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Advanced User Guide

Serial Port and MAVLink Configuration

The PX4 firmware on FlyCore FC binds MAVLink instances to physical TELEM ports through MAV n CONFIG and sets each port's baud rate through the corresponding SER TELn BAUD parame…

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The PX4 firmware on FlyCore-FC binds MAVLink instances to physical TELEM ports through MAV_n_CONFIG and sets each port's baud rate through the corresponding SER_TELn_BAUD parameter. The flight controller's baud rate must match that of the external device.

Configuration principles:

Parameter names, port mappings, and default values are subject to the parameter page of the current PX4 firmware. Export the parameters before making changes. After making changes, save the parameters, restart the system, read the parameters back, and verify the link.

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Standard TELEM Mapping

Physical Port Default Function Core Parameter Default Baud Rate Device Node
TELEM1 Primary telemetry link / data transmission MAV_0_CONFIG = TELEM1 57600 /dev/ttyS0
TELEM2 Visual positioning / VIO input MAV_1_CONFIG = TELEM2 115200 /dev/ttyS1
TELEM3 Computer / planning and control MAV_2_CONFIG = TELEM3 or UXRCE_DDS_CFG = TELEM3 921600 /dev/ttyS3

When the physical wiring changes, update both the MAVLink instance mapping and the baud rate of the target TELEM port. The same port must not be assigned to both MAVLink and DDS. When using MAVLink, disable DDS on that port, and vice versa.

Migrating a TELEM Port

Prerequisites

Before migration, record:

  1. The physical port to which the device is currently connected;
  2. The target port to which the device will be migrated;
  3. The communication baud rate of the external device;
  4. Whether the target port is already in use by another function;
  5. The number of the MAVLink instance to be migrated.

Export the current parameters first, and do not assign conflicting communication functions to the same TELEM port.

Procedure

The following example migrates the visual positioning link from TELEM2 to TELEM3. The original configuration is:

MAV_1_CONFIG = TELEM2
SER_TEL2_BAUD = 115200

After reconnecting the cable to TELEM3, change the configuration to:

MAV_1_CONFIG = TELEM3
SER_TEL3_BAUD = 115200

Save the parameters and restart the flight controller. Power-cycle or restart the external device as well.

  • The parameters have been saved, and the values read back after restart match the target configuration;
  • The external device has been power-cycled;
  • The corresponding data is visible in QGC;
  • A continuous data stream is present on the computer or peripheral side;
  • There are no port assignment conflicts or baud rate mismatches.

The migration is successful when both QGC and the external device continuously receive the expected data and PX4 reports no serial port conflicts or communication errors.

Warning:

The link will be unavailable if only the cable is migrated without updating MAV_n_CONFIG, or if the baud rates at both ends do not match. For an overview of port functions, see FlyCore Port Description. For the connector pinout, see Appendix: FlyCore-FC Ports and Pin Definitions.