ATmega328P datasheet(25/448 Pages) ATMEL

25 / 448 page

8161D–AVR–10/09

ATmega48PA/88PA/168PA/328P

The next code examples show assembly and C functions for reading the EEPROM. The exam-

ples assume that interrupts are controlled so that no interrupts will occur during execution 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,EEPE

rjmp

EEPROM_read

; Set up address (r18:r17) in address register

out

EEARH, r18

out

EEARL, r17

; Start eeprom read by writing EERE

sbi

EECR,EERE

; Read data from Data Register

r16,EEDR

ret

C Code Example

unsigned char

EEPROM_read(unsigned int uiAddress)

{

/* Wait for completion of previous write */

while(EECR & (1<<EEPE))

;

/* Set up address register */

EEAR = uiAddress;

/* Start eeprom read by writing EERE */

EECR |= (1<<EERE);

/* Return data from Data Register */

return EEDR;

}

Bit

654

0x2B (0x4B)

MSB

LSB

GPIOR2

Read/Write

R/W

Initial Value

Bit

654

0x2A (0x4A)

MSB

LSB

GPIOR1

Read/Write

R/W

Initial Value

Bit

654

0x1E (0x3E)

MSB

LSB

GPIOR0

Read/Write

R/W

Initial Value

ATmega328P Datasheet(PDF) 25 Page - ATMEL Corporation

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