Rainbow-electronics ATmega8515L Manual de usuario descargar pdf (Pagina 20)

ATmega8515(L)

2512A–AVR–04/02

The following codeexamplesshow one assembly and one Cfunction forwriting to the

EEPROM.Theexamples assume that interrupts are controlled(e.g.,bydisabling inter-

rupts globally) sothat no interruptswill occurduring execution of these functions.The

examples alsoassume that no Flash Boot Loader ispresent in the software. If such

codeispresent, the EEPROM write function mustalso wait for any ongoing SPMcom-

mand 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

CCode 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 ATmega8515L Manual de usuario Pagina 20