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These files all use decorators (@asm_thumb, @asm_pio) that add names to the function scope, that the linter cannot see. It's useful to clear them in the file not in pyproject.toml as example code will be copied and adapted elsewhere, and those developers may also use Ruff (we hope!) Signed-off-by: Angus Gratton <angus@redyak.com.au>
48 lines
1.4 KiB
Python
48 lines
1.4 KiB
Python
# Example of using PIO for PWM, and fading the brightness of an LED
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# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
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from machine import Pin
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from rp2 import PIO, StateMachine, asm_pio
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from time import sleep
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@asm_pio(sideset_init=PIO.OUT_LOW)
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def pwm_prog():
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# fmt: off
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pull(noblock) .side(0)
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mov(x, osr) # Keep most recent pull data stashed in X, for recycling by noblock
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mov(y, isr) # ISR must be preloaded with PWM count max
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label("pwmloop")
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jmp(x_not_y, "skip")
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nop() .side(1)
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label("skip")
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jmp(y_dec, "pwmloop")
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# fmt: on
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class PIOPWM:
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def __init__(self, sm_id, pin, max_count, count_freq):
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self._sm = StateMachine(sm_id, pwm_prog, freq=2 * count_freq, sideset_base=Pin(pin))
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# Use exec() to load max count into ISR
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self._sm.put(max_count)
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self._sm.exec("pull()")
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self._sm.exec("mov(isr, osr)")
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self._sm.active(1)
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self._max_count = max_count
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def set(self, value):
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# Minimum value is -1 (completely turn off), 0 actually still produces narrow pulse
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value = max(value, -1)
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value = min(value, self._max_count)
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self._sm.put(value)
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# Pin 25 is LED on Pico boards
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pwm = PIOPWM(0, 25, max_count=(1 << 16) - 1, count_freq=10_000_000)
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while True:
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for i in range(256):
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pwm.set(i**2)
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sleep(0.01)
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