36.5.3.8 Fixing Corruption

During a programming sequence, packet header corruption may occur. This corruption can be caused by a partial programming of the header. It is mandatory to fix any corruption prior to any usage of the Engineering Area or User Area.

During the start sequence, the OTPC stops parsing the OTP memory at the first header corruption detected. When OTPC_ISR.COERR is set, a corruption has been detected. The corrupted header can be read in OTPC_HR and its location can be read in OTPC_MR.ADDR.

A header is corrupted if at least one of the following statements matches:
  • The ONE bit is cleared (it must be set to fix the corruption).
  • The INVLD field is 3 and the PACKET field is 0 (PACKET must be set to a non-0 value to fix the corruption).
  • The SIZE and PACKET fields are not consistent (for PACKET set to PRODUCT_UID, HARDWARE_CONFIGURATION or SECURITY_CONFIGURATION, the packet must be invalidated to fix the corruption).

To fix a corruption, start a a read procedure at the location of the corrupted header. The OTPC reads the payload according to the size provided in the header and reads one extra word of payload, which should match the next header.

The corrupted header must be fixed by writing any missing ‘1’s or, if not possible, by extending its size if the supposed next header is 0, or by invalidating the packet.

A reset is required after fixing the corruption.