Device Security
288
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
System Controller (SYSCTL)
4.8.7 Device Security and Boot Overrides User Considerations
This section provides some guidelines to users for using device security and boot overrides.
1. After any of the encrypted in-field updates, user should delete the ENCPAYLOAD that was loaded into
the flash memory of the device. The boot-code does not delete this data after the in-field update is
complete. However, the boot code cleans up the decrypted data from the device before handing over
control to the user.
2. IP Protection must not be enabled for the first sector in flash main memory (address location: 0x0,
length: 4KB) if in-field updates and use of TI BSL is desired.
3. IP protection setup is allowed only in Bank 0 of main memory of flash.
4. Hardware invocation of BSL is not supported by default. Users must enable it using the boot override
mailbox.
5. The maximum size limit for ENCPAYLOAD is 16 KB less than the total SRAM size while performing
encrypted updates to IP protected secure zone or JTAG and SWD locked device. Updates larger than
this size limit must use multiple boot-override sequences.
6. If encrypted in-field updates are needed for IP protected zones:
a. SEC_ZONEx_LENGTH
≤
SYS_SRAM_SIZE - 16KB; where x = 0,1,2 or 3
b. IP protected zones with size not meeting the criteria mentioned above should be split to multiple IP
protected zones.
7. Encrypted updates to the IP protected secure zone or JTAG and SWD locked device should be done
in multiples of 4KB (flash sector size). Users should also ensure that the start address of the encrypted
update is a 4KB aligned address.
8. When Factory Reset is disabled, it cannot be enabled again.