Datasheet

24
8018P–AVR–08/10
ATmega169P
When the write access time has elapsed, the EEWE bit is cleared by hardware. The user soft-
ware can poll this bit and wait for a zero before writing the next byte. When EEWE has been set,
the CPU is halted for two cycles before the next instruction is executed.
The user should poll the EEWE bit before starting the read operation. If a write operation is in
progress, it is neither possible to read the EEPROM, nor to change the EEAR Register.
The calibrated Oscillator is used to time the EEPROM accesses. Table 7-1 lists the typical pro-
gramming time for EEPROM access from the CPU.
Table 7-1. EEPROM Programming Time
Symbol
Number of Calibrated
RC Oscillator Cycles Typical Programming Time
EEPROM write (from CPU) 27 072 3.3 ms