Rainbow-electronics ATmega64L Manual de usuario descargar pdf (Pagina 18)

ATmega16(L)

2466B–09/01

EEWE has been set, the CPU is halted for two cycles before the next instruction is

executed.

• Bit 0 - EERE: EEPROM Read Enable

The EEPROM Read Enable Signal EERE is the read strobe to the EEPROM. When the

correct address is set up in the EEAR register, the EERE bit must be written to a logic

one to trigger the EEPROM read. The EEPROM read access takes one instruction, and

the requested data is available immediately. When the EEPROM is read, the CPU is

halted for four 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

The calibrated oscillator is used to time the EEPROM accesses. Table 1 lists the typical

programming time for EEPROM access from the CPU.

Table 1. EEPROM Programming Time.

Symbol

Number of

Calibrated RC-

oscillator Cycles

Min

Programming

Time

Max

Programming

Time

EEPROM write (from CPU) approximately 8300 7.5 ms 9.0 ms

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 297 298

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Rainbow-electronics ATmega64L Manual de usuario Pagina 18