36.5.3.7.4 Locking a Packet

To lock a packet, follow the steps below:

  1. Write the address value of the header of the packet to lock in OTPC_MR.ADDR.
  2. Start a read by setting OTPC_CR.READ and waiting for the read completion indicated by OTPC_ISR.EOR.
  3. Write 0x7167 in the OTPC_CR.KEY field and ‘1‘ in OTPC_CR.CKSGEN.

The end of the lock operation is indicated by OTPC_ISR.EOL=’1’ and/or OTPC_SR.LOCK=’0’.

Generating the checksum locks the packet and modification is no longer possible.