8000 docs/esp32: Explain ESP32 PWM modes, timers, and channels. · micropython/micropython@71111cf · GitHub
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docs/esp32: Explain ESP32 PWM modes, timers, and channels.
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‎docs/esp32/quickref.rst

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@@ -16,7 +16,7 @@ working with this board it may be useful to get an overview of the microcontroll
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:maxdepth: 1
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general.rst
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tutorial/intro.rst
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tutorial/index.rst
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Installing MicroPython
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----------------------
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from machine import Pin, PWM
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pwm0 = PWM(Pin(0)) # create PWM object from a pin
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pwm0.freq() # get current frequency
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pwm0.freq() # get current frequency (default 5kHz)
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pwm0.freq(1000) # set frequency
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pwm0.duty() # get current duty cycle
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pwm0.duty() # get current duty cycle (default 512, 50%)
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pwm0.duty(200) # set duty cycle
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pwm0.deinit() # turn off PWM on the pin
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pwm2 = PWM(Pin(2), freq=20000, duty=512) # create and configure in one go
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pwm2 = PWM(Pin(2), freq=20000, duty=512) # create and configure in one go
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ESP chips have different hardware peripherals:
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===================================================== ======== ======== ========
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Hardware specification ESP32 ESP32-S2 ESP32-C3
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----------------------------------------------------- -------- -------- --------
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Number of groups (speed modes) 2 1 1
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Number of timers per group 4 4 4
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Number of channels per group 8 8 6
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----------------------------------------------------- -------- -------- --------
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Different of PWM frequencies (groups * timers) 8 4 4
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Total PWM channels (Pins, duties) (groups * channels) 16 8 6
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===================================================== ======== ======== ========
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A maximum number of PWM channels (Pins) are available on the ESP32 - 16 channels,
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but only 8 different PWM frequencies are available, the remaining 8 channels must
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have the same frequency. On the other hand, 16 independent PWM duty cycles are
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possible at the same frequency.
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ADC (analog to digital conversion)
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----------------------------------

‎docs/esp32/tutorial/index.rst

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.. _esp32_tutorial:
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MicroPython tutorial for ESP32
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==============================
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This tutorial is intended to get you started using MicroPython on the ESP32
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system-on-a-chip. If it is your first time it is recommended to follow the
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tutorial through in the order below. Otherwise the sections are mostly self
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contained, so feel free to skip to those that interest you.
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The tutorial does not assume that you know Python, but it also does not attempt
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to explain any of the details of the Python language. Instead it provides you
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with commands that are ready to run, and hopes that you will gain a bit of
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Python knowledge along the way. To learn more about Python itself please refer
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to `<https://www.python.org>`__.
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.. toctree::
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:maxdepth: 1
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:numbered:
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intro.rst
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pwm.rst

‎docs/esp32/tutorial/pwm.rst

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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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