ATTINY24 Datasheet, PDF (18/238 Pages) ATMEL Corporation – 8-bit AVR Microcontroller with 2/4/8K Bytes In-System Programmable Flash

5.3.6
The calibrated Oscillator is used to time the EEPROM accesses. Make sure the Oscillator fre-
quency is within the requirements described in “OSCCAL – Oscillator Calibration Register” on
page 30.
Program Examples
The following code examples show one assembly and one C function for erase, write, or atomic
write of the EEPROM. The examples assume that interrupts are controlled (e.g., by disabling
interrupts globally) so that no interrupts will occur during execution of these functions.
Assembly Code Example
EEPROM_write:
; Wait for completion of previous write
sbic EECR, EEPE
rjmp EEPROM_write
; Set Programming mode
ldi r16, (0<<EEPM1)|(0<<EEPM0)
out EECR, r16
; Set up address (r18:r17) in address registers
out EEARH, r18
out EEARL, r17
; Write data (r19) to data register
out EEDR, r19
; Write logical one to EEMPE
sbi EECR, EEMPE
; Start eeprom write by setting EEPE
sbi EECR, EEPE
ret
C Code Example
void EEPROM_write(unsigned int ucAddress, unsigned char ucData)
{
/* Wait for completion of previous write */
while(EECR & (1<<EEPE))
;
/* Set Programming mode */
EECR = (0<<EEPM1)|(0<<EEPM0)
/* Set up address and data registers */
EEAR = ucAddress;
EEDR = ucData;
/* Write logical one to EEMPE */
EECR |= (1<<EEMPE);
/* Start eeprom write by setting EEPE */
EECR |= (1<<EEPE);
}
Note: See “Code Examples” on page 6.
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