13.12.3 Memory Selection

The CRC-on-boot module can be configured to scan and perform a CRC on five NVM regions: The boot, application, SAF segments of program memory, data EEPROM memory and Configuration Words. Each is enabled individually by clearing Configuration bits CFGSCEN, DATSCEN, SAFSCEN, APPSCEN and BOOTSCEN for the configuration memory, EEPROM, SAF section, application section and boot section, respectively. Each memory segment is treated slightly differently and can vary based on other configuration settings:

• The data EEPROM segment scans the entire data EEPROM memory of the device
• The configuration memory scans all configuration memory, except the four bytes for the non-boot CRC expected value (as this would be self-referencing and cause issues in CRC calculation)
• The SAF area scans the Storage Area Flash region (the last 128 words of program memory) if the SAFEN Configuration bit is cleared (Storage Area Flash enabled). If the Storage Area Flash is disabled, attempting to scan this region will result in the CRC-on-boot indicating a mismatch.
• The boot area scans the region of program memory defined by the BBEN and BBSIZE Configuration bits. If the BBEN bit is set (disabling boot area), attempting to scan this region will result in the CRC-on-boot indicating a mismatch.
• The application area scans the remainder of program memory not specifically designated for the Boot Block or the SAF