qtpy_knob_scroller.py

# qtpy_knob_scroller.py -- Mount a rotary encoder directly to an Adafruit QT Py,
#                          add some neopixels and get a USB scrolling knob
#                          Turning knob scrolls vertically,
#                          pressing & turning scrolls horizontally
# https://github.com/todbot/qtpy-knob
# 2021-2023 @todbot / Tod Kurt
#

import os
import time
import board
from digitalio import DigitalInOut, Direction, Pull
from adafruit_hid.mouse import Mouse
from adafruit_hid.keyboard import Keyboard,Keycode
import gc
gc.collect()  # not much space on SAMD21 devices any more
import neopixel
import usb_hid

if os.uname().machine.find("rp2040") > 0:  # RP2040
    from fakerotaryio import IncrementalEncoder
else:
    from rotaryio import IncrementalEncoder

# 16 position neopixel ring
ring = neopixel.NeoPixel(board.MISO, 16, brightness=0.2, auto_write=False)

# button of rotary encoder
button = DigitalInOut(board.MOSI)
button.pull = Pull.UP

# Use pin A2 as a fake ground for the rotary encoder
fakegnd = DigitalInOut(board.A2)
fakegnd.switch_to_output(value=False)

encoder = IncrementalEncoder( board.A3, board.A1 )

mouse = Mouse(usb_hid.devices)
keyboard = Keyboard(usb_hid.devices)

print("hello from qtpy-knob-scroller!!!")

# standard colorwheel
def colorwheel(pos):
    if pos < 0 or pos > 255:
        (r,g,b) = (0,0,0)
    elif pos < 85:
        (r,g,b) = (int(pos * 3), int(255 - pos * 3), 0)
    elif pos < 170:
        pos -= 85
        (r,g,b) = (int(255 - pos * 3), 0, int(pos * 3))
    else:
        pos -= 170
        (r,g,b) = (0, int(pos * 3), int(255 - pos * 3))
    return (r, g, b)


last_encoder_val = encoder.position
ring_pos = 0
rainbow_pos = 0

def scroll(diff):
    if diff > 0:
        for i in range(diff):
            mouse.move(0,0, 1)
            time.sleep(0.01)
    elif diff < 0:
        for i in range(-diff):
            mouse.move(0,0, -1)
            time.sleep(0.01)

while True:
    diff = last_encoder_val - encoder.position  # encoder clicks since last read
    last_encoder_val = encoder.position
    ring_pos = (ring_pos + diff) % len(ring)    # position on LED ring
    hue = colorwheel( encoder.position*4 % 255 )     # fun hue change based on pos

    if not button.value:                        # button pressed
        keyboard.press(Keycode.LEFT_SHIFT)
        scroll(diff)
        keyboard.release(Keycode.LEFT_SHIFT)
        for i in range(len(ring)):          # spin the rainbow while held
            pixel_index = (i*256 // len(ring)) + rainbow_pos
            ring[i] = colorwheel( pixel_index & 255 )
            ring.show()
            rainbow_pos = (rainbow_pos + 1) % 256
    else:
        scroll(diff)

        ring.fill( [int(i/4) for i in hue] ) # make it 1/4 dimmer
        ring[ring_pos] = (255,255,255)
        ring[(ring_pos-1)%len(ring)] = (67,67,67)
        ring[(ring_pos+1)%len(ring)] = (67,67,67)
        ring.show()

    print(encoder.position,diff,button.value,ring_pos)
    time.sleep(0.05)