Odd USB problem on RaspPi 4 with RS3D

Technical Support
1

This may well be a dumb question but I’m a bit baffled by USB behaviour of my RaspPi-4.

I have both uBLOX and GlobalSat USB GPS modules, but when I connect either of them, the associated device file (/dev/ttyACM0 or /dev/ttyUSB0) does not appear. I tried with the USB2 and USB3 ports. I’m not aware that I need to install a device driver for either GPS device, but perhaps I’m wrong. I do know both dongles are ok because they both work on Windows and Ubuntu.

It is my understanding that the associated device file should automatically show up when the RaspPi is booted. There are no other devices plugged into the USB ports. The gpsd and gpsd-clients packages are enabled but of course gpsd doesn’t have anything to connect with.

One thing odd … the lsusb command returns nothing, even when I run as root.

I’m baffled, and probably missing something obvious. This is a vanilla RS install, latest version from GitHub. Do I need to do anything special on /boot/config.txt ?

Thanks for any advice you can offer. 73, Chuck

2

Hello Chuck,

From what I read, I understand (please correct me if I’m wrong) that you are not using the GPS module you can buy in our shop (this).

If the above is correct, the possible reason why the Shake is not recognizing either module you are testing is that they are not officially supported by our OS. The main reason is the sheer variety of GPS chips, firmware, and USB/serial implementations on the market. While many can work, they often require model-specific tweaks to meet the Shake’s needs, and we can’t reliably test or maintain support for all of them.

You can find more info on this page in our manual.

If you were instead using our supported module, could you provide the logs from the Shake you’re using so we can take a more in-depth look?

3

Hello again Chuck,

A request from our software team: could you download and send us the logs from the Shake, which you are trying to connect the GPS module to?

If you haven’t already tried, does the Pi (using a new microSD card with the official Pi OS installed) see the GPS module when connected to the USB ports? Or does it not detect the device at all?

Do commands such as lsusb, dmesg | tail -20, and usb-devices return empty results in this configuration too?

Thank you.

4

Hello again, and thanks so much for your message. I am a bit late getting back to you due to serious maintenance (replacing the print head and damper valves) on a troublesome large-format Epson printer. I now have Technicolor fingers. :sweat_smile:

Funny you should ask about trying things … troubleshooting Linux and its derivatives is something I have enjoyed for years, so I’m more than happy to dig into any info the software team needs.

I was running on a 64GB uSD card that was burned with the latest compressed GitHub OS file (using the RaspPi burner app on one of the Macs), but I was thinking I should put the official RS card back and boot it to see if behaviour changes. Fortunately that’s an easy task since the steel enclosure is configured to allow easy access.

Regarding the ‘lsusb’ and ‘usb-devices’ commands, I find it very odd that they don’t return anything at all when I run as root on the 64GB card. Using the USB-2 and USB-3 ports.

Sooooooo …
I booted the original RS uSD card, booted fine and runs well, but with the same failure to report any USB devices. As a test, I connected a USB SD card adapter to one of the USB-2 ports, same problem, not detected. Just for completeness, I tried the commands both as root and as myshake, although that should make no difference since they are read-only commands.

At this point, it has become a real mystery. I am willing to believe I could have done something odd, but the original RS uSD card is unmodified other than changing root’s password. I will leave it running in case the team would like me to explore further.

As an aside, the same Pi-4 boots Ubuntu 24.04 and ‘lsusb’ and ‘usb-devices’ work as expected, so the problem seems to be somewhere in the RS configuration.

I have attached a tar file with a log report using the original RS uSD card …

RSH.RC953.2026-02-19T21_37_38.logs.tar (1.4 MB)

Anything I can do to help, just ask. My pleasure, one of the benefits of being a retired computer jock!

73, Chuck VA7UL

1 Like
5

Thank you as usual for the very detailed background about the tests you have done, and for the logs regarding this specific issue.

I’ve passed everything to our software team so that they can take a look.

I’ll update you when I have news from them.

6

Thank you for the logs and all the details! I love how deep you dive into these things.

From them, it is clear that no data is flowing across the USB ports to which you have connected the GPS module.

If you open the /opt/log/gpsd-mgr.log file, you’ll find lines like this:

No GPS device named one of ( /dev/ttyACM0 /dev/ttyUSB0 /dev/ttyUSB1 /dev/ttyUSB2 /dev/ttyUSB3 /dev/ttyUSB4 /dev/ttyUSB5 /dev/ttyUSB6 /dev/ttyUSB7 /dev/ttyUSB8 /dev/ttyUSB9 ) found, is dongle plugged in?

The next step would be investigating deeper using udev to find out what’s happening when you connect the device to the port and, if this says that the device is actually connected and recognized, you then need to cat that device to see if data is actually flowing on your screen.

From there, we can see what needs to be done to get the GPS module working, or whether we need to run other checks.

Thank you!

7

Been very busy, but today I took some time to repeat my tests just in case. Here is the procedure I followed:

  1. Using the RS official uSD card supplied with the kit:
    The ‘lsusb’ and ‘usb-devices’ commands both return absolutely nothing, I just get the shell prompt back.
    Connecting both of my USB GPS devices (one at a time), one requires /dev/ttyUSB0 the other requires /dev/ttyACM0. Neither of those device files appear when the GPS modules are connected, using both USB-2 and USB-3 ports on the Pi-4. Rebooting makes no difference.

  2. Using the 64GB uSD card burned with the latest RS software from Github:
    Exactly the same result … ‘lsusb’ and ‘usb-devices’ return nothing, and no device files are created when the GPS modules are connected.

3). Using the standard Ubuntu RaspPi based on the same distribution as the RS code, everything just works as it should. Both types of GPS module cause the correct device file to be created and produce the expected sentences from the GPS chip.

So it would appear that the USB ports are not enabled using the RS platform, but are enabled and working with the Ubuntu RaspPi platform.

Just to complete the scenario, the only change to the /boot/config.txt file is
‘arm_freq=1000’ in order to underclock from 1.5GHz down to 1GHz. Performance of RS is excellent at this clock limit, and it is my preference to underclock whenever possible.

The /opt/log/gpsd-mgr.log file shows multiple instances of exactly the same string you show in your reply. This seems to verify that USB isn’t enabled. Is there something in the /boot/config.txt file that should be added?

This Pi-4 can boot Ubuntu from a USB disk, but it is configured to prefer the uSD card first. Booting RS or Ubuntu is a flawless procedure, and it boots quickly. Other than this GPS oddity, I am completely happy with the RS. The only other quirk is that inability to have increased storage stick after it’s configured, but that is an unrelated issue being looked into separately.

If there are any other items the team would like me to explore, I am most happy to help.

73! Chuck VA7UL / VA7ULD