Resolve Unresponsive Firmware Upload on Pixhawk Boards with Separate Bootloader Port

R2026b

Issue

Some Pixhawk® boards use separate COM ports for bootloader communication and main MAVLink communication. When you connect such a board, the bootloader port appears briefly in Device Manager and then switches to the main communications port after a few seconds.

Device Manager showing the bootloader COM port appearing briefly and then switching to the main communications COM port

Firmware upload requires the bootloader COM port. If you specify the main communications port instead, the upload does not proceed and the Hardware Setup window stops responding.

Hardware Setup window showing an unresponsive firmware upload when the wrong COM port is selected

Possible Solutions

Identify the Bootloader and Communications COM Ports

Determine which COM port corresponds to the bootloader and which corresponds to main communications.

  1. Disconnect the Pixhawk hardware from your computer.

  2. Open Device Manager.

  3. Connect the Pixhawk hardware to your computer.

  4. Note the COM port that appears first. This is the bootloader COM port.

  5. Wait approximately five seconds. The device disappears from Device Manager as it transitions from bootloader to main PX4® firmware.

  6. Note the COM port that appears after one to two seconds. This is the main communications port.

Upload Firmware Using the Correct COM Ports

Use the bootloader COM port for firmware upload and the communications COM port for MAVLink communication.

  1. In the Test Connection step of the Hardware Setup, set Host Serial Port for upload to Specify Serial Port.

    Test Connection step with the Specify Serial Port option selected

  2. Replace Enter Upload Port with the bootloader COM port value.

    Enter Upload Port with COM5 entered as the bootloader port

  3. Disconnect the Pixhawk board and reconnect it to the host computer.

  4. Click Upload Firmware immediately after reconnecting the board. When the dialog box prompts you to disconnect and reconnect the board, do so, then click OK to start the upload.

    If the upload does not start, disconnect and reconnect the board again.

  5. After the firmware uploads successfully, replace Enter Communication Port with the main communications COM port value. Then, click Get Accelerometer data to verify the connection.

    Hardware Setup window showing the communications COM port entered and the Get Accelerometer data button

  6. Set the COM ports for upload and communication in the Simulink® model, and then deploy the model on the Pixhawk hardware.

See Also

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