pico8enc -- 8 rotary encoders on a Raspberry Pi Pico

Turns out you can hook up 8 rotary encoders w/ switches to Raspberry Pi Pico with no extra hardware. Pretty cool!

With CircuitPython, it becomes pretty easy to actually read these encoders since all hard, timing-critical work is done inside the C-based rotaryio library that comes standard with CircuitPython.

One "twist" to look out for (haha): the two rotary encoder pins must be hooked up to adjacent pins on the Pico, because of how rotaryio uses the Pico's PIO module to handle reading the encoder pulses.

The core of the code looks like this:

encoder_pins = ( (board.GP12, board.GP13, board.GP16),  # pin A, pin B, pin for switch
                 (board.GP10, board.GP11, board.GP17),
                 (board.GP8, board.GP9, board.GP18),
                 (board.GP6, board.GP7, board.GP19),
                 # ...
                 )
encoders = []
encoder_buttons = []
for pins in encoder_pins:
    pin_A, pin_B, pin_switch = pins
    encoder = rotaryio.IncrementalEncoder( pin_A, pin_B )
    button = DigitalInOut(pin_switch)
    button.pull = Pull.UP
    encoders.append(encoder)
    encoder_buttons.append(button)

while True:
    for i in range(len(encoders)):
      position = encoders[i].position
      button_press = encoder_buttons[i].value