Rainbow-electronics ATmega8HVD Manuel d'utilisateur télécharger pdf (Page 21)

8052B–AVR–09/08

ATmega4HVD/8HVD

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 execu-

tion of these functions.

7.6.4 GPIOR2 – General Purpose I/O Register 2

7.6.5 GPIOR1 – General Purpose I/O Register 1

7.6.6 GPIOR0 –General Purpose I/O Register 0

Assembly Code Example

EEPROM_read:

; Wait for completion of previous write

sbic EECR,EEWE

rjmp EEPROM_read

; Set up address (r17) in address register

out EEARL, r17

; Start eeprom read by writing EERE

sbi EECR,EERE

; Read data from data register

in r16,EEDR

ret

C Code Example

unsigned char EEPROM_read(unsigned int uiAddress)

{

/* Wait for completion of previous write */

while(EECR & (1<<EEWE))

;

/* Set up address register */

EEARL = uiAddress;

/* Start eeprom read by writing EERE */

EECR |= (1<<EERE);

/* Return data from data register */

return EEDR;

}

Bit 76543210

MSB LSB GPIOR2

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

Bit 76543210

MSB LSB GPIOR1

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

Bit 76543210

MSB LSB GPIOR0

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 167 168

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