Hi Todd,

I am trying the GPMC interface on AM335x for VFD (Vacuum Flouroscent 
Dsiplay) interface. I have configured the GPMC_config_registers and trying 
to Write into the configured memory address but the code crashes with 
exception. Not sure what is going wrong. I am trying this on TI starterware 
(OS less) environment using CCS. I have posted a question in TI e2e forum

 https://e2e.ti.com/support/embedded/starterware/f/790/t/490638

I am not connecting the actual VFD panel but just trying to debug this 
code. It crashes when i'm writing a byte to the configured GPMC address. 
Can you please review this and suggest me what is wrong here.

Thanks,
Seetaram



On Wednesday, 14 August 2013 09:45:15 UTC+5:30, [email protected] wrote:
>
>
> I've only used the GPMC in a non-linux, bare metal environment.  What it 
> boils down to is that in the course of setting up the GPMC, you are 
> coupling an address space in the AM335x's memory map with a particular chip 
> select, an address space in the peripheral's memory map, and timing 
> information to successfully communicate with the peripheral.  
>
> So, lets say you have mapped 0x01000000 in the AM335x's memory map to Chip 
> Select 0, and defined the space as 16MB.  If you perform a write to any 
> address between 0x01000000 and 0x01FFFFFF, the memory controller will 
> recognize this as a GPMC write, and will assert Chip select 0, and put the 
> address and data on the address and data pins, using the timing information 
> you specified.
>
> In the case of NAND memory, and other devices that cannot be directly 
> written to with a single address and data word, the GPMC can also be 
> configured to perform all of the necessary actions to allow it to write to 
> the memory.
>
> So, to answer your question, you use the GPMC by writing to or reading 
> from a memory address within the address space you've configured the GPMC 
> to control. Performs the memory access.
>

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