9e964d0a61
The sample did not use PWM in a proper way: it relied on a PWM device
handle, but channel or flags were hardcoded in the code. This patch
changes the sample to use a local binding ("pwm-servo") where the `pwms`
property is defined. This allows to make use of pwm_dt_spec facilities,
reducing the overall sample complexity and making it more portable
without editing the source code. The custom binding also requires to
provide the minimum/maximum pulse width so that different servos can be
easily plugged in without the need to edit sources.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
64 lines
1.7 KiB
ReStructuredText
64 lines
1.7 KiB
ReStructuredText
.. _servo-motor-sample:
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Servomotor
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##########
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Overview
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********
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This is a sample app which drives a servomotor using PWM.
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The sample rotates a servomotor back and forth in the 180 degree range with a
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PWM control signal.
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This app is targeted for servomotor ROB-09065. The corresponding PWM pulse
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widths for a 0 to 180 degree range are 700 to 2300 microseconds, respectively.
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Different servomotors may require different PWM pulse widths, and you may need
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to modify the source code if you are using a different servomotor.
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Requirements
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************
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The sample requires a servomotor whose signal pin is connected to a pin driven
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by PWM. The servo must be defined in Devicetree using the ``pwm-servo``
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compatible (part of the sample) and setting its node label to ``servo``. You
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will need to do something like this:
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.. code-block:: devicetree
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/ {
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servo: servo {
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compatible = "pwm-servo";
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pwms = <&pwm0 1 PWM_MSEC(20) PWM_POLARITY_NORMAL>;
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min-pulse = <PWM_USEC(700)>;
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max-pulse = <PWM_USEC(2500)>;
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};
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};
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Note that a commonly used period value is 20 ms. See
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:zephyr_file:`samples/basic/servo_motor/boards/bbc_microbit.overlay` for an
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example.
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Wiring
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******
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BBC micro:bit
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=============
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You will need to connect the motor's red wire to external 5V, the black wire to
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ground and the white wire to the SCL pin, i.e. pin P19 on the edge connector.
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Building and Running
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********************
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The sample has a devicetree overlay for the :ref:`bbc_microbit`.
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This sample can be built for multiple boards, in this example we will build it
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for the bbc_microbit board:
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.. zephyr-app-commands::
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:zephyr-app: samples/basic/servo_motor
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:board: bbc_microbit
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:goals: build flash
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:compact:
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