.. _snippet-pwm-servo:

PWM Servomotor Preset Snippet (pwm-servo)
#########################################

.. code-block:: console

   west build -S pwm-servo [...]

Overview
********

This snippet is quite board specific and prepares a dedicated PWM channel
exclusively for the standard :zephyr:code-sample:`servo-motor` sample from
Zephyr.

Board specific setups
=====================

Only selected boards are supported by this snippet. There is no basic
configuration.

Supported boards are:

* Cytron |Maker Pi RP2040|

Cytron Maker Pi RP2040
----------------------

.. _snippet-pwm-servo-cytron-maker-pi-rp2040:

Connect a servomotor :hwftlbl-act:`MG996R` to the first on-board PWM channel
for servomotors, the 4×3 pin header block at position 19. See the board
:ref:`positions diagram <cytron_maker_pi_rp2040_positions>` for details.

The corresponding PWM pulse widths for a range of :b:`-90°` to :b:`+90°` (180°)
are :bbl:`500 ㎲` to :bbl:`2,500 ㎲` with a :bbl:`period of 50 ㎐`. All these
servomotor specific parameters are preset by the snippet :ref:`snippet-pwm-servo`
that have to use to get access to this dedicated PWM channel together with the
original Zephyr :zephyr:code-sample:`servo-motor` sample. Invoke
:program:`west build` and :program:`west flash` with this snipped and optional
mixed with others, for example:

.. zephyr-app-commands::
   :app: zephyr/samples/basic/servo_motor
   :board: cytron_maker_pi_rp2040
   :build-dir: cytron_maker_rp2040
   :west-args: -p -S usb-console -S pwm-servo
   :flash-args: -r uf2
   :goals: flash
   :compact:

.. literalinclude:: ../../../../../bridle/snippets/pwm-servo/boards/cytron_maker_pi_rp2040.overlay
   :caption: boards/cytron_maker_pi_rp2040.overlay
   :language: DTS
   :encoding: ISO-8859-1
   :emphasize-lines: 3-4
   :linenos:
   :start-at: servo:
   :end-at: };

How to add support of a new board
*********************************

* add board devicetree overlay to this snippet;
* which add following options to the dedicated PWM node:

  - :dts:`compatible = "pwm-servo";`
  - :dts:`min-pulse = <PWM_USEC(500)>;`
  - :dts:`max-pulse = <PWM_USEC(2500)>;`