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CHAPTER 4 EEPROM
4.4 EEPROM Reading
Reading of EEPROM data is performed with the following procedure.
<1> Check that EWST (EEPROM write control register (EEWC) bit 1) is 0 (EEPROM writing is not in
progress).
<2> Execute read instruction.
Cautions 1. Before reading, be sure to check that EWST is 0. If an EEPROM read instruction is executed
during EEPROM write, read values are undefined.
2. If reading EEPROM contents immediately after changing EWCC (EEPROM write control
register (EEWC) bit 2) from 1 to 0, set a wait time of at least 20
µ
s by software.
If no wait time is set, the correct values cannot be read.
Example: Insertion of NOP instructions to set wait time of 20
µ
s or more.
CLR1 EWCC
NOP
Insert NOP instructions to secure a wait time of 20
µ
s or more.
NOP
MOV A,!0F800H
Содержание mPD780973 Series
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