Troubleshooting

USB Host Port: Devices not working as intended

Since the LXA TAC can be powered via Power over Ethernet according to the 802.3af standard it’s maximum power consumption is limited to 13W. This power budget also applies if the device is powered via the 12V barrel jack.

This in turn limits the maximum amount of power and thus current that can be consumed by USB devices. To ensure uninterrupted operation of the LXA TAC regardless of the connected USB devices the maximum current is limited.

The specifics of how this USB current limit is enforced has been tweaked between the different LXA TAC hardware generations. Gen 3.1 devices and earlier are known to cause issues with some USB devices like WiFi dongles or the Linux Automation GmbH USB-Mux. We offer reworking affected devices to mitigate these issues. Contact us for more information.

See Product Identification for more details on LXA TAC releases.

Serial Debug Console

The LXA TAC provides a serial debugging console on the 2.5mm headphone jack on the front of the device. Compatible cables (TX on the tip, RX on the ring, GND on the shell) are, among other places, available in our online shop.

If you do not have such a cable at hand you can also open the case and use the pin headers directly behind the 2.5mm jack.

The serial output uses the usual 115200N8 connection parameters.

On power up you should see barebox starting, followed by a Linux boot and finally a login shell. Just type root as username and use no/empty password to log in.

Persistent Logging

Systemd journals are logged persistently and across RAUC updates. You can find them under /srv/journal/.

pstore

In case of system crashes or kernel panic the most recent log entries and backtraces may not have found their way into the regular logs, but are read from the RAM directly after the subsequent reboot.

You can find them in /var/lib/systemd/pstore/ and also attached as a file to the post-reboot journal. To access the entries in the journal, run

journalctl -b -o verbose -a -t systemd-pstore

The most recent barebox logs can also be found here.