Hello,
We have problems with one of our customers, who have issues with the programming of the 128-bit key used in the HMAC calculation. He says that he can reprogram the KEY0 and KEY1 repeatedly. This should be not possible according to our implementation, because after each programming of KEYx we perform the programming of the appropriate LOCKKx bit. This LOCKKx bits are tested before each programming of KEYx and if they are set ('0' state) we don't allow any further programming action. We verified the LOCKKx programming sequence with the documentation and find a discrepancy. Our implementation was made according the documentation from 06/2006 and 02/2007, where it says "Address 0x0000 PAGE LOCK". But in the latest 02/2019 documentation is it written that the "PAGE LOCK (offset = D431h) [reset = 0h]".
Q1.: Is it means that the PAGE LOCK address 0x0000 is incorrect, and the correct address is 0xD431h?
Q2.: If Q1 answer is YES, is the revised address valid for all devices from first samples from year 2006?
Q3.: "PAGE LOCK (offset = D431h) [reset = 0h]" what means "[reset = 0h]"? This is the value of PAGE LOCK after reset? If yes than the LOCKKx are set to 0, and the KEYx are locked after reset? How to unlock them? Is the reset value correct?
Best regard,
Frantisek
