Cannot get the control attributes

[N7YKW]

I am getting "Cannot get the control attributes /dev/ttyAMA0 " in the MMDVM log followed by "MMDVMHost-20240126_PS4 exited on receipt of an unknown signal"

I assume this means I have bricked the modem, is there a way to recover it?

Thanks for the help,
Jeffrey

[ns2b]

I don't know how to fix it - but I had the same thing happen to my DStar and DMR hotspots.

I had upgraded both of them to 4.2.0. To create the problem go to the configuration screen
and make an edit. Just about anything does it. On my DStar hotspot I changed english_uk to english_us.
On my DMR hotspot I had enabled DumpTAData. The end result was an error as you describe.

What's going on under the hood is /dev/ttyAMA0 becomes a link to /dev/pts/0.

I don't know how to undo that.

Bob, NS2B

[N7YKW]

Thanks Bob, based on that I tried a fresh load and sure enough it lives... You are correct, /dev/ttyAMA0 becomes a link to /dev/pts/0. In my case it happened when I switched from simplex to full duplex. I was running 4.3.0.

Thanks again!
Jeffrey

[N7YKW]

It is fixed by doing:

sudo rm /dev/ttyAMA0
sudo mknod /dev/ttyAMA0 c 204 64
sudo chown root:dialout /dev/ttyAMA0
sudo chmod 660 /dev/ttyAMA0


this recreates the device file and sets ownership and permissions.

Hope this help someone else

Jeffrey

[MW0MWZ]

I added some extra checks around NextionDriver (I think that is actually the cause in this case)
So it should not happen any more after an update.

[G0FHM]

With 4.3.0 I have the problem every single time I reboot!

I've set up a cron job to deal with it.

@reboot sleep 35 && rpi-rw
@reboot sleep 40 && sudo rm /dev/ttyAMA0
@reboot sleep 45 && sudo mknod /dev/ttyAMA0 c 204 64
@reboot sleep 50 && sudo chown root:dialout /dev/ttyAMA0
@reboot sleep 55 && sudo chmod 660 /dev/ttyAMA0
@reboot sleep 60 && sudo pistar-update

I've thrown in the update command at the end to reload the pistar services and bring things back up!

J

[oh2th]

Seems all be related to bluetooth taking the device.

In /boot/config.txt search for dtoverlay and disable the bluetooth.

Code: Select all

# Dissable Pi3 Bluetooth (so that UART works)
dtoverlay=disable-bt

This will fix it and no need scheduled scripts with reboots.