bluetooth needs to be disabled on Pi3 for the UART to work properly about rpanion-server

[stephendade]

Is there any reason you can't enable the uart via the enable_uart=1 dtoverlay?

[altmattr]

I was using a pre-built image and it just wasn't working. The same image had worked perfectly on a Pi2 but that had no wifi so I had to upgrade to the Pi3 I found lying around. I was getting some packets through, but it was not working right. Then I remembered that on the pi3 the bluetooth uses the same serial so you get junk in the stream. I added the extra overlay and suddenly everything was perfect. I have to put in this overlay on every Pi3 when I try to use a UART terminal on GPIO or I get junk appearing on that terminal as well.

[altmattr]

but the subtleties of what each boot config.txt does is beyond me

[stephendade]

Is that a Pi 3B or 3B+?

I've got a 3B+ here, and the enable_uart=1 works fine for assigning /dev/serial0 to GPIO14/15 on the Pi

[altmattr]

I'll try that myself then next time I get the chance, which will be sometime next week. Do you think that boot option might do more than the equivalent raspi-config line (which is already in your deployment script)?

[stephendade]

Do you think that boot option might do more than the equivalent raspi-config line (which is already in your deployment script)?

The sudo raspi-config nonint do_serial 2 does indeed add the enable_uart=1 to /boot/config.txt, plus disables the console on that port.

[altmattr]

this page https://www.circuits.dk/setup-raspberry-pi-3-gpio-uart/ seems to explain the behaviour I see.

[altmattr]

I've done a test from scratch and I can confirm that on my pi3, using a pi connect lite the extra overlay is required

Without it you get a low byte rate and no packets. With it you get working telemetry.

For this test I used a clean pios lite, cloned the repo, used the scripts to setup and then connected to the flight controller

[stephendade]

Thanks for looking into that.

I've just tested here with a Pi 3B, Rpanion-Server 0.9.0 disk image and Pi-Connect Lite. No telemetry issues at 115200 baud.

Are you running any additional devices or software on the Pi?

[altmattr]

Mine is a Pi 3B+, perhaps that is the difference. The issue is there on all my Pis (which were all purchased in one hit a few years ago) have this issue when I am using the GPIO for console as well.

No extra hardware or software. I am starting to wonder if only a certain run of Pi3 have this issue.

[stephendade]

Mine is a Pi 3B+, perhaps that is the difference. The issue is there on all my Pis (which were all purchased in one hit a few years ago) have this issue when I am using the GPIO for console as well.

I've checked my 3B+ with no issues there either.

Is the bluetooth on the Pi attempting to connect to something? Might be worth trying with the bluetooth disabled.

[stephendade]

I've added a note to the documentation (https://www.docs.rpanion.com/software/rpanion_server_v09#flight_controller), in case other users come across this issue.