CCS/PGA970: Code locking

Hi Nigel,

The security lock prevents the digital interfaces from accessing any of the FRAM memory space. The COMBUF will still be accessible, so it is possible to program an unlock command into your firmware that will allow you to remove the security lock later for debugging.

Please see the "Accessing PGA970 Memories While the Microprocessor Is Running" section of the datasheet for more information on the COMBUF.

Regards,

Hi Scott,

That sounds like it is necessary for a "Back Door" to be added to the code which would then not be secure.

Are you saying that a XDS200 and CCS would not be able erase and reprogram the processor once the protection bits are set?

Best regards,

Nigel

Hi Scott,

I have written code to control locking and unlocking of the PGA970 but would like to test the functionality without actually locking the processor.

To do this I was hoping to write a value other than 0xAA, the lock pattern, (say 0x80) to the SECLOCK register then inspect that value to ensure I have changed it. Unfortunately I am finding that I always read back 0x00 from SECLOCK. Looking at the datasheet, page 105, it looks as if the resgister should be 8 bits of R/W. Is this an error in the datasheet or am I doing something wrong?

Best regards,

Nigel

Hi Nigel,

It should be R/W, but the read may actually not be useful. It's possible that the value isn't actually latched permanently in the register when it is written. I will check internally and get back to you.

Regards,

Hi Scott,

Have you heard back regarding latching of data in this register the read back ability? If not I will just have to cross my fingers and try it.

Best regards,

Nigel