ATmega325P datasheet(27/364 Pages) ATMEL

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8023F–AVR–07/09

ATmega325P/3250P

7.6.4

General Purpose I/O Registers

The ATmega325P/3250P contains three General Purpose I/O Registers. These registers can be

used for storing any information, and they are particularly useful for storing global variables and

Status Flags. General Purpose I/O Registers within the address range 0x00 - 0x1F are directly

bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.

7.6.5

GPIOR2 – General Purpose I/O Register 2

7.6.6

GPIOR1 – General Purpose I/O Register 1

Assembly Code Example

EEPROM_read:

; Wait for completion of previous write

sbic

EECR,EEWE

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<<EEWE))

;

/* Set up address register */

EEAR = uiAddress;

/* Start eeprom read by writing EERE */

EECR |= (1<<EERE);

/* Return data from Data Register */

return EEDR;

}

Bit

543210

0x2B (0x4B)

MSB

LSB

GPIOR2

Read/Write

R/W

Initial Value

000000

Bit

543210

0x2A (0x4A)

MSB

LSB

GPIOR1

Read/Write

R/W

Initial Value

000000

ATmega325P データシート(PDF) 27 Page - ATMEL Corporation

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