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EERPORM record system worn out with 28 dropped sectors

Question asked by Richard Tyson on Nov 23, 2015
Latest reply on Dec 2, 2015 by Richard Tyson

Hello All,

I have been confused by a trouble with the EEPROM of MC9S12XET256 for quite a long time.I'm trying to find out the reason causes the EEEPROM worn out.

At first,I'm sure the XET256 was partitioned with ERPART=16  and DFPART=0 (all of the 4K D-Flash are used for EEEPROM).Then a few days later,The EEEPROM could't restore data any longer.When read the value in address such as 0x10_0000,0x10_0100....0x10_7F00(the head of date record sector),there are about 28 sector heads with the value of 0xFFFF.According to the AN3490 4.4 Record System Status "The number of dropped EEE NVM sectors that can be managed by the EEE is limited to a maximum of 24". I think this maybe the reason the EEPROM didn't work.Meanwhile,the ERPART and DFPART also turned to 0xFFFF,but could not read the value in 0x12_0000,0x12_0004(both are 0x0, with EEEIFRON = 1).Howerer,when I repartiton the EEPROM  with the Full Partition D-Flash command (0x0F) by BDM,the EEPROM recover again.I have tried to turn off the power off while reading and writing the EEPROM,which may corrupt  the record system,but it didn't work.

My question is:

1)what's the reason cause the EEPROM "Pseudo worn out"?

2)Are there any methods to reappear the fault,and how?