73 lines
2.1 KiB
Markdown
73 lines
2.1 KiB
Markdown
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# Raspberry Pi Pico 资源总结
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## API、Demo 及网络资源
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- [Raspberry Pi Pico and Pico W 官网说明及资源](https://www.raspberrypi.com/documentation/microcontrollers/raspberry-pi-pico.html)
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- [MicroPython documentation](https://docs.micropython.org/en/latest/index.html)：分为
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- Python standard libraries and micro-libraries
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- MicroPython-specific libraries
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- Port-specific libraries：其中 rp2 为 Raspberry Pi Pico 的 Port-specific library.
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- [MicroPython 文档(中文版)](http://www.86x.org/en/latet/index-2.html)
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## 特定功能代码段
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### 测量 PWM 周期和占空比
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```python
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from machine import Pin, PWM
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from rp2 import PIO, StateMachine, asm_pio
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import time
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@rp2.asm_pio(set_init=rp2.PIO.IN_LOW, autopush=True, push_thresh=32)
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def period():
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wrap_target()
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set(x, 0)
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wait(0, pin, 0) # Wait for pin to go low
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wait(1, pin, 0) # Low to high transition
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label('low_high')
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jmp(x_dec, 'next') [1] # unconditional
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label('next')
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jmp(pin, 'low_high') # while pin is high
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label('low') # pin is low
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jmp(x_dec, 'nxt')
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label('nxt')
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jmp(pin, 'done') # pin has gone high: all done
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jmp('low')
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label('done')
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in_(x, 32) # Auto push: SM stalls if FIFO full
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wrap()
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@rp2.asm_pio(set_init=rp2.PIO.IN_LOW, autopush=True, push_thresh=32)
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def mark():
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wrap_target()
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set(x, 0)
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wait(0, pin, 0) # Wait for pin to go low
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wait(1, pin, 0) # Low to high transition
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label('low_high')
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jmp(x_dec, 'next') [1] # unconditional
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label('next')
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jmp(pin, 'low_high') # while pin is high
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in_(x, 32) # Auto push: SM stalls if FIFO full
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wrap()
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pin16 = Pin(16, Pin.IN, Pin.PULL_UP)
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sm0 = rp2.StateMachine(0, period, in_base=pin16, jmp_pin=pin16)
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sm0.active(1)
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sm1 = rp2.StateMachine(1, mark, in_base=pin16, jmp_pin=pin16)
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sm1.active(1)
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pwm = PWM(Pin(17))
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pwm.freq(1000)
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pwm.duty_u16(0xffff // 3)
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# Clock is 125MHz. 3 cycles per iteration, so unit is 24.0ns
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def scale(v):
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return (1 + (v ^ 0xffffffff)) * 24e-6 # Scale to ms
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while True:
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period = scale(sm0.get())
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mark = scale(sm1.get())
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print(period, mark, mark/period)
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time.sleep(0.2)
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```
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