88 lines
1.9 KiB
Python
88 lines
1.9 KiB
Python
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# Example based on pio_ws2812.py, but modified to use
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# a DMA channel to push out the data to the PIO
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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 = 9
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SM = 0
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PIO0_BASE = 0x50200000
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PIO1_BASE = 0x50300000
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PIO0_BASE_TXF0 = PIO0_BASE+0x10
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PIO0_BASE_TXF1 = PIO0_BASE+0x14
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PIO0_BASE_TXF2 = PIO0_BASE+0x18
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PIO0_BASE_TXF3 = PIO0_BASE+0x1c
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PIO1_BASE_TXF0 = PIO1_BASE+0x10
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PIO1_BASE_TXF1 = PIO1_BASE+0x14
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PIO1_BASE_TXF2 = PIO1_BASE+0x18
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PIO1_BASE_TXF3 = PIO1_BASE+0x1c
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if SM < 4:
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TFX = PIO0_BASE+0x10 + SM * 4
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else:
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TFX = PIO1_BASE+0x10 + (SM-4) * 4
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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(2).
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sm = rp2.StateMachine(SM, ws2812, freq=8_000_000, sideset_base=Pin(0))
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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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# Dummy data
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ar = array.array("I", [0 for _ in range(NUM_LEDS)])
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r = 0xff
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g = 0xff
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b = 0xff
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ar[0] = 0xff000000
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ar[1] = 0x00ff0000
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ar[2] = 0x0000ff00
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ar[3] = r<<24 + g<<16 + b<<8
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# starts the transfer, using DMA channel 0
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def dma_out():
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import dma, uctypes
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dma.init_channels()
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d0=dma.CHANNELS[0]
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d0.CTRL_TRIG.EN = 0
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d0.TRANS_COUNT = NUM_LEDS
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d0.READ_ADDR = uctypes.addressof(ar)
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d0.WRITE_ADDR = TFX
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d0.CTRL_TRIG.INCR_WRITE = 0
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d0.CTRL_TRIG.INCR_READ = 1
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d0.CTRL_TRIG.DATA_SIZE = 2
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d0.CTRL_TRIG.EN = 1
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dma_out()
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time.sleep(1)
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