ATMEGA64-16AI datasheet(25/393 Pages) ATMEL

25 / 393 page

ATmega64(L)

2490L–AVR–10/06

The next code examples show assembly and C functions for reading the EEPROM. The

examples assume that interrupts are controlled so that no interrupts will occur during

execution of these functions.

EEPROM Write During Power-

down Sleep Mode

When entering Power-down Sleep mode while an EEPROM write operation is active,

the EEPROM write operation will continue, and will complete before the Write Access

time has passed. However, when the write operation is completed, the oscillator contin-

ues running, and as a consequence, the device does not enter Power-down entirely. It is

therefore recommended to verify that the EEPROM write operation is completed before

entering Power-down.

Assembly Code Example

EEPROM_read:

; Wait for completion of previous write

sbic

EECR,EEWE

rjmp

EEPROM_read

; Set up address (r18:r17) in address register

out

EEARH, r18

out

EEARL, r17

; Start eeprom read by writing EERE

sbi

EECR,EERE

; Read data from data register

r16,EEDR

ret

C Code Example

unsigned char

EEPROM_read(unsigned int uiAddress)

{

/* Wait for completion of previous write */

while(EECR & (1<<EEWE))

;

/* Set up address register */

EEAR = uiAddress;

/* Start eeprom read by writing EERE */

EECR |= (1<<EERE);

/* Return data from data register */

return EEDR;

}

ATMEGA64-16AI Datasheet(PDF) 25 Page - ATMEL Corporation

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