")
        #  major triads mode
        if mode_val2 == 1:
            play_scale = False
            play_maj = True
            play_min = False
            play_fifths = False
            play_pedal = False
            play_rando = False
            print("major chords")
            #  updates display
            mode_text_area.text = "Mode:MajorTriads"
        #  minor triads mode
        if mode_val2 == 2:
            play_scale = False
            play_maj = False
            play_min = True
            play_fifths = False
            play_pedal = False
            play_rando = False
            print("minor")
            #  updates display
            mode_text_area.text = "Mode:MinorTriads"
        #  fifths mode
        if mode_val2 == 3:
            play_scale = False
            play_maj = False
            play_min = False
            play_fifths = True
            play_pedal = False
            play_rando = False
            print("fifths")
            #  updates display
            mode_text_area.text = "Mode:Fifths"
        #  pedal tone mode
        if mode_val2 == 4:
            play_scale = False
            play_maj = False
            play_min = False
            play_fifths = False
            play_pedal = True
            play_rando = False
            print("play random")
            #  updates display
            mode_text_area.text = 'Mode:Pedal'
        #  random mode
        if mode_val2 == 5:
            play_scale = False
            play_maj = False
            play_min = False
            play_fifths = False
            play_pedal = False
            play_rando = True
            print("play random")
            #  updates display
            mode_text_area.text = 'Mode:Random'
        time.sleep(0.001)

    #  key selection
    if abs(key_val1 - key_val2) > 0:
        #  updates previous value to hold current value
        key_val2 = key_val1
        #  indexes the notes in each key array
        for k in keys:
            o = keys.index(k)
            octave = keys[o]
        #  updates display
        key_text_area.text = 'Key:%s' % key_names[key_val2]
        print("o is", o)
        time.sleep(0.001)

    #  BPM adjustment
    if abs(bpm_val1 - bpm_val2) > 1:
        #  updates previous value to hold current value
        bpm_val2 = bpm_val1
        #  updates tempo
        tempo = int(bpm_val2)
        #  updates calculations for beat division
        sixteenth = 15 / tempo
        eighth = 30 / tempo
        quarter = 60 / tempo
        half = 120 / tempo
        whole = 240 / tempo
        #  updates array of beat divisions
        beat_division = [whole, half, quarter, eighth, sixteenth]
        #  updates display
        bpm_text_area.text = "BPM:%d" % tempo
        print("tempo is", tempo)
        time.sleep(0.05)

    #  if the run switch is pressed:
    if run_switch.value:
        run_state = True
        #  if random beat division, then beat_division index is randomized with index hit
        if rando:
            divide = beat_division[hit]
        #  if not random, then beat_division is the value of the pot
        else:
            divide = beat_division[beat_val2]
        #  blinka animation in time with BPM and beat division
        #  she will slither every time a note is played
        if (time.monotonic() - slither) >= divide:
            blinka_grid[0] = g
            g += 1
            slither = time.monotonic()
            if g > 2:
                g = 1
        #  holds key index
        octave = keys[key_val2]
        #  fifths mode
        if play_fifths:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  note index from mode, r counts index position
                f = fifths[r]
                #  sends NoteOn
                midi.send(NoteOn(octave[f]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_f]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    last_f = f
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r
                    last_f = f
                    hit = randint(2, 4)
        #  major triad mode
        if play_maj:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  note index from mode, r counts index position
                maj = major[r]
                #  sends NoteOn
                midi.send(NoteOn(octave[maj]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_maj]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    last_maj = maj
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r
                    last_maj = maj
                    hit = randint(2, 4)
        #  minor triad mode
        if play_min:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  note index from mode, r counts index position
                mi = minor[r]
                #  sends NoteOn
                midi.send(NoteOn(octave[mi]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_min]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    last_min = mi
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r
                    last_min = mi
                    hit = randint(2, 4)
        #  pedal tone mode
        if play_pedal:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  note index from mode, r counts index position
                p = pedal[r]
                #  sends NoteOn
                midi.send(NoteOn(octave[p]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_p]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    last_p = p
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r
                    last_p = p
                    hit = randint(2, 4)
        #  random note mode
        if play_rando:
            #  randomizes note indexes in key
            r = randint(0, 7)
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  sends NoteOn
                midi.send(NoteOn(octave[r]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_r]))
                #  print(octave[r])
                run = time.monotonic()
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    r = randint(0, 7)
                    hit = randint(2, 4)
        #  scale mode
        if play_scale:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  sends NoteOn
                midi.send(NoteOn(octave[r]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_r]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r
    if not run_switch.value:
        if run_state:
            all_note_off = ControlChange(123, 0)
            #  CC message is sent
            midi.send(all_note_off)
            run_state = False
            time.sleep(0.001)

    #  delay to settle MIDI data
    time.sleep(0.005)

Bitmap Sprite Sheet

There is a bitmap sprite sheet, spritesWhite.bmp, that is also needed for the code. It will allow for an animation to play on the OLED of Blinka slithering along with the beat of your melodies.

Your Feather M4 CIRCUITPY drive should look like this after you load the libraries, bitmap graphic and code.py file:

Import the Libraries

First, import the libraries. If you're using USB MIDI, then be sure to uncomment import usb_midi.

Download: file
import time
from random import randint
import board
import simpleio
import busio
import terminalio
import neopixel
from digitalio import DigitalInOut, Direction, Pull
from analogio import AnalogIn
import displayio
import adafruit_imageload
from adafruit_display_text import label
import adafruit_displayio_ssd1306
#  uncomment if using USB MIDI
#  import usb_midi
from adafruit_display_shapes.rect import Rect
import adafruit_midi
from adafruit_midi.note_on          import NoteOn
from adafruit_midi.note_off         import NoteOff
from adafruit_midi.control_change   import ControlChange

Turn Off the Onboard NeoPixel

The onboard NeoPixel is turned off so that it doesn't show through the acrylic case.

Download: file
#turn off on-board neopixel
pixel = neopixel.NeoPixel(board.NEOPIXEL, 1, brightness=0)
pixel.fill((0, 0, 0))

Setup the STEMMA OLED

The STEMMA OLED is setup as the display with displayio. It uses I2C for communication. The actual height of the OLED is 64 pixels, but by cutting it in half to 32 pixels, the terminalio font appears larger on the screen.

The sprite indexes for the Blinka sprite that will be animated later in the code are also setup.

Download: file
# Use for I2C for STEMMA OLED
i2c = board.I2C()
display_bus = displayio.I2CDisplay(i2c, device_address=0x3D, reset=oled_reset)

#  STEMMA OLED dimensions. can have height of 64, but 32 makes text larger
WIDTH = 128
HEIGHT = 32
BORDER = 0

#  blinka sprite indexes
EMPTY = 0
BLINKA_1 = 1
BLINKA_2 = 2

#  setup for STEMMA OLED
display = adafruit_displayio_ssd1306.SSD1306(display_bus, width=WIDTH, height=HEIGHT)

# create the displayio object
splash = displayio.Group(max_size=40)
display.show(splash)

Create Text Objects for the OLED

Text objects are setup for the four different parameters that can be controlled with the MIDI Melody Maker: BPM (beats per minute), key, mode and beat division. As you adjust the parameters, their values will be updated live on the screen.

Download: file
#  text for BPM
bpm_text = "BPM:    "
bpm_text_area = label.Label(
    terminalio.FONT, text=bpm_text, color=0xFFFFFF, x=4, y=6
)
splash.append(bpm_text_area)

bpm_rect = Rect(0, 0, 50, 16, fill=None, outline=0xFFFFFF)
splash.append(bpm_rect)

#  text for key
key_text = "Key:    "
key_text_area = label.Label(
    terminalio.FONT, text=key_text, color=0xFFFFFF, x=4, y=21
)
splash.append(key_text_area)

key_rect = Rect(0, 15, 50, 16, fill=None, outline=0xFFFFFF)
splash.append(key_rect)

#  text for mode
mode_text = "Mode:           "
mode_text_area = label.Label(
    terminalio.FONT, text=mode_text, color=0xFFFFFF, x=54, y=21
)
splash.append(mode_text_area)

mode_rect = Rect(50, 15, 78, 16, fill=None, outline=0xFFFFFF)
splash.append(mode_rect)

#  text for beat division
beat_text = "Div:       "
beat_text_area = label.Label(
    terminalio.FONT, text=beat_text, color=0xFFFFFF, x=54, y=6
)
splash.append(beat_text_area)

beat_rect = Rect(50, 0, 78, 16, fill=None, outline=0xFFFFFF)
splash.append(beat_rect)

Setup the Blinka Tilegrid

The Blinka sprite is setup using the adafruit_imageload library. It is setup as a tilegrid so you can iterate through the grid to create an animation of Blinka slithering.

Download: file
#  Blinka sprite setup
blinka, blinka_pal = adafruit_imageload.load("/spritesWhite.bmp",
                                             bitmap=displayio.Bitmap,
                                             palette=displayio.Palette)

#  creates a transparent background for Blinka
blinka_pal.make_transparent(7)
blinka_grid = displayio.TileGrid(blinka, pixel_shader=blinka_pal,
                                 width=1, height=1,
                                 tile_height=16, tile_width=16,
                                 default_tile=EMPTY)
blinka_grid.x = 112
blinka_grid.y = 0

splash.append(blinka_grid)

Setup MIDI

MIDI communication is setup using the adafruit_midi library. You can either use USB MIDI or MIDI over UART with the MIDI FeatherWing's 5-DIN ports.

Download: file
#  imports MIDI

#  USB MIDI:
#  midi = adafruit_midi.MIDI(midi_out=usb_midi.ports[1], out_channel=0)
#  UART MIDI:
midi = adafruit_midi.MIDI(midi_out=busio.UART(board.TX, board.RX, baudrate=31250), out_channel=0)

Setup the Potentiometers and Switch Pins

The pins are setup for the five analog potentiometers and the switch.

Download: file
#  potentiometer pin setup
key_pot = AnalogIn(board.A1)
mode_pot = AnalogIn(board.A2)
beat_pot = AnalogIn(board.A3)
bpm_slider = AnalogIn(board.A4)
mod_pot = AnalogIn(board.A5)

#  run switch setup
run_switch = DigitalInOut(board.D5)
run_switch.direction = Direction.INPUT
run_switch.pull = Pull.UP

Create the MIDI Note Arrays

The MIDI notes for each key (C through B) are setup as arrays. These arrays are then placed into another array called keys so that they can be accessed.

Download: file
#  arrays of notes in each key
key_of_C = [60, 62, 64, 65, 67, 69, 71, 72]
key_of_Csharp = [61, 63, 65, 66, 68, 70, 72, 73]
key_of_D = [62, 64, 66, 67, 69, 71, 73, 74]
key_of_Dsharp = [63, 65, 67, 68, 70, 72, 74, 75]
key_of_E = [64, 66, 68, 69, 71, 73, 75, 76]
key_of_F = [65, 67, 69, 70, 72, 74, 76, 77]
key_of_Fsharp = [66, 68, 70, 71, 73, 75, 77, 78]
key_of_G = [67, 69, 71, 72, 74, 76, 78, 79]
key_of_Gsharp = [68, 70, 72, 73, 75, 77, 79, 80]
key_of_A = [69, 71, 73, 74, 76, 78, 80, 81]
key_of_Asharp = [70, 72, 74, 75, 77, 79, 81, 82]
key_of_B = [71, 73, 75, 76, 78, 80, 82, 83]

#  array of keys
keys = [key_of_C, key_of_Csharp, key_of_D, key_of_Dsharp, key_of_E, key_of_F, key_of_Fsharp,
        key_of_G, key_of_Gsharp, key_of_A, key_of_Asharp, key_of_B]

MIDI Mode Arrays

The different modes call on the array index location for different points in a key. This allows for you to play these different patterns in different keys automatically. These arrays are referencing note indexes ranging from 0 to 7

You can create your own patterns by creating your own arrays of note indexes.

Download: file
#  array of note indexes for modes
fifths = [0, 4, 3, 7, 2, 6, 4, 7]
major = [4, 2, 0, 3, 5, 7, 6, 4]
minor = [5, 7, 2, 4, 6, 5, 1, 3]
pedal = [5, 5, 5, 6, 5, 5, 5, 7]

Key Name Strings for the OLED

Variables are created for the strings of key names. These variables are put into an array called key_names so that they can be displayed on the OLED.

Download: file
#  defining variables for key name strings
C_name = "C"
Csharp_name = "C#"
D_name = "D"
Dsharp_name = "D#"
E_name = "E"
F_name = "F"
Fsharp_name = "F#"
G_name = "G"
Gsharp_name = "G#"
A_name = "A"
Asharp_name = "A#"
B_name = "B"

#  array of strings for key names for use with the display
key_names = [C_name, Csharp_name, D_name, Dsharp_name, E_name, F_name, Fsharp_name,
             G_name, Gsharp_name, A_name, Asharp_name, B_name]

States and Default Array Indexes

States and default array indexes are setup to be referenced later in the loop.

Download: file
#  comparitors for pots' values
mod_val2 = 0
beat_val2 = 0
bpm_val2 = 120
key_val2 = 0
mode_val2 = 0
#  time.monotonic for running the modes
run = 0
#  state for being on/off
run_state = False
#  indexes for modes
r = 0
b = 0
f = 0
p = 0
maj = 0
mi = 0
random = 0
#  mode states
play_pedal = False
play_fifths = False
play_maj = False
play_min = False
play_rando = False
play_scale = True
#  state for random beat division
rando = False
#  comparitors for states
last_r = 0
last_f = 0
last_maj = 0
last_min = 0
last_p = 0
last_random = 0
#  index for random beat division
hit = 0
#  default tempo
tempo = 60
#  beat division
sixteenth = 15 / tempo
eighth = 30 / tempo
quarter = 60 / tempo
half = 120 / tempo
whole = 240 / tempo
#  time.monotonic for blinka animation
slither = 0
#  blinka animation sprite index
g = 1

Beat Division Setup

Arrays are created for beat division. These values allow the MIDI Melody Maker to divide the BPM to play different note values. The possible values are whole notes, half notes, quarter notes, eighth notes and sixteenth notes.

There is also an array of strings so that the beat division can be displayed on the OLED.

Download: file
#  array for random beat division values
rando_div = [240, 120, 60, 30, 15]
#  array of beat division values
beat_division = [whole, half, quarter, eighth, sixteenth]
#  strings for beat division names
beat_division_name = ["1", "1/2", "1/4", "1/8", "1/16", "Random"]

The Loop

Map the Analog Values

The loop begins by mapping the analog values from the potentiometers to the values needed for the different parameters.

Download: file
#  mapping analog pot values to the different parameters
    #  MIDI modulation 0-127
    mod_val1 = round(simpleio.map_range(val(mod_pot), 0, 65535, 0, 127))
    #  BPM range 60-220
    bpm_val1 = simpleio.map_range(val(bpm_slider), 0, 65535, 60, 220)
    #  6 options for beat division
    beat_val1 = round(simpleio.map_range(val(beat_pot), 0, 65535, 0, 5))
    #  12 options for key selection
    key_val1 = round(simpleio.map_range(val(key_pot), 0, 65535, 0, 11))
    #  6 options for mode selection
    mode_val1 = round(simpleio.map_range(val(mode_pot), 0, 65535, 0, 5))

Read the Potentiometers

All of the parameters that are defined by analog potentiometers compare the last reading of the pot to the current reading to define whether the state has changed.

If the state has changed, then values are updated to affect how the MIDI Melody Maker is generating data. The display on the OLED is updated with the new value.

For modulation, a modulation MIDI CC message is sent.

Download: file
#  sending MIDI modulation
    if abs(mod_val1 - mod_val2) > 2:
        #  updates previous value to hold current value
        mod_val2 = mod_val1
        #  MIDI data has to be sent as an integer
        #  this converts the pot data into an int
        modulation = int(mod_val2)
        #  int is stored as a CC message
        modWheel = ControlChange(1, modulation)
        #  CC message is sent
        midi.send(modWheel)
        print(modWheel)
        #  delay to settle MIDI data
        time.sleep(0.001)

Beat Division

For beat division, the text is updated and if the beat division is going to be randomized, the rando state is updated to True. The index for the beat division array is also stored in beat_val2 and is referenced later in the loop.

Download: file
#  sets beat division
    if abs(beat_val1 - beat_val2) > 0:
        #  updates previous value to hold current value
        beat_val2 = beat_val1
        print("beat div is", beat_val2)
        #  updates display
        beat_text_area.text = "Div:%s" % beat_division_name[beat_val2]
        #  sets random beat division state
        if beat_val2 == 5:
            rando = True
        else:
            rando = False
        time.sleep(0.001)

Mode Selection

Mode selection sets the different mode states to True depending on the array index and also updates the OLED's text.

Download: file
#  mode selection
    if abs(mode_val1 - mode_val2) > 0:
        #  updates previous value to hold current value
        mode_val2 = mode_val1
        #  scale mode
        if mode_val2 == 0:
            play_scale = True
            play_maj = False
            play_min = False
            play_fifths = False
            play_pedal = False
            play_rando = False
            #  updates display
            mode_text_area.text = "Mode:Scale"
            print("scale")
        #  major triads mode
        if mode_val2 == 1:
            play_scale = False
            play_maj = True
            play_min = False
            play_fifths = False
            play_pedal = False
            play_rando = False
            print("major chords")
            #  updates display
            mode_text_area.text = "Mode:MajorTriads"
        #  minor triads mode
        if mode_val2 == 2:
            play_scale = False
            play_maj = False
            play_min = True
            play_fifths = False
            play_pedal = False
            play_rando = False
            print("minor")
            #  updates display
            mode_text_area.text = "Mode:MinorTriads"
        #  fifths mode
        if mode_val2 == 3:
            play_scale = False
            play_maj = False
            play_min = False
            play_fifths = True
            play_pedal = False
            play_rando = False
            print("fifths")
            #  updates display
            mode_text_area.text = "Mode:Fifths"
        #  pedal tone mode
        if mode_val2 == 4:
            play_scale = False
            play_maj = False
            play_min = False
            play_fifths = False
            play_pedal = True
            play_rando = False
            print("play random")
            #  updates display
            mode_text_area.text = 'Mode:Pedal'
        #  random mode
        if mode_val2 == 5:
            play_scale = False
            play_maj = False
            play_min = False
            play_fifths = False
            play_pedal = False
            play_rando = True
            print("play random")
            #  updates display
            mode_text_area.text = 'Mode:Random'
        time.sleep(0.001)

Key Selection

Key selection defines which key is selected from the keys array with key_val2 holding the index. octave will be used later in the loop to access the key's MIDI note array. The text for the key's name is also updated for the OLED.

Download: file
#  key selection
    if abs(key_val1 - key_val2) > 0:
        #  updates previous value to hold current value
        key_val2 = key_val1
        #  indexes the notes in each key array
        for k in keys:
            o = keys.index(k)
            octave = keys[o]
        #  updates display
        key_text_area.text = 'Key:%s' % key_names[key_val2]
        print("o is", o)
        time.sleep(0.001)

BPM

BPM is adjusted with the sliding potentiometer. It's value is stored as an integer in tempo. The tempo is divided in the beat division formulas to get the new beat division values. These values are updated in the beat_division array. The BPM's text is updated for the OLED.

Download: file
#  BPM adjustment
    if abs(bpm_val1 - bpm_val2) > 1:
        #  updates previous value to hold current value
        bpm_val2 = bpm_val1
        #  updates tempo
        tempo = int(bpm_val2)
        #  updates calculations for beat division
        sixteenth = 15 / tempo
        eighth = 30 / tempo
        quarter = 60 / tempo
        half = 120 / tempo
        whole = 240 / tempo
        #  updates array of beat divisions
        beat_division = [whole, half, quarter, eighth, sixteenth]
        #  updates display
        bpm_text_area.text = "BPM:%d" % tempo
        print("tempo is", tempo)
        time.sleep(0.05)

Run the MIDI Melody Maker

If the run_switch is pressed, then the run_state is True and the MIDI Melody Maker begins generating MIDI data. 

divide holds the value of the beat division data and determines when a note is played. If the beat division is going to be randomized, then hit (which holds a random integer) acts as the index for beat_division. Otherwise, beat_val2 (which holds the value of the beat division pot) defines the index.

The Blinka animation advances every time a note is played by comparing time.monotonic() to divide

octave allows access to the different keys' MIDI note indexes so that the MIDI notes can be played in the different modes.

Download: file
#  if the run switch is pressed:
    if run_switch.value:
        run_state = True
        #  if random beat division, then beat_division index is randomized with index hit
        if rando:
            divide = beat_division[hit]
        #  if not random, then beat_division is the value of the pot
        else:
            divide = beat_division[beat_val2]
        #  blinka animation in time with BPM and beat division
        #  she will slither every time a note is played
        if (time.monotonic() - slither) >= divide:
            blinka_grid[0] = g
            g += 1
            slither = time.monotonic()
            if g > 2:
                g = 1
        #  holds key index
        octave = keys[key_val2]

Running the Modes: Fifths, Major Triads, Minor Triads and Pedal Tone

The modes with defined arrays (fifths, major triads, minor triads and pedal tone) work in the same way. If their state is True, then time.monotonic() is compared to divide to determine when the next note should be played.

A variable holds the index of the mode's array. That variable is then used as the index for the key's array to be able to play specific notes.

The next note is sent as a MIDI NoteOn message and the previous note is turned off with a MIDI NoteOff message.

Once the end of the array is reached, index positions are reset to the beginning to that the modes can continue playing.

Download: file
#  fifths mode
        if play_fifths:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  note index from mode, r counts index position
                f = fifths[r]
                #  sends NoteOn
                midi.send(NoteOn(octave[f]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_f]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    last_f = f
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r
                    last_f = f
                    hit = randint(2, 4)

Running Scale Mode

For scale mode, rather than referencing an array of defined notes, the keys' array of MIDI note numbers is played in ascending order. r holds the index value and increases by 1. r is reset when it is greater than 7, which is the end of the array.

Download: file
#  scale mode
        if play_scale:
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  sends NoteOn
                midi.send(NoteOn(octave[r]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_r]))
                #  print(octave[r])
                run = time.monotonic()
                #  go to next note
                r += 1
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    hit = randint(2, 4)
                #  resets note index position
                if r > 7:
                    r = 0
                    last_r = r

Running Random Mode

For random mode, the notes are played in a randomized order. In this case, r holds a random integer that is updated every time a note is played. r does not need to be reset since the random integer is constantly updated and is not constrained by an array.

Download: file
#  random note mode
        if play_rando:
            #  randomizes note indexes in key
            r = randint(0, 7)
            #  tracks time divided by the beat division
            if (time.monotonic() - run) >= divide:
                #  sends NoteOn
                midi.send(NoteOn(octave[r]))
                #  turns previous note off
                midi.send(NoteOff(octave[last_r]))
                #  print(octave[r])
                run = time.monotonic()
                #  updates previous value to hold current value
                if r > 0:
                    last_r = r
                    r = randint(0, 7)
                    hit = randint(2, 4)

Stop the MIDI Melody Maker

If you turn off the MIDI Melody Maker by pressing the run_switch, then an all notes off message is sent with MIDI CC message 123. This prevents any notes from accidentally hanging on, which can happen with some DAWs and hardware synths.

run_state is then set to False to reset for the next time you turn the MIDI Melody Maker on.

Download: file
if not run_switch.value:
        if run_state:
            all_note_off = ControlChange(123, 0)
            #  CC message is sent
            midi.send(all_note_off)
            run_state = False
            time.sleep(0.001)

Panel Mounting Parts

Gather up the parts for paneling mounting to the top acrylic.

Install OLED

Remove the protection film from the display. Insert the screws through the top side of the acrylic. Place the OLED breakout over the acrylic and fit the screws through the mounting holes. Install hex nuts onto the threads of the screws to secure.

  • 4x m2.5 x 10mm screw
  • 4x m2.5 hex but

Install Slider

Remove the tip from the slide by pulling it out of the stem. Place onto the bottom side of the top acrylic panel. Line up the mounting holes and insert the screws to secure.

  • 2x M2 x 8mm flat head screw 
If the screw is metal and too long it could short the ground and signal pins! Be careful, this can affect the functionality of the slider.

Install Potentiometer

Panel mount the 10k potentiometer into the holes in the top acrylic panel. The holes are sized to be 7.2mm in diameter.

Install Potentiometers (continued)

Proceed to panel mount the other potentiometers into the top acrylic panel. Use the washer and hex nut that came with the potentiometer to secure.

Install Button

Remove the hex nut washer from the button. Install the button by mounting it to the bigger hole in the top acrylic panel. Use the hex nut washer to secure to the acrylic panel.

Panel Mounted Parts

Take a moment to check the screws and hex nuts are tight and secure. Install the tip back onto the stem of the slider.

Wiring Parts

Follow the circuit diagram and reference the wired connections. Use 10-wire silicone cover ribbon cable to make bundled connections. 

Wired Parts

The parts all share common ground that is wired into the OLED breakout. Wire lengths are moderately sized to allow top and bottom panels to move around. The OLED display uses a STEMMA QT cable for easily plugging into the breakout.

Wiring FeatherWing Doubler

Voltage and ground connections from the OLED breakout are wired into the 3V and GND pins on the FeatherWing Doubler. The signal connections for the potentiometers and button are wired into the accompanying pins on the FeatherWing Doubler.

USB Extension Cable

A panel mounted microUSB extension cable is used to extend the microUSB port on the Feather M4. This cable includes screws for panel mounting to the back acrylic panel. It has been (optionally) resized using silicone ribbon cable to better fit into the enclosure.

FeatherWing Doubler Standoffs

Install the hardware onto the mounting holes on the FeatherWing Doubler.

  • 4x m2.5 x 6mm ff standoff
  • 4x m2.5 x 6mm screw
  • 4x m2.6 x 8mm screw

Secure FeatherWing Doubler to Bottom Panel

Place the FeatherWing Doubler onto the bottom acrylic panel and line up the mounting holes. Insert and fasten screws to secure the FeatherWing Doubler to the bottom acrylic panel.

Feather M4 & MIDI FeatherWing

Insert the Feather M4 and MIDI FeatherWing into the headers of the FeatherWing Doubler. Reference the photo for correct placement.

Panel Mount USB Cable

Place the microUSB cable onto the small hole on the back acrylic panel. Insert and fasten the screws through the panel to secure microUSB cable.

Plug-in USB Cable

Connect the microUSB extension cable to the Feather M4. Double check the orientation of the Feather M4 and MIDI FeatherWing are correct.

Installing Sides

Gather up the acrylic panels to fit into the left and right sides.

Install Acrylic Panels to Side Panels

Lay one of the sides onto your work surface with the slots facing up. Insert the tabs from the acrylic panels into the slots on the left and right sides.

Installed Sides

Carefully fit the second side onto the acrylic panels. Fit the tabs from the acrylic panels into the slots on the side piece. Firmly press pieces together.

Final Build

And there you have it! The parts are wired up and the enclosure is assembled. Plug in a good data USB cable to power up the Feather. Optionally plug in any 3.7v battery from the Adafruit shop to the Feather to go portable. 

This guide was first published on Sep 29, 2020. It was last updated on Sep 29, 2020.