PX4 Instructions

Find most up to date documentation at https://docs.px4.io/main/en/dronecan/ark_gps.html

Hardware Setup

Wiring

The ARK GPS is connected to the CAN bus using a Pixhawk standard 4 pin JST GH cable. For more information, refer to the CAN Wiring instructions.

Mounting

The recommended mounting orientation is with the connectors on the board pointing towards the back of vehicle.

The sensor can be mounted anywhere on the frame, but you will need to specify its position, relative to vehicle center of gravity, during PX4 configuration.

Firmware Setup

ARK GPS runs the PX4 DroneCAN Firmware. As such, it supports firmware update over the CAN bus and dynamic node allocation.

ARK GPS boards ship with recent firmware pre-installed, but if you want to build and flash the latest firmware yourself see PX4 DroneCAN Firmware > Building the Firmware.

• Firmware target: ark_can-gps_default

• Bootloader target: ark_can-gps_canbootloader

PX4 Configuration

You need to set necessary DroneCAN parameters and define offsets if the sensor is not centered within the vehicle. The required settings are outlined below.

INFO

The ARK GPS will not boot if there is no SD card in the flight controller when powered on.

Enable DroneCAN

In order to use the ARK GPS board, connect it to the Pixhawk CAN bus and enable the DroneCAN driver by setting parameter UAVCAN_ENABLE to 2 for dynamic node allocation (or 3 if using DroneCAN ESCs).

The steps are:

• In QGroundControl set the parameter UAVCAN_ENABLE to 2 or 3 and reboot (see Finding/Updating Parameters).

• Connect ARK GPS CAN to the Pixhawk CAN.

Once enabled, the module will be detected on boot. GPS data should arrive at 10Hz.

DroneCAN configuration in PX4 is explained in more detail in DroneCAN > Enabling DroneCAN.

Sensor Position Configuration

If the sensor is not centered within the vehicle you will also need to define sensor offsets:

• Enable GPS yaw fusion by setting bit 3 of EKF2_GPS_CTRL to true.

• Enable UAVCAN_SUB_GPS, UAVCAN_SUB_MAG, and UAVCAN_SUB_BARO.

• Set CANNODE_TERM to 1 if this is that last node on the CAN bus.

• The parameters EKF2_GPS_POS_X, EKF2_GPS_POS_Y and EKF2_GPS_POS_Z can be set to account for the offset of the ARK GPS from the vehicles centre of gravity.