PXD10RM Datasheet, PDF (634/1332 Pages) Freescale Semiconductor, Inc – PXD10 Microcontroller

This option allows to perform a Blank Check after a Sector Erase operation.
17.3.8.2 Bit manipulation
The ECC algorithm allows some bit manipulations so that a Double Word can be rewritten several times
without needing an erase of the sector. This allows to use a Double Word to store flags useful for the
Eeprom Emulation.
As an example the ECC algorithm allows to start from an All ‘1’s Double Word value and rewrite
whichever of its four 16-bits Half-Words to an All ‘0’s content by keeping the same ECC value.
Table 17-60 shows a set of Double Words sharing the same ECC value.
Table 17-60. Bit manipulation: Double Words with the same ECC value
Double Word
0xFFFF_FFFF_FFFF_FFFF
0xFFFF_FFFF_FFFF_0000
0xFFFF_FFFF_0000_FFFF
0xFFFF_0000_FFFF_FFFF
0x0000_FFFF_FFFF_FFFF
0xFFFF_FFFF_0000_0000
0xFFFF_0000_FFFF_0000
0x0000_FFFF_FFFF_0000
0xFFFF_0000_0000_FFFF
0x0000_FFFF_0000_FFFF
0x0000_0000_FFFF_FFFF
0xFFFF_0000_0000_0000
0x0000_FFFF_0000_0000
0x0000_0000_0000_0000
ECC
0xFF
17.3.8.3 EEPROM emulation
When some Flash sectors are used to perform an EEPROM emulation, it is reccomended for safety reasons
to reserve at least 3 sectors to this purpose.
17.3.9 Protection Strategy
Two kind of protections are available: Modify Protection to avoid unwanted program/erase in Flash sectors
and Censored Mode to avoid piracy.
17-84
PXD10 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor