TTGO T-Beam GPS problem

[Dolqus]

1. Stratux version: 1.6r1-eu026

2. Stratux config: default

   SDR

   • single
   • dual

   GPS

   • yes
   • no
     type: TTGO T-Beam v1.1 ublox NEO-M8N

   AHRS

   • yes
   • no

   power source: 3A 5V power supply

   usb cable: tested with two different cables (which both work)

3. EFB app and version: (e.g., WingX Pro7 8.6.2)
   not relevant
   EFB platform: (e.g., iOS 9.2)
   not relevant
   EFB hardware: (e.g., iPad Mini 2)
   not relevant

4. Description of your issue:
   Stratux does not receive TTGO T-Beam GPS NMEA signals, at the website is written "GPS hardware: Serial port (not communicating).
   I also tried it with a different raspberry pi, nothing connected but the T-Beam and the same issue appears.
   T-Beam GPS tested and working.
   The T-Beam connects as serial device on ttyACM0 but it has a baud rate of 115200, so the NMEA text is only shown with
   cat /dev/ttyACM0 after doing stty -F /dev/ttyACM0 115200.
   Is there a way to tell stratux to listen at /dev/ttyACM0 with a baud rate of 115200?
   (Logs are made on a fresh flashed version)
   If possible, enable "Replay Logs", reproduce the problem, and provide a copy of the logs in http://192.168.10.1/logs/stratux/ and http://192.168.10.1/logs/stratux.lo
   stratux.log
   syslog.txt
   PS: What does "raspberrypi gen_gdl90[542]: mean: Length too short" mean?

[b3nn0]

Stratux will autodetect the baud rate. It will also try 115200. "Serial port (not communicating)" would mean that your T-Beam isn't found at all - so Stratux falls back to the PI's UART pins. The Stratux process looks for /dev/serialin, which is symlinked to your T-Beam by udev (/etc/udev/rules.d/10-stratux.conf). Are you missing that file? Does /dev/serialin exist (I'd assume it doesn't)?

You can ignore the Length too short debug message. It will disappear once we have GPS Data.

[Dolqus]

Hi b3nn0,
yes, /dev/serialin does not exist and the serial ports are linked this way in /dev/:
serial0 -> ttyAMA0
serial1 -> ttyS0

[b3nn0]

Does your /etc/udev/rules.d/10-stratux.conf exist/is it correct (like this: https://github.com/b3nn0/stratux/blob/master/image/10-stratux.rules )? Because that's the one that causes /dev/serialin to exist.
What does lsusb say? Maybe unplug your T-Beam, then run "udevadm monitor" and plug it back in to see more detail on what happens.

EDIT: Did you try to compile Stratux on a plain RaspiOS image? Or did you flash a recent Stratux image? Because if you tried to roll your own, the process is much more complicated than just running make install. There is a lot of OS setup happening, of which at least quite a bit is required for things to work correctly.
See here: https://github.com/b3nn0/stratux/blob/master/image/mk_europe_edition_device_setup64.sh

[Dolqus]

yes, 10-stratux.conf does exist and is correct.
lsusb says following:

Bus 001 Device 006: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
Bus 001 Device 005: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T
Bus 001 Device 004: ID 1a86:55d4 QinHeng Electronics
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. SMC9514 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
(the T-Beam is Bus 001 Device 004: ID 1a86:55d4 QinHeng Electronics)

udevadm monitor does say this:

monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent

KERNEL[884.366054] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2 (u sb)
KERNEL[884.366968] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.0 (usb)
KERNEL[884.368214] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.0/tty/ttyACM0 (tty)
KERNEL[884.368454] bind /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.0 (usb)
KERNEL[884.368607] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.1 (usb)
KERNEL[884.368799] bind /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.1 (usb)
KERNEL[884.368961] bind /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2 (u sb)
UDEV [884.394081] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2 (u sb)
UDEV [884.402173] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.0 (usb)
UDEV [884.405475] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.1 (usb)
UDEV [884.411830] bind /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.1 (usb)
UDEV [884.418299] add /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.0/tty/ttyACM0 (tty)
UDEV [884.427497] bind /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1- 1.2:1.0 (usb)
UDEV [884.455548] bind /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2 (u sb)
^C

I did flash the recent Stratux image, first I tried yours but obviously the results are the same.

[b3nn0]

Interesting.. Apprently TTGO changed the USB/Serial chip on the T-Beam. It always was a CP2104 - now it is a QinHeng Electronics (never heard of that one before..).

I don't have such a T-Beam, so it's hard for me to test.
Could you

• Enable persistent logging (to make sure that changes to the filesystem are actually stored on disk) and reboot
• Add this line to 10-stratux.conf:

SUBSYSTEM=="tty", SUBSYSTEMS=="usb", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="55d4", SYMLINK+="serialin"

• Reboot again

and see if it works?

Where did you purchase this T-Beam? Mind sharing a link?

[Dolqus]

correction: 10-stratux.conf does actually exist as 10-stratux.rules (hope that makes no difference)
I did buy it here: https://www.amazon.de/gp/product/B08KVZD6JK
My T-Beam was produced februrary this year.

Sadly those changes did not work, it looks like the 10-stratux.rules gets resetted every reboot

[b3nn0]

Then I think you forgot the first point: enable persistent logging in the web interface (or run overlayctl disable and reboot).
That's because of the read-only overlay root filesystem and needs to be disabled first. And yes, 10-stratux.rules is correct of course.

[Dolqus]

yes, my mistake I did not rebooted after I enabled persistent logging (too impatient :D)
and yes it works!!
Thank you very much and independent of that thanks for your work, we really appreciate!.

[b3nn0]

Cool. I'll add the line to the next version. Feel free to close this issue then (I can't since I'm not an admin of this repository)