TMS570LC4357: How to Write to the FRAW_ADDR register in the F021 Level 2 Flash Module Controller

For test reasons, I need to have access to an internal register which maintain its value over resets.

I found the FRAW_ADDR (0xFFF8_7074) register which is cleared on a Power On Reset, but is not affected by other resets.

The documentation says that this is used during the address tag register mode (DIAGMODE=5).

It is also only writable in privileged mode.

I can access the register without a data abort, and I have tried writing a value to the register,

as well as reading a value, but the register only reads as 0x00000000.

I looked briefly for

• a protection register
• power down
• no clock
• in self-test

but so far did not find anything.

Can you read/write the FRAW_ADDR register without entering a Diagnostics mode?

If so, what does it take to write to the register?