# Making Serial Port Drivers User-Configurable

This topic explains how to set up a serial driver so that it can be end-user configured (via parameters) to run on any of a flight controller board's configurable serial ports.

## Preconditions

The driver is assumed to already exist, and be started in the shell using the command syntax:

<driver_name> start -d <serial_port> [-b <baudrate> | -b p:<param_name>]


where,

• -d: serial port name.
• -b: Baud rate (optional) if the driver supports multiple baud rates. If supported, the driver must allow you to specify the rate as both a bare baudrate and as a parameter name in the form -b p:<param_name> (which can be parsed with px4_get_parameter_value()).

See the gps driver for an example.

## Making the Driver Configurable

To make driver configurable:

1. Create a YAML module configuration file:
• Add a new file in the driver's source directory named module.yaml
• Insert the following text and adjust as needed:
module_name: uLanding Radar
serial_config:
- command: ulanding_radar start -d ${SERIAL_DEV} -b p:${BAUD_PARAM}
port_config_param:
name: SENS_ULAND_CFG
group: Sensors


The full documentation of the module configuration file can be found in the validation/module_schema.yaml file. This is also used to validate all configuration files in CI.

2. Add the module configuration to the CMakeLists.txt file for the driver module:
px4_add_module(
MODULE drivers__ulanding