CHAPTER 5 EEPROM (DATA MEMORY)User’s Manual U14826EJ5V0UD 615.4 Notes for EEPROM WritingThe following caution points pertain to writing to EEPROM.(1) When fetching an instruction from EEPROM or stopping the system clock oscillator, be sure to do so aftersetting EEPROM to write-disabled (EWE10 = 0).(2) Set the count clock in a state in which the selected clock is operating (oscillating). If the selected count clockis stopped, there is no transition to the state in which writing is possible even if the clock operation issubsequently started and EEPROM is set to write-enabled (EWE10 = 1).(3) Be sure to set the EEPROM write time within the range of 3.3 to 6.6 ms.(4) When setting ERE10 and EWE10, be sure to use the following procedure. If you set these using other thanthe following procedure, there is no transition to the state in which writing to EEPROM is possible.<1> Set ERE10 to 1 (In a state in which EWE10 = 0)<2> Set EWE10 to 1 (In a state in which ERE10 = 1)<3> Wait 1 ms or more using software<4> Shift to state in which writing to EEPROM is possibleERE10AB CEWE10D1 ms or moreA (ERE10 = 1): Transition to state in which reading is possibleB (EWE10 = 1): Set count clock before this point.C: Transition to state in which writing is possibleD: When ERE10 is cleared (ERE10 = 0), EWE10 is also cleared (EWE10 = 0).Reading or writing is not possible in this state.(5) When performing a write to EEPROM, execute it after confirming that EWST10 = 0.If a write is executed to EEPROM when EWST10 = 1, the instruction is ignored.
