Coding the Wireless BLE Encoder Remote

Save Subscribe

Once you've finished setting up your Feather nRF52840 with CircuitPython, you can access the code and necessary libraries by downloading the Project Bundle.

To do this, click on the Download Project Bundle button in the window below. It will download as a zipped folder.

Download Project Bundle
Copy Code 
# SPDX-FileCopyrightText: 2022 Liz Clark for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import board
from digitalio import DigitalInOut, Direction, Pull
import rotaryio
from adafruit_debouncer import Button
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode
import adafruit_ble
from adafruit_ble.advertising import Advertisement
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.standard.hid import HIDService

#  pin assignments for the rotary encoder
ENCA = board.SDA
ENCB = board.SCL
COMA = board.D5
CENTER = board.D6
RIGHT = board.D9
UP = board.D10
LEFT = board.D11
DOWN = board.D12
COMB = board.D13

#  mode slide switch pin
SWITCH = board.A1

# Rotary encoder setup
encoder = rotaryio.IncrementalEncoder(ENCA, ENCB)
last_position = 0

# setting the COMA and COMB pins to LOW aka GND
com_a = DigitalInOut(COMA)
com_a.switch_to_output()
com_a = False
com_b = DigitalInOut(COMB)
com_b.switch_to_output()
com_b = False

#  mode switch setup
SWITCH = DigitalInOut(board.A1)
SWITCH.direction = Direction.INPUT
SWITCH.pull = Pull.UP

#  encoder button pins
enc_buttons = (
    CENTER,
    UP,
    LEFT,
    DOWN,
    RIGHT,
)

#  array for the encoder buttons
inputs = []

#  setting the encoder buttons as inputs
for enc in enc_buttons:
    enc_button = DigitalInOut(enc)
    enc_button.pull = Pull.UP
	#  adding to the inputs array with the Button Class of the Debouncer lib
    inputs.append(Button(enc_button))

#  streaming mode keycodes
CHILL_CODES = (
    Keycode.SPACE,
    Keycode.F,
    Keycode.LEFT_ARROW,
    Keycode.M,
    Keycode.RIGHT_ARROW,
)

#  doom mode keycodes
DOOM_CODES = (
    Keycode.CONTROL,
    Keycode.UP_ARROW,
    Keycode.LEFT_ARROW,
    Keycode.DOWN_ARROW,
    Keycode.RIGHT_ARROW,
)

#  streaming state
chill = True
#  doom state
doom = False

#  BLE HID setup
hid = HIDService()

advertisement = ProvideServicesAdvertisement(hid)
advertisement.appearance = 961
scan_response = Advertisement()
scan_response.complete_name = "CircuitPython HID"

#  BLE instance
ble = adafruit_ble.BLERadio()

#  keyboard HID setup
kbd = Keyboard(hid.devices)

#  BLE advertisement
if not ble.connected:
    print("advertising")
    ble.start_advertising(advertisement, scan_response)
else:
    print("connected")
    print(ble.connections)

while True:
	#  check for BLE connection
    while not ble.connected:
        pass
	#  while BLE connected
    while ble.connected:
		#  mode switch
		#  selects whether to be in streaming mode or doom mode
		#  affects the keycodes assigned to the encoder's inputs
        if not SWITCH.value:
            chill = False
            doom = True
        if SWITCH.value:
            chill = True
            doom = False

		#  rotary encoder position tracking
        position = encoder.position
		#  if the encoder is turned to the right
        if position > last_position:
			#  if in streaming mode
            if chill:
				#  send UP arrow for volume
                kbd.send(Keycode.UP_ARROW)
			#  if in doom mode
            if doom:
				#  send period for right strafe
                kbd.send(Keycode.PERIOD)
			#  reset encoder position
            last_position = position
		#  if the encoder is turned to the left
        if position < last_position:
            #  if in streaming mode
            if chill:
				#  send DOWN arrow for volume
                kbd.send(Keycode.DOWN_ARROW)
			#  if in doom mode
            if doom:
				#  send comma for left strafe
                kbd.send(Keycode.COMMA)
			#  reset encoder position
            last_position = position

		#  for loop for keycodes
        for i in range(5):
			#  update state of the buttons
            inputs[i].update()
			#  if you press the center button for a long press
            if inputs[0].long_press:
				#  sends space key
				#  used in Doom for use/open
                kbd.send(Keycode.SPACE)
			#  if a press is detected...
            if inputs[i].pressed:
				#  if in streaming mode
                if chill:
					#  send the streaming keycodes
                    kbd.press(CHILL_CODES[i])
				#  if in doom mode
                if doom:
					#  send the doom keycodes
                    kbd.press(DOOM_CODES[i])
			#  if a button is released...
            if inputs[i].released:
				#  if in streaming mode
                if chill:
					#  release the streaming keycodes
                    kbd.release(CHILL_CODES[i])
				#  if in doom mode
                if doom:
					#  release the doom keycodes
                    kbd.release(DOOM_CODES[i])

	#  if BLE disconnects, begin advertising again
    ble.start_advertising(advertisement)
View on GitHub

Upload the Code and Libraries to the Feather nRF52840

After downloading the Project Bundle, plug your Feather nRF52840 into the computer's USB port with a known good USB data+power cable. You should see a new flash drive appear in the computer's File Explorer or Finder (depending on your operating system) called CIRCUITPY. Unzip the folder and copy the following items to the Feather nRF52840's CIRCUITPY drive. 

  • lib folder
  • code.py

Your Feather nRF52840 CIRCUITPY drive should look like this after copying the lib folder and the code.py file.

cp

How the CircuitPython Code Works

The rotary encoder's five buttons are setup as inputs using the Button class of the adafruit_debouncer library. The adafruit_debouncer library is being used so that the long_press property can be used in the loop.

Download File
Copy Code 
#  encoder button pins
enc_buttons = (
    CENTER,
    UP,
    LEFT,
    DOWN,
    RIGHT,
)

#  array for the encoder buttons
inputs = []

#  setting the encoder buttons as inputs
for enc in enc_buttons:
    enc_button = DigitalInOut(enc)
    enc_button.pull = Pull.UP
	#  adding to the inputs array with the Button Class of the Debouncer lib
    inputs.append(Button(enc_button))

Keycodes

There are two sets of keycodes depending on the mode of the remote. The keycodes in CHILL_CODES are for streaming media, such as Netflix or YouTube. The keycodes in DOOM_CODES are for playing classic Doom. The keycode indexes align with the encoder buttons array's indexes. For example, the CENTER button will send the SPACE or CONTROL keycode, depending on the mode.

Download File
Copy Code 
#  streaming mode keycodes
CHILL_CODES = (
    Keycode.SPACE,
    Keycode.F,
    Keycode.LEFT_ARROW,
    Keycode.M,
    Keycode.RIGHT_ARROW,
)

#  doom mode keycodes
DOOM_CODES = (
    Keycode.CONTROL,
    Keycode.UP_ARROW,
    Keycode.LEFT_ARROW,
    Keycode.DOWN_ARROW,
    Keycode.RIGHT_ARROW,
)

The Loop

Once a BLE connection has been established, the loop checks the value of SWITCH to determine the mode of the controller.

Download File
Copy Code 
while ble.connected:
		#  mode switch
		#  selects whether to be in streaming mode or doom mode
		#  affects the keycodes assigned to the encoder's inputs
        if not SWITCH.value:
            chill = False
            doom = True
        if SWITCH.value:
            chill = True
            doom = False

Encoder Position

The encoder also sends a keycode depending on the mode. The loop checks to see if the encoder is turning to the left or right. Depending on the direction, a keycode will be sent. 

In streaming mode, the encoder controls volume. In Doom, it controls left and right strafe.

Download File
Copy Code 
#  rotary encoder position tracking
        position = encoder.position
		#  if the encoder is turned to the right
        if position > last_position:
			#  if in streaming mode
            if chill:
				#  send UP arrow for volume
                kbd.send(Keycode.UP_ARROW)
			#  if in doom mode
            if doom:
				#  send period for right strafe
                kbd.send(Keycode.PERIOD)
			#  reset encoder position
            last_position = position
		#  if the encoder is turned to the left
        if position < last_position:
            #  if in streaming mode
            if chill:
				#  send DOWN arrow for volume
                kbd.send(Keycode.DOWN_ARROW)
			#  if in doom mode
            if doom:
				#  send comma for left strafe
                kbd.send(Keycode.COMMA)
			#  reset encoder position
            last_position = position

Sending Keycodes

The adafruit_debouncer library checks the status of the button inputs using update(). A for statement is used to iterate through all five buttons. If the center button receives a long_press, then the SPACE keycode is sent. This is used in Doom for the use/open control.

Otherwise, the for statement checks to see if a button has been pressed or released. If a button is pressed, then the corresponding keycode is pressed depending on the mode. If a button is released, then the corresponding keycode is released depending on the mode.

Download File
Copy Code 
#  for loop for keycodes
        for i in range(5):
			#  update state of the buttons
            inputs[i].update()
			#  if you press the center button for a long press
            if inputs[0].long_press:
				#  sends space key
				#  used in Doom for use/open
                kbd.send(Keycode.SPACE)
			#  if a press is detected...
            if inputs[i].pressed:
				#  if in streaming mode
                if chill:
					#  send the streaming keycodes
                    kbd.press(CHILL_CODES[i])
				#  if in doom mode
                if doom:
					#  send the doom keycodes
                    kbd.press(DOOM_CODES[i])
			#  if a button is released...
            if inputs[i].released:
				#  if in streaming mode
                if chill:
					#  release the streaming keycodes
                    kbd.release(CHILL_CODES[i])
				#  if in doom mode
                if doom:
					#  release the doom keycodes
                    kbd.release(DOOM_CODES[i])
 CircuitPython for Feather nRF52840 Wiring 

This guide was first published on Apr 13, 2022. It was last updated on Dec 09, 2023.

This page (Coding the Wireless BLE Encoder Remote) was last updated on Dec 09, 2023.

Text editor powered by tinymce.