micropython/examples/rp2/pio_ws2812.py

# Example using PIO to drive a set of WS2812 LEDs.

# ruff: noqa: F821 - @asm_pio decorator adds names to function scope

import array, time
from machine import Pin
import rp2

# Configure the number of WS2812 LEDs.
NUM_LEDS = 8


@rp2.asm_pio(
    sideset_init=rp2.PIO.OUT_LOW,
    out_shiftdir=rp2.PIO.SHIFT_LEFT,
    autopull=True,
    pull_thresh=24,
)
def ws2812():
    # fmt: off
    T1 = 2
    T2 = 5
    T3 = 3
    wrap_target()
    label("bitloop")
    out(x, 1)               .side(0)    [T3 - 1]
    jmp(not_x, "do_zero")   .side(1)    [T1 - 1]
    jmp("bitloop")          .side(1)    [T2 - 1]
    label("do_zero")
    nop()                   .side(0)    [T2 - 1]
    wrap()
    # fmt: on


# Create the StateMachine with the ws2812 program, outputting on Pin(22).
sm = rp2.StateMachine(0, ws2812, freq=8_000_000, sideset_base=Pin(22))

# Start the StateMachine, it will wait for data on its FIFO.
sm.active(1)

# Display a pattern on the LEDs via an array of LED RGB values.
ar = array.array("I", [0 for _ in range(NUM_LEDS)])

# Cycle colours.
for i in range(4 * NUM_LEDS):
    for j in range(NUM_LEDS):
        r = j * 100 // (NUM_LEDS - 1)
        b = 100 - j * 100 // (NUM_LEDS - 1)
        if j != i % NUM_LEDS:
            r >>= 3
            b >>= 3
        ar[j] = r << 16 | b
    sm.put(ar, 8)
    time.sleep_ms(50)

# Fade out.
for i in range(24):
    for j in range(NUM_LEDS):
        ar[j] = ar[j] >> 1 & 0x7F7F7F
    sm.put(ar, 8)
    time.sleep_ms(50)