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# Example using PIO to drive a set of WS2812 LEDs.
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# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
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import array, time
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from machine import Pin
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import rp2
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# Configure the number of WS2812 LEDs.
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NUM_LEDS = 8
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@rp2.asm_pio(
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sideset_init=rp2.PIO.OUT_LOW,
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out_shiftdir=rp2.PIO.SHIFT_LEFT,
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autopull=True,
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pull_thresh=24,
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)
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def ws2812():
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# fmt: off
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T1 = 2
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T2 = 5
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T3 = 3
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wrap_target()
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label("bitloop")
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out(x, 1) .side(0) [T3 - 1]
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jmp(not_x, "do_zero") .side(1) [T1 - 1]
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jmp("bitloop") .side(1) [T2 - 1]
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label("do_zero")
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nop() .side(0) [T2 - 1]
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wrap()
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# fmt: on
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# Create the StateMachine with the ws2812 program, outputting on Pin(22).
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sm = rp2.StateMachine(0, ws2812, freq=8_000_000, sideset_base=Pin(22))
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# Start the StateMachine, it will wait for data on its FIFO.
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sm.active(1)
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# Display a pattern on the LEDs via an array of LED RGB values.
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ar = array.array("I", [0 for _ in range(NUM_LEDS)])
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# Cycle colours.
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for i in range(4 * NUM_LEDS):
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for j in range(NUM_LEDS):
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r = j * 100 // (NUM_LEDS - 1)
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b = 100 - j * 100 // (NUM_LEDS - 1)
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if j != i % NUM_LEDS:
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r >>= 3
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b >>= 3
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ar[j] = r << 16 | b
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sm.put(ar, 8)
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time.sleep_ms(50)
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# Fade out.
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for i in range(24):
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for j in range(NUM_LEDS):
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ar[j] = ar[j] >> 1 & 0x7F7F7F
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sm.put(ar, 8)
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time.sleep_ms(50)
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