Rainbow Electronics ATtiny43U - Manual (Page 18)

18
8048B–AVR–03/09
ATtiny43U
data that is stored must be considered as lost. While the device is busy with programming, it is
not possible to do any other EEPROM operations.
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 28 .
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<
out EECR, r16
; Set up address (r17) in address register
out EEAR, 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 char ucAddress, unsigned char ucData)
{
/* Wait for completion of previous write */
while(EECR & (1<
;
/* Set Programming mode */
EECR = (0<
/* Set up address and data registers */
EEAR = ucAddress;
EEDR = ucData;
/* Write logical one to EEMPE */
EECR |= (1<
/* Start eeprom write by setting EEPE */
EECR |= (1<
}