SPRUJF8 May 2026 TMS320F28P551SG
For each of the two security zones, a dedicated OTP block exists that holds the configuration related to zone’s security. Each zone's OTP block is further organized into a single zone header and up to 15 Zone-Select Blocks (ZSB). The zone header contains DCSM configurations that can only be configured once since OTP cannot be erased. However, the active ZSBs can be changed by decrementing the Link Pointer, allowing for new ZSB configurations to be selected by the user.
Figure 5-1 shows the user-programmable configurations of each zone’s OTP:
The location of the valid Zone-Select Block in OTP is decided based on the value of three 14-bit link pointers (ZxOTP_LINKPOINTER1) programmed in the OTP of each zone. All OTP locations except link pointers and Z1OTP_JLM_ENABLE locations are protected with ECC. Since the link pointer locations are not protected with ECC, three link pointers are provided that need to be programmed with the same value. 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). Since in OTP, a 1 can be flipped by the user to 0, but 0 can not be flipped to 1 (no erase operation for OTP), the most-significant bit position in the resolved link pointer that is 0 defines the valid base address for the zone select block.
While generating the final link pointer value, if the bit pattern is not one of those listed in Figure 5-2, the final link pointer value becomes All_1 (0xFFFF_FFFF), selecting ZSB1 (also known as the default zone select block).
Figure 5-2 Storage of Zone-Select Bits in
OTP