Rainbow Electronics ATmega64M1 - Manual (Page 26)

26
8209A–AVR–08/09
ATmega16M1/32M1/64M1
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.
8.7.4 GPIOR0 – General Purpose I/O Register 0
8.7.5 GPIOR1 – General Purpose I/O Register 1
8.7.6 GPIOR2 – General Purpose I/O Register 2
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
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 */
EEAR = uiAddress;
/* Start eeprom read by writing EERE */
EECR |= (1<<EERE);
/* Return data from data register */
return EEDR;
}
Bit 7 6 5 4 3 2 1 0
GPIOR07 GPIOR06 GPIOR05 GPIOR04 GPIOR03 GPIOR02 GPIOR01 GPIOR00 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
Bit 7 6 5 4 3 2 1 0
GPIOR17 GPIOR16 GPIOR15 GPIOR14 GPIOR13 GPIOR12 GPIOR11 GPIOR10 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 7 6 5 4 3 2 1 0
GPIOR27 GPIOR26 GPIOR25 GPIOR24 GPIOR23 GPIOR22 GPIOR21 GPIOR20 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