incubator-nuttx/Documentation/components/drivers/character/serial.rst

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=====================
Serial Device Drivers
=====================
- ``include/nuttx/serial/serial.h``. All structures and APIs
needed to work with serial drivers are provided in this header
file.
- ``struct uart_ops_s``. Each serial device driver must
implement an instance of ``struct uart_ops_s``. That structure
defines a call table with the following methods:
- ``int uart_register(FAR const char *path, FAR uart_dev_t *dev);``.
A serial driver may register itself by calling
``uart_register()``, passing it the ``path`` where it will
appear in the :ref:`pseudo file system <file_system_overview>` and it's
initialized instance of ``struct uart_ops_s``. By convention,
serial device drivers are registered at paths like
``/dev/ttyS0``, ``/dev/ttyS1``, etc. See the
``uart_register()`` implementation in ``drivers/serial.c``.
- **TTY_LAUNCH** this depends on ``CONFIG_TTY_LAUNCH``, this feature
allow user launch a new program with a special char input.
e.g. use ctrl+R to start a nuttx shell.
e.g. use ctrl+E to start user entry.
You can use ``TTY_LAUNCH_CHAR`` to customize which special char.
You can choose launch method:
``TTY_LAUNCH_ENTRY`` or ``TTY_LAUNCH_FILE``,
If``TTY_LAUNCH_ENTRY`` you can set program entry by ``TTY_LAUNCH_ENTRYPOINT``.
If``TTY_LAUNCH_FILE`` you can set file path by ``TTY_LAUNCH_FILEPATH``.
Also, you can customize:
``TTY_LAUNCH_ARGS`` ``TTY_LAUNCH_PRIORITY`` ``TTY_LAUNCH_STACKSIZE``
- **User Access**. Serial drivers are, ultimately, normal
`character drivers <#chardrivers>`__ and are accessed as other
character drivers.
- **Examples**: ``arch/arm/src/stm32/stm32_serial.c``,
``arch/arm/src/lpc214x/lpc214x_serial.c``,
``arch/z16/src/z16f/z16f_serial.c``, etc.