Rainbow Electronics ATmega128RFA1 - Manual (Page 21)

21
8266A-MCU Wireless-12/09
ATmega128RFA1
The following code examples show one assembly and one C function for writing to 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.
The examples also assume that no Flash Boot Loader is present in the software. If such
code is present, the EEPROM write function must also wait for any ongoing SPM
command to finish.
Assembly Code Example
EEPROM_write:
; Wait for completion of previous write
sbic EECR,EEPE
rjmp EEPROM_write
; Set up address (r18:r17) in address register
out EEARH, r18
out EEARL, r17
; Write data (r16) to Data Register
out EEDR,r16
; 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 uiAddress, unsigned char ucData)
{
/* Wait for completion of previous write */
while(EECR & (1<
;
/* Set up address and Data Registers */
EEAR = uiAddress;
EEDR = ucData;
/* Write logical one to EEMPE */
EECR |= (1<
/* Start eeprom write by setting EEPE */
EECR |= (1<
}
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.
Assembly Code Example
EEPROM_read:
; Wait for completion of previous write