NXP Semiconductors MWCT101 S Series, Reference Manual

Page: 740 / 1761

Data flash memory is useful for applications that need to quickly store large amounts of
data or store data that is static. The emulated EEPROM partition in FlexRAM is useful
for storing smaller amounts of data that will be changed often.
32.5.2.3 EEPROM implementation overview
Out of reset with the FSTAT[CCIF] bit clear, the partition settings (EEESIZE, DEPART)
are read from the data flash IFR and the emulated EEPROM file system is initialized
accordingly. The emulated EEPROM file system locates all valid EEPROM data records
in EEPROM backup and copies the newest data to FlexRAM. The FSTAT[CCIF] and
FCNFG[EEERDY] bits are set after data from all valid EEPROM data records is copied
to the FlexRAM. After the CCIF bit is set, the FlexRAM is available for read or write
access.
When configured for emulated EEPROM use, writes to an unprotected location in
FlexRAM invokes the emulated EEPROM file system to program a new EEPROM data
record in the emulated EEPROM backup memory in a round-robin fashion. As needed,
the emulated EEPROM file system identifies the emulated EEPROM backup sector that
is being erased for future use and partially erases that emulated EEPROM backup sector.
After a write to the FlexRAM, the FlexRAM is not accessible until the FSTAT[CCIF] bit
is set. The FCNFG[EEERDY] bit will also be set. If enabled, the interrupt associated
with the FSTAT[CCIF] bit can be used to determine when the FlexRAM is available for
read or write access.
After a sector in emulated EEPROM backup is full of EEPROM data records, EEPROM
data records from the sector holding the oldest data are gradually copied over to a
previously-erased emulated EEPROM backup sector. When the sector copy completes,
the emulated EEPROM backup sector holding the oldest data is tagged for erase.
CAUTION
Interrupting an emulated EEPROM operation (due to power
loss, reset, supplies out of specified operational ranges, or any
other reasons) will leave the contents in an indeterminate state.
The user must take appropriate counter measures to prevent
data loss in case of an interrupted emulated EEPROM
operation.
32.5.2.4 Write endurance to FlexRAM for emulated EEPROM
When the FlexNVM partition code is not set to full data flash, the emulated EEPROM
data set size should be set to the non-zero value.
Functional description
MWCT101xS Series Reference Manual, Rev. 3, 07/2019
740 NXP Semiconductors