GPMC config for NOR flash

Taahir Shamsuddin

I have a TI AM335x EVM board whose NOR Flash I would like to use in the development of drivers.
I am having trouble with my code so would like some help in sanity checking the basics...

The AM335x EVM has 16MB of NOR flash which I would like to place on CS0 with a base address of 0x0.

These are my settings -

1) AM335x EVM PROFILE
To setup the PINMUX for NOR flash and GPMC I have set the board to profile #3 using the CPLD profile switch.

2) SYSBOOT Pins - default ( I currently dont want XIP or BOOT from NOR on the EVM)

3) CS CONFIG for 16MB of flash with a base address of 0x0

   Base Address of 0x0
      I have set bits [5-0] of GPMC_CONFIG7_0 to 0x00

   Chip select mask for 16MB of NOR
      I have set bits [11-8] of GPMC_CONFIG7_0 to 0xF

So the question is are the settings for GPMC_CONFIG7_0 correct?

Thanks,
Taz

over 13 years ago

0 Steve Kipisz over 13 years ago

TI__Genius 15510 points

You cannot use a base address of zero. Typically, NOR is mapped to 0x08000000 so that GPMC_CONFIG7 has a value of 0xF48.

Steve K.

0 Taahir Shamsuddin over 13 years ago in reply to Steve Kipisz

Prodigy 60 points

Steve,

Thanks for your response,

I am a little confused maybe you can help,

My intention was to configure sysboot for 'Fast External Boot' and jump to our custom boot code sitting in NOR flash.

I was going off section 26.1.6.1 of the TRM and some other places where it states the following,

Fast Exteranal Boot "Consists of a blind jump in ARM mode to address 0x00000000 in an external XIP device connected to CS0"

but reading further on the address 0x08000000 is also mentioned.

So I suppose the real question is,

What address does the ROM code jumps to in "Fast External Boot" mode, once it has finished?

Thanks,

Taz

0 Steve Kipisz over 13 years ago in reply to Taahir Shamsuddin

TI__Genius 15510 points

The boot ROM maps NOR offset 0x00000000 to memory address 0x08000000 and jumps to 0x08000000.

Steve K.

0 Taahir Shamsuddin over 13 years ago in reply to Steve Kipisz

Prodigy 60 points

Thanks for the prompt reply,

Things are clearer now and it also explains the doubts I had trying to configure the GPMC with a base of address of zero.

Thanks Again

0 Robinson lei over 10 years ago in reply to Steve Kipisz

Intellectual 600 points

hello Steve Kipisz

why NOR is mapped to 0x08000000?

I Check the am335x data sheet and could not find 0x08000000?

Can you tell me a link or answer?

0 Steve Kipisz over 10 years ago in reply to Robinson lei

TI__Genius 15510 points

As I said earlier, the boot ROM maps NOR to 0x08000000. Look in the Initialization chapter of the TRM, section 26.1.7.2 XIP Memory.

Steve K.

0 Robinson lei over 10 years ago in reply to Steve Kipisz

Intellectual 600 points

Thank you Steve Kipisz

I check section 26.1.7.2 XIP Memory, it show that The ROM Code can boot directly from XIP devices and Device connected to CS0 mapped to address 0x08000000.

I think understand.

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GPMC config for NOR flash