Linux/OMAP-L137: Use NAND flash and LCD at the same time.

stephan james

Part Number: OMAP-L137

Tool/software: Linux

Based on below pictures on the menuconfig ,the UI Board choice includes LCD and Nand Flash and Nor Flash which only one can be select.

After search in TI site I find below links. It seems we can configure the kernel to have LCD and NAND flash with change source code.

e2e.ti.com/.../125012 (Omap-L137 MMC/SD and EMIFA NAND FLASH multiplexing)

https://e2e.ti.com/support/dsp/omap_applications_processors/f/42/t/12347?tisearch=e2e-quicksearch&keymatch=OMAP-L137%20Nand%20&%20LCD%20Driver (OMAP-L137 Nand & LCD Driver)

First question : Are you think this case is correct?

Second question: How we can configure the kernel(PINMUX,...) to have LCD and NAND flash?

Regards

stephan james

over 8 years ago

0 Dwarakesh Radhakrishnan over 8 years ago

Guru 13660 points

Hi Stephan,

In your previous post ( e2e.ti.com/.../588839 ), I missed out to note the pins are multiplexed. From the pin muxing, it looks it is not possible to make LCD and NAND work together, since they share the same pins and there are no other pin balls for conflicting pins between LCD and NAND.

Regarding the post answer e2e.ti.com/.../12347 , it is given under the assumption that root filesystems is not from NAND. uboot configures the NAND and boots the kernel and puts in RAM. Once the kernel is up, it can configure the LCD and use. But if the filesystems are stored in NAND, then it is not possible to access filesystems and LCD at the same time.

But the workaround would be, as suggested in ( e2e.ti.com/.../125012 , when accessing LCD, you can write a code to configure the pins for LCD and when accessing the NAND, you can configure pins for NAND. This piece of code needs to be added and the successful working of both LCD and NAND will not be guaranteed to work normally(it could affect performance and hinder both LCD and NAND working together), since it is not a standard way to change pin mux dynamically, that too for interface like LCD and NAND(which stores filesystems and can be accessed very frequently).

So, I would say it is better to assume they cannot work together.

0 stephan james over 8 years ago in reply to Dwarakesh Radhakrishnan

Prodigy 40 points

Hi Dwarakesh

Based on below text.It seems there aren't conflict between LCD and NAND Flash.if this is correct now we can use LCD and NAND together?

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e2e.ti.com/.../125012

Hi Tommy,

Thanks for your reply. Nand flash use only EMA_D0-7 and EMA_A1-2 while LCD use EMA_BA0,EMA_BA1,EMA_A0,A3-A12,and EMA_D8-15. According to Pin Multiplexing Control register, shouldn't every EMIFA pin has individual mux instead of whole EMIFA muxing with LCD controller?

Peter

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Peter,

You are correct. You should be able to select PINMUX functions for each individual pin and use both LCD and NAND at the same time. It's possible that this was overlooked when the software was developed.

-Tommy

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Regards

Stephan James

0 Dwarakesh Radhakrishnan over 8 years ago in reply to stephan james

Guru 13660 points

Hi Stephan,

Yes, it is possible to interface both LCD and NAND. I was wrong, I assumed NOR hardware connection, instead of NAND. It is possible for NAND and LCD to co-exist, since NAND does not require Address lines. But LCD and NOR cannot co-exist since NOR requires both address lines and data lines(in which case it will conflict with the LCD pins). My above answer holds true for NOR and not for NAND.

0 Dwarakesh Radhakrishnan over 8 years ago in reply to Dwarakesh Radhakrishnan

Guru 13660 points

Hi Stephan,
One more point. It is fine to interface 8-bit NAND, but there will be conflict with 16-bit NAND with the LCD interface

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Linux/OMAP-L137: Use NAND flash and LCD at the same time.