ATmega48/88/168
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.
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
in 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;
}
7.6.4
7.6.5
7.6.6
GPIOR2 – General Purpose I/O Register 2
Bit
0x2B (0x4B)
7
6
5
4
3
2
1
0
MSB
LSB
R/W
0
GPIOR2
GPIOR1
GPIOR0
Read/Write
Initial Value
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
GPIOR1 – General Purpose I/O Register 1
Bit
7
MSB
R/W
0
6
5
4
3
2
1
0
0x2A (0x4A)
Read/Write
Initial Value
LSB
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
GPIOR0 – General Purpose I/O Register 0
Bit
7
MSB
R/W
0
6
5
4
3
2
1
0
0x1E (0x3E)
Read/Write
Initial Value
LSB
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
27
2545M–AVR–09/07
ATMEL [ ATMEL ]
