i.mx53 qsb additional uart use

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i.mx53 qsb additional uart use

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mouha
Contributor I

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 ?.

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OtavioSalvador
Senior Contributor II

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.

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mouha
Contributor I

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 ?

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OtavioSalvador
Senior Contributor II

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

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mouha
Contributor I

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.

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OtavioSalvador
Senior Contributor II

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.

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mouha
Contributor I

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) .

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mouha
Contributor I

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 ?

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OtavioSalvador
Senior Contributor II

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

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mouha
Contributor I

Hi Otavio,

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

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OtavioSalvador
Senior Contributor II

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.

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mouha
Contributor I

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.

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