TMS320F28379D: code security module

Hi Zou,

I figured out that the passwords of F2837x/F2807x devices are located in OTP other than flash like our older parts.

Yes, that is correct. This was done to avoid accidental locking the device while programming/erasing the main flash array.

After writing a password to lock the device, we can never bring it back to unlocked state.

I did not understand this question. Security settings are stored in Zone Select Block based on the LINK POINTER value. User can change the settings by changing the LINK POINTER VALUE to point to new Zone Select Block (please refer section "2.13.1.5 Link Pointer and Zone Select" of device document). So if you want to remove the security from device then change the LINK POINTER VALUE to next Zone Select Block and leave new Zone Select Block un-programmed (ALL_1). That will keep the device unsecure/unlock.

2. what's the point to have dual code security module?

Dual Zone security enables 3rd party development in secure environment without sharing the passwords. E.g. team A and team B can have their own secure zones to secure their IP/code on device but still allow each other to use the functions.

Regards,

Vivek Singh

Vivek,

thanks for your answer.

I want to make it clear.

For each zone, say zone1, we have Z1OTP_LINKPOINTER1, Z1OTP_LINKPOINTER2, Z1OTP_LINKPOINTER3 registers in OTP(which is one time programmable), and we also have Z1_LINKPOINTER in flash.

Z1_LINKPOINTER can not be written but only readable, it's a result by comparing Z1OTP_LINKPOINTER1, Z1OTP_LINKPOINTER2 and Z1OTP_LINKPOINTER3 in hardware, and it determines which ZoneSelectBlock we choose, right?

In TRM it's said that

The final value of the link pointer is resolved in hardware when a dummy read is done to all the link pointers by comparing all the three values (bit-wise voting logic).

Bit-wise voting logic is for example,

if bitn in Z1OTP_LINKPOINTER1, Z1OTP_LINKPOINTER2 and Z1OTP_LINKPOINTER3 is two 0s and one 1, the final bitn of Z1_LINKPOINTER is 0,

if bitn in Z1OTP_LINKPOINTER1, Z1OTP_LINKPOINTER2 and Z1OTP_LINKPOINTER3 is two 1s and one 0, the final bitn of Z1_LINKPOINTER is 1, right?

When will the dummy read of Z1OTP_LINKPOINTER1, Z1OTP_LINKPOINTER2 and Z1OTP_LINKPOINTER3 be done? Do I have to write the code to read these registers in my program?

Howard