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H-RTK Unicore UM982 Setup & Getting Started (PX4)
Connection to Autopilot
Various JST-GH cables are provided to attach to the UM982 10-pin JST-GH connector. Two are full 10-pin wire cables (short and long) for connecting to Pixhawk Standard Autopilot’s GPS1 connector, or similar, and provide full functionality, including a safety switch button and LED.
The 10Pin – 6Pin cable allows users to connect the UM982 to the GPS2 port on Cubepilot and Holybro Autopilots.
UM982 Ultralight
UM982 Ultra light comes with an 8-pin JST-GH connector with two adaptor cables for 10-pin and 6-pin GPS ports.
PX4 Configuration
Port Setup
The Unicore module sends the NMEA messages with some proprietary Unicore sentences. The serial baud rate is 230400.
The following PX4 parameters must be set:
SER_GPS1_BAUD -> 230400
GPS_1_PROTOCOL -> 6: NMEA
Note that the above parameters assume you are connected to GPS 1. If you are using another port, you will have to use its parameters to configure the baud rate and protocol.
GNSS Data Filtering
Set the following parameters to decrease drifting caused by fluctuation from the GNSS reading
EKF2_GPS_P_NOISE = 1
EKF2_GPS_V_NOISE = 0.6
Enable GPS Heading/Yaw
UM982 Ultralight does not support GPS heading/yaw due to its single antenna design.
The Unicore module comes with two antennas, a primary (right connector) and a secondary (left connector) antenna, which can be used to get yaw from GPS. You will need to set the following parameters:
EKF2_GPS_CTRL: Set bit 3 (8) to enable dual antenna heading into the yaw estimation.
GPS_YAW_OFFSET: Set the heading offset to 0 if the primary antenna is in the front. The angle increases clockwise, so set the offset to 90 degrees if the primary(master) antenna is on the right side of the vehicle, and the secondary(slave) antenna on the left side.
RTK Corrections
RTK works the same way as uBlox F9P modules. RTCMv3 corrections as sent by QGroundControl from an RTK GPS base station are consumed by the Unicore module, which should then change the fix type to RTK float or RTK fixed.
Advanced Application
For a guide on Advanced applications with Unicore Uprecise Software, please see the link below.
Advanced Application (Unicore Uprecise)To reset to the factory default setting, please see the link below
Factory Setting and COM Port Allocation