Enabling UART A on the ODROID N2/N2+

[allanmac]

In my quest to use an ODROID N2 as a time server, I had to figure out how to enable UART_EE_A.

 

Device trees for other boards sometimes enable UART A in the base device tree but the ODROID N2/N2+ does not.

 

I am not sure why device trees don't fully define devices like UART_A and then just leave them disabled instead of partially defining them with missing "pinctrl" entries (as in the N2 device tree).

 

Anyway, I've attached `meson-g12b-odroid-uart-ee-a.dtso` as an example of how to enable UART_EE_A.

 

Additionally:

• The DT overlays for Meson UARTs (e.g. `/boot/dtb/amlogic/overlay/meson-uartA.dtbo`) are not compatible with the N2.  It's a source of confusion for new users.
• I noticed a problem in the current `armbian-config` scripting.  I originally named the overlay as `meson-g12b-odroid-uartA` but selecting it would also enable `meson-uartA`.  Probably a regexp/sed issue. 

 

 

meson-g12b-odroid-uart-ee-a.dtso

[allanmac]

The PPS (`pps-gpio` driver) overlay is attached.

meson-g12-pps-gpiox-16.dtso

[Guest]

To activate the /dev/ttyAML1 overlay I did execute the following commands:

 

dtc -O dtb -o meson-g12b-odroid-uart-ee-a.dtbo meson-g12b-odroid-uart-ee-a.dtso


mv meson-g12b-odroid-uart-ee-a.dtbo /boot/dtb/amlogic/overlay


vim /boot/armbianEnv.txt


overlay_prefix=meson
overlays=g12b-odroid-uart-ee-a

 

Is this the correct way?

 

Thank you.

[allanmac]

Yes, that looks right to me.

 

Note that I built these overlays in the Armbian build.

 

But I just compiled the .dtso locally and byte-compared it to the Armbian built overlay and they match.

 

Once you place the overlay into `/boot/dtb/amlogic/overlay` you should be able to enable it via the `armbian-config` tool or just use the `armbian-add-overlay` command which automagically adds the overlay to `/boot/overlay-user`.

 

Some more info here too.

 

 

Edited September 24 by allanmac
Typo