Rainbow-electronics ATmega64L Manuale Utente Scaricare il pdf (Pagina 19)

ATmega16(L)

2466B–09/01

The following code examples show one assembly and one C function for writing to the

EEPROM. The examples assume that interrupts are controlled (for example by dis-

abling 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 soft-

ware. 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,EEWE

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 EEMWE

sbi EECR,EEMWE

; Start eeprom write by setting EEWE

sbi EECR,EEWE

ret

C Code Example

void EEPROM_write(unsigned int uiAddress, unsigned char ucData)

{

/* Wait for completion of previous write */

while(EECR & (1<<EEWE))

;

/* Set up address and data registers */

EEAR = uiAddress;

EEDR = ucData;

/* Write logical one to EEMWE */

EECR |= (1<<EEMWE);

/* Start eeprom write by setting EEWE */

EECR |= (1<<EEWE);

}

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Rainbow-electronics ATmega64L Manuale Utente Pagina 19