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# 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)
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