Orange Pi Zero 2 UART connection

[Nacho Blanco]

Hello

I'm new in Armbian. I'm trying to connect one Orange Pi Zero 2 to a 3d printer (board Cheetah v1.2) using UART in order to install Klipper to control the printer. I can't find how to enable the UART port to connect. I'm planning use UART 5 (pins PH2 PH3 according to this pinout http://www.orangepi.org/orangepiwiki/images/e/e3/Orange-pi-zero2-img4.png) . I've been searching for hours the right way to enable the UART communication, but I've not found a clear explanation about how to do it. I've trying armbian-config but Hardware option doesn't appears in the Menu. I'm using the Armbian_22.11.3_Orangepizero2_bullseye_legacy_4.9.318 image.

Also, I've another question: I dont' know why but most of the images from the repository doesn't boot. The red ligth on the board never changes to green and of course i can't connect to the Opi. Why could be the reason?

Thanks

Edited April 7, 2023 by Nacho Blanco
Posted before ending the question by error.

[ALIGMSTEN]

Hello @Nacho Blanco I speak under correction, because I cant recall the 4.9 dtb from memory just at the moment, its possible that the nodes are not enabled.

 

With the edge images you should not expect the the green led to light up, we would have to submit a simple patch for that behavior. Unfortunately I've not had much time available lately to continue some work on OPIZ2, nonetheless edge images on the community support page, should be functioning as minimal cli.

 

Best of luck...

[Nacho Blanco]

Thanks for your answer. I'll search the community support page.

 

And, what about the other question? I still don't know how to enable UART connection. Anybody could help me?

 

Thank you in advance

[ALIGMSTEN]

Hello @Nacho Blanco ,I assume for the legacy images, (don't spend time with there), you would also have to add an overlay & its prefix to    /boot/armbianEnv.txt  

 

overlay_prefix=sun50i-h616
overlays=uart5

 

What I sort of recalled for uart5 is that one of the peripheral definitions is disabled

 allwinner,function = "io_disabled"

 

My understanding is this does not have any bearing other than its disabled, until you set status='okay' enabling the peripheral.

 

Edited: clarification

 

Its 'understood' that just adding the parameters to armbianEnv accomplishes nothing,

whether or not the prefix=sun50iw9/sun50i-h616 the necessary, dtb entries, folders and files must exist or be created, right?

 

Option 1: de-compile the dts and make the changes and recompile on the board (no overlay).

 

Option 2: create the overlay and add to /boot/dtb/sunxi/overlay (think that's right) then adding the parameters to armbianEnv does the dynamic loading for you (again assuming)

 

Option 3: dynamic load manually (something like this)

 

mkdir -p /sys/kernel/config/device-tree/overlays/uart5

cat uart5.dtbo > /sys/kernel/config/device-tree/overlays/uart5/dtbo

 

I'm pretty sure the legacy kernel has symbols enabled so all this should be possible for overlays.

 

Best of luck.....

[Nacho Blanco]

Thanks for the answer. 

[ALIGMSTEN]

A suggestion would be to check the status of uart on the board.

 

dmesg | grep tty*

ls -l /dev/ttyS5

ls -l /dev/ttyS*

ps -ef | grep tty

 

etc, to start with, and report.

 

If you are more specific what you have tried, a fellow member may offer assistance, should they have a working solution.