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docs/library/pyb.Timer: Document how to use BKIN pin with example.

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Document how to connect the Timer block BRK_IN to a physical Pin alternate
function.

Add an example of PWM Motor drive using complementary outputs with dead
time and break input to kill the PWM and generate a callback.

Signed-off-by: Chris Mason <c.mason@inchipdesign.com.au>
This commit is contained in:
chrismas9 2022-06-26 23:54:37 +10:00 committed by Damien George
parent 33ea400ce8
commit c038ea0cc6
1 changed files with 14 additions and 1 deletions
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15
docs/library/pyb.Timer.rst
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@ -111,7 +111,9 @@ Methods
the PWM when the ``BRK_IN`` input is asserted. The value of this
argument determines if break is enabled and what the polarity is, and
can be one of ``Timer.BRK_OFF``, ``Timer.BRK_LOW`` or
``Timer.BRK_HIGH``.
``Timer.BRK_HIGH``. To select the ``BRK_IN`` pin construct a Pin object with
``mode=Pin.ALT, alt=Pin.AFn_TIMx``. The pin's GPIO input features are
available in alt mode - ``pull=`` , ``value()`` and ``irq()``.
You must either specify freq or both of period and prescaler.
@ -204,6 +206,17 @@ Methods
ch2 = timer.channel(2, pyb.Timer.PWM, pin=pyb.Pin.board.X2, pulse_width=8000)
ch3 = timer.channel(3, pyb.Timer.PWM, pin=pyb.Pin.board.X3, pulse_width=16000)
PWM Motor Example with complementary outputs, dead time, break input and break callback::
from pyb import Timer
from machine import Pin # machine.Pin supports alt mode and irq on the same pin.
pin_t8_1 = Pin(Pin.board.Y1, mode=Pin.ALT, af=Pin.AF3_TIM8) # Pin PC6, TIM8_CH1
pin_t8_1n = Pin(Pin.board.X8, mode=Pin.ALT, af=Pin.AF3_TIM8) # Pin PA7, TIM8_CH1N
pin_bkin = Pin(Pin.board.X7, mode=Pin.ALT, af=Pin.AF3_TIM8) # Pin PA6, TIM8_BKIN
pin_bkin.irq(handler=break_callabck, trigger=Pin.IRQ_FALLING)
timer = pyb.Timer(8, freq=1000, deadtime=1008, brk=Timer.BRK_LOW)
ch1 = timer.channel(1, pyb.Timer.PWM, pulse_width_percent=30)
.. method:: Timer.counter([value])
Get or set the timer counter.