Cannot write to GPIO DIR register on 6455

You might want to double check your GEL file. Typically the GEL file will set up a virtual memory map that CCS can use to prevent reads/writes to invalid memory (a sort of fail-safe for the user). If the GEL file does not specify this memory as valid RAM (via GEL_MapAdd() function) this could prevent CCS from allowing you to access this memory.

If this does not help please post the exact error message as this could help pin-point the problem.

You may also want to check that the GPIO is enabled in the PERCFG0 register as documented in the datasheet.  The status can be checked through the PERSTAT0 register.

Brad

Tim,

Thanks for the suggestion. The section of my gel file that pertains to the configuration registers look good...

GEL_MapAdd(0x02B00000, 0, 0x00000100, 1, 1);   /* GPIO 

Interestingly, I am not getting the access error anymore, it must have been some sort of tool issue, but when I write to the register from the memory window, it doesn't stick.

Any other ideas?

Brad,

Thanks for the help. I have one working board and one non working board. I found that even without configuring the GPIO Enable bit on the PERCFG0 on the good board I am able to read 0xFFFF FFFF (default value) from 0x02B0 0010 and write in a different value without issue, but on the 'non working' board I see 0x0000 0000 at the same address and writing a different value doesn't work. So I don't suspect this is the problem.  My gut feeling was somethign related to device configuration pins AEAxx but I have poured over these multiple times and everythign looks right.

Any other things I can try?

-aps

What's the status of GPIO in PERSTAT0 for the non-working board?  Perhaps the process for enabling it through PERCFG0 was not done properly.  You should be able to see this through PERSTAT0.