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CHAPTER 4 EEPROM
4.7 Cautions regarding EEPROM Writing
The following shows cautions of EEPROM write.
Before performing EEPROM write, be sure to read the following cautions.
(1) Before writing, be sure to check that EWST (EEPROM write control register (EEWC) bit 1) is 0. If executing
another write instructions during EEPROM writing, the instruction executed last will be ignored.
(2) For write time, see Figure 4-2.
(3) If performing several write operations in succession, be sure to wait until the current write operation is completed
before starting the next one.
(4) Even if the mode changes to HALT mode during EEPROM writing, writing is continued.
(5) If the mode changes to STOP mode during EEPROM writing, the data being written becomes undefined. If this
STOP mode is cancelled by interrupt request, a write termination interrupt request (INTWE) is generated after
the STOP mode has been cancelled. If you want to set the STOP mode after normally terminating write
processing, check that write processing has ended using any of the available methods (refer to 4.5 EEPROM
Writing), then set the STOP mode.
(6) If you want to read the EEPROM contents immediately after changing EWCC (EEPROM write control register
(EEWC) bit 2) from 1 to 0, set a wait time of 20
µ
s or more by software. If no wait time is set, the data read will
not be correct.
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