USB Media Controller

Here’s a little desktop media controller I just finished. It has 4 keys and a rotary encoder. I designed the case for it in Fusion360 and printed it myself. Cheap, easy, fun project with all the parts coming from Adafruit (see the details below). The knob changes the volume, and toggles mute when clicked in. The 4 keys control media playback or launch apps.

Faceplate Model

Base model

First iteration of the faceplate. I decided to make it bigger.

Assembling

Assembling

Finished, on my desk

Finished, on my desk

Details:

Hardware:

• Adafruit QT Py RP2040
• Adafruit NeoKey 1×4 QT I2C Board
• Adafruit I2C QT Rotary Encoder Board
• 2x STEMMA QT Cables [4-pin]
• Key Switches (I used the white ones)
• Keycaps (I had some clear ones around that I used)

Software:

The QT Pi runs CircuitPython, here’s the code for it (this is my code.py):

import time
import board
import busio
from digitalio import DigitalInOut, Direction, Pull
import rotaryio
from adafruit_neokey.neokey1x4 import NeoKey1x4
import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode
from adafruit_hid.consumer_control import ConsumerControl
from adafruit_hid.consumer_control_code import ConsumerControlCode
from adafruit_seesaw import seesaw, rotaryio, digitalio, neopixel
try:
    import _pixelbuf
except ImportError:
    import adafruit_pypixelbuf as _pixelbuf

# Initialize I2C Bus and board addresses
i2c = busio.I2C(board.SCL1, board.SDA1, frequency=786_000)
neokey = NeoKey1x4(i2c, addr=0x31)
seesaw = seesaw.Seesaw(i2c, addr=0x36)

encoder = rotaryio.IncrementalEncoder(seesaw)
seesaw.pin_mode(24, seesaw.INPUT_PULLUP)
button = digitalio.DigitalIO(seesaw, 24)

# Turn off Rotary Encoder Neopixel
pixel = neopixel.NeoPixel(seesaw, 6, 1)
pixel.brightness = 0.0
color = 0
pixel.fill(_pixelbuf.colorwheel(color))

last_encoder_val = encoder.position

kbd = Keyboard(usb_hid.devices)
cc = ConsumerControl(usb_hid.devices)
print("Media Controller")

# Neokey Stuff
#  states for key presses
key_0_state = False
key_1_state = False
key_2_state = False
key_3_state = False

while True:
    #  switch debouncing
    #  also turns off NeoPixel on release
    if not neokey[0] and key_0_state:
        key_0_state = False
        neokey.pixels[0] = 0x0
    if not neokey[1] and key_1_state:
        key_1_state = False
        neokey.pixels[1] = 0x0
    if not neokey[2] and key_2_state:
        key_2_state = False
        neokey.pixels[2] = 0x0
    if not neokey[3] and key_3_state:
        key_3_state = False
        neokey.pixels[3] = 0x0

    #  if 1st neokey is pressed...
    if neokey[0] and not key_0_state:
        print("Mute")
        neokey.pixels[0] = 0xFF0000
        cc.send(ConsumerControlCode.MUTE)
        #  update key state
        key_0_state = True

    #  if 2nd neokey is pressed...
    if neokey[1] and not key_1_state:
        print("Play/Pause")
        neokey.pixels[1] = 0xFFFF00
        cc.send(ConsumerControlCode.PLAY_PAUSE)
        #  update key state
        key_1_state = True

    #  if 3rd neokey is pressed...
    if neokey[2] and not key_2_state:
        print("Stop")
        neokey.pixels[2] = 0x00FF00
        cc.send(ConsumerControlCode.STOP)
        #  update key state
        key_2_state = True

    #  if 4th neokey is pressed...
    if neokey[3] and not key_3_state:
        print("Notepad")
        #  turn on NeoPixel
        neokey.pixels[3] = 0x00FFFF
        kbd.send(Keycode.WINDOWS, Keycode.THREE)
        time.sleep(0.5)
        #  update key state
        key_3_state = True

# Rotary Encoder stuff
    diff = last_encoder_val - encoder.position  # encoder clicks since last read
    last_encoder_val = encoder.position

    if button.value == False:                   # button pressed
        cc.send(ConsumerControlCode.MUTE)       # toggle mute
        while not button.value:                 # wait for release
            pass
    else:                                       # not pressed
        if diff > 0:
            cc.send(ConsumerControlCode.VOLUME_INCREMENT)
        elif diff < 0:
            cc.send(ConsumerControlCode.VOLUME_DECREMENT)
    time.sleep(0.01)