ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 23

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

EEPROM Write During Power-
down Sleep Mode
2490G–AVR–03/04
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.
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 crystal oscillator
continues 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 com-
pleted before entering Power-down.
Assembly Code Example
C Code Example
EEPROM_read:
unsigned char EEPROM_read(unsigned int uiAddress)
{
}
; Wait for completion of previous write
sbic EECR,EEWE
rjmp EEPROM_read
; Set up address (r18:r17) in address register
out
out
; Start eeprom read by writing EERE
sbi
; Read data from data register
in
ret
/* 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;
;
EEARH, r18
EEARL, r17
EECR,EERE
r16,EEDR
ATmega64(L)
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