Pixhawk 4 unable to complete serial connection with MicroXRCEAgent

[CannonFodder511]

Describe the bug

I am running a connection from a Pixhawk 4 running firmware 1.14.0. It is connected via a serial connection to a raspberry pi running Jammy and ROS 2 humble. This runs eProsima's MicroXRCEAgent.

Things I've tried:

• There is nothing else trying to use the Telem 2 port on the Pixhawk.
• I am able to run mavproxy.py over the Telem 2 port
• A loopback script confirms the port is usable.

What else can I try to debug this?

Mavlink output: `nsh> uxrce_dds_client start -t serial -d /dev/ttyS2 -b 115200

nsh> uxrce_dds_client status

INFO [uxrce_dds_client] Running, disconnected

INFO [uxrce_dds_client] Using transport: serial`

Pi Output: `/ros_ws: MicroXRCEAgent serial --dev /dev/ttyUSB0 -b 115200 -v6

[1709157626.383849] info | TermiosAgentLinux.cpp | init | running... | fd: 3

[1709157626.385726] info | Root.cpp | set_verbose_level | logger setup | verbose_level: 6`

To Reproduce

Setup according to this page: https://docs.px4.io/main/en/companion_computer/pixhawk_rpi.html Run "uxrce_dds_client start -t serial -d /dev/ttyS2 -b 115200" on the Pixhawk 4 over mavlink Run "MicroXRCEAgent serial --dev /dev/ttyUSB0 -b 115200 -v6" on the Pi

Expected behavior

Pi and PX4 should connect, the PX4 posting topics to the XRCE Agent

Screenshot / Media

No response

Flight Log

Mavlink output: nsh> uxrce_dds_client start -t serial -d /dev/ttyS2 -b 115200 nsh> uxrce_dds_client status INFO [uxrce_dds_client] Running, disconnected INFO [uxrce_dds_client] Using transport: serial

Pi Output: /ros_ws: MicroXRCEAgent serial --dev /dev/ttyUSB0 -b 115200 -v6 [1709157626.383849] info | TermiosAgentLinux.cpp | init | running... | fd: 3 [1709157626.385726] info | Root.cpp | set_verbose_level | logger setup | verbose_level: 6

Software Version

1.14.0

Flight controller

Pixhawk 4

Vehicle type

None

How are the different components wired up (including port information)

No response

Additional context

No response

[mrpollo]

Make sure you there's nothing else running on the same port, it's either MAVLink or DDS the link can't handle both

[CannonFodder511]

Make sure you there's nothing else running on the same port, it's either MAVLink or DDS the link can't handle both

Is there any way to do this besides the parameters on QGC? All the mavlink parameters are set to disabled

[chutsu]

1. Are you sure you swapped the serial RX / TX?

2. Dialout permissions on the Pi?

[CannonFodder511]

I followed the guide for the connections but did try swapping. Dial out permissions are enabled for the user and root

[chutsu]

Also couple other things.

• You haven't told us what RPi you're using
• Why are your baud-rates different to the defaults?
• Also the guide you linked shows you how to connect RPi GPIO UART to TELEM 2, yet in your RPi you are launching the agent on port /dev/ttyUSB0? (MicroXRCEAgent serial --dev /dev/ttyUSB0 -b 115200 -v6), should this not be /dev/ttyAMA0 or /dev/serial0
• Have you tried simply communicating to TELEM2 as a MAVLink connection? (not using the USB port of the Pixhawk)

[Geol-23]

Hello, I am having the same issue. I'm using a Raspberry Pi 4 (22.04) to communicate with an mRo Pixhawk (1.14.3). I've followed the guide and installed the agent as a standalone on the Pi, I've used the reccommended baud rates and ports (921600, TELEM2 on the FC and UART0 on the Pi) and I believe the pins are the correct way around. I've also added the dialout permissions and I'm pretty sure nothing else is running on that port.

To diagnose this I've tried to boot up another FC (same version as the main FC) and the issue persists. I've established communication using mavproxy according to the guide.

I am getting the same logs per the issue. Any help is appreciated. Cheers.

[mrpollo]

@Geol-23 please open a new issue