50 lines
2.3 KiB
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50 lines
2.3 KiB
ReStructuredText
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.. _esp32_pwm:
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Pulse Width Modulation
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======================
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Pulse width modulation (PWM) is a way to get an artificial analog output on a
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digital pin. It achieves this by rapidly toggling the pin from low to high.
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There are two parameters associated with this: the frequency of the toggling,
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and the duty cycle. The duty cycle is defined to be how long the pin is high
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compared with the length of a single period (low plus high time). Maximum
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duty cycle is when the pin is high all of the time, and minimum is when it is
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low all of the time.
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More comprehensive example with all 16 PWM channels and 8 timers::
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from machine import Pin, PWM
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try:
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f = 100 # Hz
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d = 1024 // 16 # 6.25%
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pins = (15, 2, 4, 16, 18, 19, 22, 23, 25, 26, 27, 14 , 12, 13, 32, 33)
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pwms = []
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for i, pin in enumerate(pins):
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pwms.append(PWM(Pin(pin), freq=f * (i // 2 + 1), duty= 1023 if i==15 else d * (i + 1)))
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print(pwms[i])
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finally:
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for pwm in pwms:
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try:
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pwm.deinit()
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except:
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pass
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Output is::
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PWM(pin=15, freq=100, duty=64, resolution=10, mode=0, channel=0, timer=0)
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PWM(pin=2, freq=100, duty=128, resolution=10, mode=0, channel=1, timer=0)
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PWM(pin=4, freq=200, duty=192, resolution=10, mode=0, channel=2, timer=1)
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PWM(pin=16, freq=200, duty=256, resolution=10, mode=0, channel=3, timer=1)
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PWM(pin=18, freq=300, duty=320, resolution=10, mode=0, channel=4, timer=2)
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PWM(pin=19, freq=300, duty=384, resolution=10, mode=0, channel=5, timer=2)
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PWM(pin=22, freq=400, duty=448, resolution=10, mode=0, channel=6, timer=3)
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PWM(pin=23, freq=400, duty=512, resolution=10, mode=0, channel=7, timer=3)
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PWM(pin=25, freq=500, duty=576, resolution=10, mode=1, channel=0, timer=0)
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PWM(pin=26, freq=500, duty=640, resolution=10, mode=1, channel=1, timer=0)
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PWM(pin=27, freq=600, duty=704, resolution=10, mode=1, channel=2, timer=1)
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PWM(pin=14, freq=600, duty=768, resolution=10, mode=1, channel=3, timer=1)
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PWM(pin=12, freq=700, duty=832, resolution=10, mode=1, channel=4, timer=2)
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PWM(pin=13, freq=700, duty=896, resolution=10, mode=1, channel=5, timer=2)
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PWM(pin=32, freq=800, duty=960, resolution=10, mode=1, channel=6, timer=3)
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PWM(pin=33, freq=800, duty=1023, resolution=10, mode=1, channel=7, timer=3)
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