i.mx53 qsb additional uart use

[mouha]

Hi,

I'd like to use 1 or 2 additional uart on i.MX53 QSB  that is (are) not the Debug Uart on Linux (Yocto)

am I obliged  to use those on J13 (26-28-32-34) as it seems they are use elsewhere ?.

[mouha]

As an example from my previous question : I'd choose J13 pins 26 & 28 for uart_Txd_mux & uart_rxd_mux : are they availabel right away to use from Yocto ?

[OtavioSalvador]

It is not related to Yocto but your kernel. You'll need to change the MUX in the kernel/bootloader.

[mouha]

Otavio,does it relies to chap 4 in the System Development User’s Guide ?

As I never did such things I'm not sure to understand the main point of this tool as it save to xml.

[OtavioSalvador · Accepted solution]

The real thing here is not Yocto specific as you have to prepare the patches to Kernel and U-Boot.

Once you have those done, you should make a customer/project specific layer and add a board for you. After that add overridies to Kernel and U-Boot applying your patches so it is maintainable in future releases.

Check at http://www.yoctoproject.org/docs/current/mega-manual/mega-manual.html

• 1.2.6. Hardware Configuration Options
• 1.4. Customizing a Recipe for a BSP
• 7.14. Building kernels - kernel.bbclass

I think this gives you an idea.

[mouha]

Thanks Otavio, now I understand that :

to have the i.MX53QSB using uart4 3 (or else) I have to modify kernel via kernel patch(es) .

[mouha]

Can anybody help me ? :

from the Development user's guide it seems that I need to use IOMUX to change the i.MX53 QSB to have additional UART on the board (p169). Did I get it cleary or I can use any UART (not app one for sure) right away form the J13 ?

[OtavioSalvador]

I think you can enable support for the APP UART in the kernel config. It should work, no?

[mouha]

Hi Otavio,

can you precise what is the "App UART" on the board please ?

[OtavioSalvador]

Right David, it is not available in the board.

In this case I think you'll really need to plug it in J13. But I think you'll also need to change the board file to enable it.

[mouha]

OtavioSalvador a écrit:

In this case I think you'll really need to plug it in J13. But I think you'll also need to change the board file to enable it.

Ok, I assume that this "board file" is about the I/O definition. Thanks.

Nevertheless, I'm really surprised that from all the 5 UARTs not anyone can be accessed easier.