VOXL2 - rebooting external flight controller over MAVLink

[Patrick Hinchey]

Hi,

As far as I can tell, when I command a reboot with QGC, nothing happens. We have a Pixhawk 4 as the external flight controller plugged into the Pixhawk's USB port through the ModalAI LTE hat.

Can anyone comment on this?

Thanks!
Patrick

[modaltb]

Hi @Patrick-Hinchey

You need to use a UART, we don't have MAVLink over USB.

Please see here for a few options: https://docs.modalai.com/voxl2-external-flight-controller/

Thanks!!
Travis

[Patrick Hinchey]

@modaltb I got MAVLink over USB working by modifying line 66 of voxl-mavlink-server/src/qrb5165_interface.c. And everything else seems to be working smoothly. If I use UART, will Pixhawk reboot over MAVLink work?

[modaltb]

Yes, in my setup rebooting PX4 running on the STM32 via MAVLink (though the UART) has worked as expected. From QGC over an IP network, through VOXL2 to the external flight controller, I can reset the Flight Core in my use case.

---

As for USB, what USB device are you opening? I've only used UARTs for this so I'm curious.

As for line 66, we have 3 applications processor UARTs on VOXL2, and there's a config file (/etc/modalai/voxl-mavlink-server.conf) exists where you can specify 0, 1 or 2 for px4_uart_bus

https://gitlab.com/voxl-public/voxl-sdk/services/voxl-mavlink-server/-/blob/master/src/config_file.h#L42

These are then dev/ttyHSX values (0, 1 and 2) are specified here: https://docs.modalai.com/voxl2-linux-user-guide/#uarts

So hopefully you can just use the config file without the need to modify source (unless you are doing something with USB in which case if you can share that's awesome!)

[Patrick Hinchey]

Oh, that's cool. I thought I needed a UART daughter board. I'll give it a go through the RC expansion port.
We have a 4G LTE board plugged in to J3, and I'm using one of its USBs currently - the other has a WiFi module.
Our aircraft is designed to not be touched for months at a time, so one of the things I like about plugging the flight controller into USB is that we could flash new firmware remotely if we wanted (unless you can do that over Telem1 too? I've never tried).

[modaltb]

Hey @Patrick-Hinchey on VOXL2, that RC port is connected to a DSP which you can't get access to easily at this point, so an add-on is recommended...

This is a small one that gets you a an apps proc UART:
https://docs.modalai.com/voxl2-usb3-uart-add-on-datasheet/#j3---uart

Shown in use here:
https://docs.modalai.com/voxl2-external-flight-controller/#summary

[Patrick Hinchey]

Oh, but that uses the same plug as the LTE modem. How about the GPS connector?

[modaltb]

Negative.... besides a camera group connector that you'll need level shifting, I'd say here's your two choices:

Using the 5g modem add carrier board "M0090", which brings a UART out:
https://docs.modalai.com/voxl2-external-flight-controller/#using-m2-5g-modem-addon-board-m0090

Or the little usb3/uart add-on "M0125" as previously mentioned:
https://docs.modalai.com/voxl2-external-flight-controller/#using-usbuart-addon-board-m0125

We do have a camera group UART, but it needs level shifting (native 1.8V), and need to do some surface mount soldering (nothing too bad though):
https://docs.modalai.com/voxl2-external-flight-controller/#using-j8-camera-connector

[Patrick Hinchey]

Hmm, it looks like none of those options are available to our configuration, so we will have to stick with USB through the 4G carrier.
I've found that the Pixhawk is rebooting now (not sure if something changed, or if I'm going crazy) but voxl-mavlink-server fails, and continues to fail if I systemctl restart voxl-mavlink-server so I have to reboot the voxl2 with every Pixhawk reboot.
Not that big of a deal. Has the bug been fixed where sudo reboot takes a couple of minutes to actually reboot the VOXL2? Each time I want to reboot the Pixhawk it's about a 5 minute process