OMAPL137 SecureDigital versus NAND/NOR Flash?

Hi,

Regarding the NOR flash.

Is it possible to BOOT OMAP^L137 from 16bit NOR Flash？

The bootloader document "SPRAB04B" states that
"the bootloader configures EMIFA for
8-bit access and reads the first word from the NOR Flash"

Does this require a different settings with DSP and Flash
for the first 8 bit access?

I want to connect M29EW NOR Flash with OMAP-L137. please let me
know if you have any documents or application notes for
booting OMAP-L137 from NOR Flash and also the necessary circuit description.

Thankyou.

yes, it is possible to boot OMAP-L137 from 16-bit NOR flash; the 8-bit mode is the default, but as that same document describes "This first word indicates if the NOR Flash should be accessed in 16-bit or 8-bit mode..."

Unfortunately, I do not know of any OMAP-L137 app Note or document that describes this scenerio in more detail than the app note you are already referring to.  If you have any questions with this app note, we wil be happy to help fill in the voids

Chikku,

When booting from a 16-bit NOR device, you don't need to worry about special EMIFA connections for the initial 8-bit read.  Just connect the NOR device to EMIFA (chip select 2) in the standard 16-bit way.  The initial read will only look at the lower 8 bits of the first NOR word, but that is not a problem.  The LSB in that word will tell the bootloader to reconfigure itself in 16-bit mode before the bootloader tries to read the rest of your NOR contents.

Incidentally, the bootloader app note only describes NOR boot with AIS.  For more information on non-AIS NOR boot modes, check out this wiki page: Secondary Bootloaders on OMAP-L1x

Hope this helps.

Hi,

That solved my confusion.

Thankyou.

Hi,

I am sorry, I still have some confusion.

As you said the,initial read will only look at the lower 8 bits of the first NOR word,
what about the remaining bits (like COPY byte)? Does this mean that ,the remaining 28 bits from the NOR Config Word are ignored?

According to your statement ,"The LSB in that word will tell the bootloader to reconfigure itself in 16-bit mode before the bootloader tries to read the rest of >your NOR contents"

In this case(16-bit mode), I think the COPY byte will be ignored.

I am planning to use NOR direct BOOT mode, do you have any reference guide or procedure as such,
the link which you shown me describes the development of a secondary bootloader used for NOR legacy boot.

Thankyou and Regards.

Chikku,

Sorry, I may have misstated what happens with the first NOR word.  The bootloader will read the lowest 8 bits first to determine whether to operate in 8- or 16-bit mode.  Then, it will read the rest of the first word before continuing on to the rest of the NOR contents.

Also, the wiki page describing secondary bootloader creation can serve as instructions for a NOR direct bootloader with a few simple changes:

1. Change the linker command file to place your CFG and PROG sections at 0x60000000 and 0x60000020, respectively.
2. Change the METHOD field in the NOR config word to select NOR direct boot (0x1)
3. Change the hex utility command file such that org = 0x60000000

This should allow you to create a secondary bootloader for NOR direct boot.