Lightware GRF250/GRF500 Gimbal Lidar

LightWare GRF250 and GRF500 are small and light Lidar modules with a range of 250m and 500m, respectively.

INFO

The Lidar driver is not included in the default build of PX4. You will need to create and use a custom build.

Where to Buy

Order these modules from:

• GRF250
• GRF500

Hardware Setup

The rangefinder can be connected to any unused serial port, such as TELEM2. Parameter Configuration explains how to configure the port to use and the other properties of the rangefinder.

PX4 Setup

Add the Driver to the PX4 Build

The lightware_grf_serial driver for this Lidar is not included in PX4 firmware by default. In order to use these modules you will first need to update the firmware configuration to add the driver, and then build the firmware.

1. Update the firmware configuration. You can use either of the following options:

   • Menuconfig:

     1. Install and open menuconfig
     2. In menuconfig, navigate to Drivers > Distance sensors
     3. Select/Enable lightware_grf_serial
     4. Save the configuration

   • Manually update default.px4 to include the configuration key:

     1. Open the default.px4board config file that corresponds to the board you want to build for. For example, to add the driver to fmu-v6x boards you would update /boards/px4/fmu-v6x/default.px4board

     2. Add the following line and save the file:

        CONFIG_DRIVERS_DISTANCE_SENSOR_LIGHTWARE_GRF_SERIAL=y

2. Build PX4 for your flight controller target and upload the new firmware.

Parameter Configuration

You will need to configure PX4 to indicate the serial port to which the sensor is connected (as per Serial Port Configuration) and also the orientation and other properties of the sensor.

The parameters to change are listed in the table.

Parameter	Description
SENS_EN_GRF_CFG	Set to the serial port the sensor is connected to.
GRF_UPDATE_CFG	Set the update rate.
GRF_SENS_MODEL	Set the update rate.

Testing

You can confirm that the sensor is correctly configured by connecting QGroundControl, and observing that DISTANCE_SENSOR is present in the MAVLink Inspector.

Moving the sensor around at various distances from a surface will have the current_distance value change.

Troubleshooting

If you are having problems with connecting to the sensor you may need to unassign a the default serial port. Unassign Default Serial Port