Brightness Consumer Codes
To change the brightness up and down we can send HID media consumer control codes for brightness up and down. The adafruit_hid library makes sending these easy.
Main Logic
Every few seconds, ACTION_INTERVAL, the program will check how many values the rotary encoder has changed by.
- If it is less than
STAY_EVEN_CHANGE_THRESHOLD, we send the brightness down code. - If it is above
STAY_EVEN_CHANGE_THRESHOLD, it will remain steady not changing the brightness. - If it's over
INCREASE_CHANGE_THRESHOLD, we will send the brightness up code.
Different devices will have different brightness levels. You can change the threshold variables or ACTION_INTERVAL to suit your device or to make it easier or harder to keep the brightness up.
Alternate Code - Pausing
In the version below, pressing the rotary encoder button will pause the device so that it won't change the brightness until resumed by pressing the button again.
# SPDX-FileCopyrightText: 2021 foamyguy for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""
Rotary Trinkey gadget that forces you to crank the handle in order
to keep the brightness up on your phone or tablet.
"""
import time
import math
import board
import digitalio
import rotaryio
import usb_hid
from adafruit_hid.consumer_control import ConsumerControl
from adafruit_hid.consumer_control_code import ConsumerControlCode
# how frequently we check the encoder value and apply brightness changes
ACTION_INTERVAL = 3 # seconds
# if encoder value increases at least this much
# then brightness stays the same
# if encoder value increases less than this
# then brightness goes down
STAY_EVEN_CHANGE_THRESHOLD = 60
# if encoder value increases at least this much
# then brightness goes up
INCREASE_CHANGE_THRESHOLD = 95
# timestamp of last time an action occurred
LAST_ACTION_TIME = 0
# encoder value variable
CUR_VALUE = 0
# pause state
PAUSED = False
cc = ConsumerControl(usb_hid.devices)
encoder = rotaryio.IncrementalEncoder(board.ROTA, board.ROTB)
switch = digitalio.DigitalInOut(board.SWITCH)
switch.switch_to_input(pull=digitalio.Pull.DOWN)
switch_state = None
# previous encoder position variable
last_position = encoder.position
# previous switch variable
prev_switch_value = False
while True:
now = time.monotonic()
if switch.value and not prev_switch_value:
print("toggling pause")
PAUSED = not PAUSED
if not PAUSED:
LAST_ACTION_TIME = now
prev_switch_value = switch.value
# read current encoder value
current_position = encoder.position
position_change = int(current_position - last_position)
# positive change
if position_change > 0:
for _ in range(position_change):
CUR_VALUE += position_change
# negative change
elif position_change < 0:
for _ in range(-position_change):
# use absolute value to convert to positive
CUR_VALUE += int(math.fabs(position_change))
last_position = current_position
if not PAUSED:
# is it time for an action?
if now > LAST_ACTION_TIME + ACTION_INTERVAL:
print(CUR_VALUE)
# update previous time variable
LAST_ACTION_TIME = now
# less than stay even threshold
if CUR_VALUE < STAY_EVEN_CHANGE_THRESHOLD:
cc.send(ConsumerControlCode.BRIGHTNESS_DECREMENT)
print("brightness down")
# more than stay even threshold
elif CUR_VALUE < INCREASE_CHANGE_THRESHOLD:
print("stay even")
# more than increase threshold
else:
cc.send(ConsumerControlCode.BRIGHTNESS_INCREMENT)
print("brightness up")
# reset encoder value
CUR_VALUE = 0
Page last edited January 21, 2025
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