Use DMA
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dma_ws2812.py
149
dma_ws2812.py
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@ -1,43 +1,18 @@
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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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# Example using PIO to drive a set of WS2812 LEDs.
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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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from time import sleep
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import dma
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# Configure the number of WS2812 LEDs.
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NUM_LEDS = 9
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NUM_LEDS = 256
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PIN_NUM = 0
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brightness = 0.2
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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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@rp2.asm_pio(sideset_init=rp2.PIO.OUT_LOW, out_shiftdir=rp2.PIO.SHIFT_RIGHT, autopull=True, pull_thresh=24)
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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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@ -49,39 +24,91 @@ def ws2812():
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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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class WS2812B:
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def __init__(self, num_leds, pin_num, brightness, state_machine):
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# Create the StateMachine with the ws2812 program, outputting on pin
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self.sm = rp2.StateMachine(state_machine, ws2812, freq=8_000_000, sideset_base=Pin(pin_num))
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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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self.sm.active(1)
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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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self.ar = array.array("I", [0 for _ in range(num_leds)])
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self.num_leds = num_leds
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self.brightness = brightness
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self.pio_dma = dma.PIO_DMA_Transfer(state_machine+4, state_machine, 32, num_leds)
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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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def show(self):
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#self.sm.put(self.ar)
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self.pio_dma.start_transfer(self.ar)
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def set(self, i, color):
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self.ar[i] = int((color[1]<<16)*self.brightness) + int((color[0]<<8)*self.brightness) + int(color[2]*self.brightness)
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def fill(self, color):
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for i in range(len(self.ar)):
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self.set(i, color)
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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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def wait(self):
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return self.pio_dma.busy()
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dma_out()
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time.sleep(1)
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def color_chase(self, color, wait):
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for i in range(self.num_leds):
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self.set(i, color)
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time.sleep(wait)
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self.show()
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time.sleep(0.2)
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def wheel(self, pos):
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# Input a value 0 to 255 to get a color value.
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# The colours are a transition r - g - b - back to r.
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if pos < 0 or pos > 255:
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return (0, 0, 0)
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if pos < 85:
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return (255 - pos * 3, pos * 3, 0)
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if pos < 170:
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pos -= 85
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return (0, 255 - pos * 3, pos * 3)
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pos -= 170
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return (pos * 3, 0, 255 - pos * 3)
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def rainbow_cycle(self, wait):
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for j in range(255):
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for i in range(self.num_leds):
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rc_index = (i * 256 // self.num_leds) + j
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self.set(i, self.wheel(rc_index & 255))
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self.show()
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time.sleep(wait)
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BLACK = (0, 0, 0)
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RED = (255, 0, 0)
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YELLOW = (255, 150, 0)
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GREEN = (0, 255, 0)
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CYAN = (0, 255, 255)
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BLUE = (0, 0, 255)
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PURPLE = (180, 0, 255)
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WHITE = (255, 255, 255)
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COLORS = (BLACK, RED, YELLOW, GREEN, CYAN, BLUE, PURPLE, WHITE)
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if __name__ == "__main__":
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ws0 = WS2812B(256, 1, 1, 1)
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ws1 = WS2812B(256, 2, 1, 5)
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ws2 = WS2812B(256, 3, 1, 6)
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while True:
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for color in ws0.COLORS:
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ws0.fill(color)
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ws0.show()
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ws1.fill(color)
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ws1.show()
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ws2.fill(color)
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ws2.show()
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time.sleep(1)
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