TMS320F28377S: Zone Select Block function in DCSM

Brian Wang0

Part Number: TMS320F28377S

Hi,

I am working with DCSM on F28337s.

I noticed multiple zone select blocks are provided on f28377s. At first, I believe it is designed to give users multiple chances to set their passwords.

However, as I learn deeper, I noticed the LINKPOINTER registers which decide the location of zone select block also locate in OTP, which means users cannot change the location of their password once they decide.

Is my understanding right? If my understanding is right, why we have multiple zone select blocks? For security purpose, to make it difficult to locate the password?

Thanks!

over 7 years ago

0 Brian Wang0 over 7 years ago

TI__Expert 5370 points

Besides, I cannot find the description of Zx-GRABRAMx register in the .
Only Zx-GRABRAMRx (READ ONLY statues bit) explanation is found.
I just want to know are the bits in these two registers the same correspondingly?

0 EK over 7 years ago

Expert 2520 points

Hi Weiki,

Linkpointer is not ECC protected, instead it consists of 3 locations (LINKPOINTER1, -2, -3), which should be the same. If they are not the same, voting scheme is applied. This makes LINKPOINTER not at all one time programmable, you can program more zero bits to linkpointer. You start with blank 0xFFFFFFFF linkpointer, which selects zone 0, then write 0xFFFFFFFE to linkpointer, which selects zone 1, 0xFFFFFFFC - 2 and so on.

Different zones may have not only different passwords, but also different security settings (GRABRAM, GRABSECT, EXEONLYRAM, EXEONLYSECT).

Edward

0 EK over 7 years ago in reply to EK

Expert 2520 points

Yes, Zx-GRABRAM register matches with OTP GRABRAM settings.

Edward

0 Vivek Singh over 7 years ago in reply to EK

TI__Guru** 115671 points

Thanks Edward. You have correctly explained it.

Brian,

Let me know if you have any further queries.

Regards,

Vivek Singh

0 Brian Wang0 over 7 years ago in reply to EK

TI__Expert 5370 points

Thank you so much and I have on more question:
In f280049, I write 0x1FFFFFFE to B0_Z1_linkpointer successfully(Can be viewed in memory browser)
According to the manual, I believe, the value of B1_Z1_LINKPOINTER_1 in DcsmBank1Z1Regs should also be 0x1FFFFFFE. However the value is 0xFFFFFFFE. Why?

0 EK over 7 years ago in reply to Brian Wang0

Expert 2520 points

Hi,

Try looking again at Z1_LINKPOINTER register description. It is told that bits 31-29 are always all ones (R-7h)

Edward

0 Vivek Singh over 7 years ago in reply to EK

TI__Guru** 115671 points

Hi Weiki,
I hope this issue is resolved?

Vivek Singh

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TMS320F28377S: Zone Select Block function in DCSM