Datasheet

115
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
Register Description for I/O-Ports
MCUCR – MCU Control
Register
• Bit 4 – PUD: Pull-up Disable
When this bit is written to one, the I/O ports pull-up resistors are disabled even if the
DDxn and PORTxn Registers are configured to enable the pull-up resistor ({DDxn,
PORTxn} = 0b01). See “Configuring the Pin” on page 84 for more details about this
feature.
PORTA – Port A Data Register
DDRA – Port A Data Direction
Register
PINA – Port A Input Pins
Address
PORTB – Port B Data Register
DDRB – Port B Data Direction
Register
PINB – Port B Input Pins
Address
Bit 7 6 5 4 3 2 1 0
0x35 (0x55)
JTD – –PUD – – IVSEL IVCE MCUCR
Read/Write R/W RRR/W RRR/W R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
0x02 (0x22)
PORTA7 PORTA6 PORTA5 PORTA4 PORTA3 PORTA2 PORTA1 PORTA0
PORTA
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
0x01 (0x21) DDA7 DDA6 DDA5 DDA4 DDA3 DDA2 DDA1 DDA0 DDRA
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
0x00 (0x20) PINA7 PINA6 PINA5 PINA4 PINA3 PINA2 PINA1 PINA0 PINA
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value N/A N/A N/A N/A N/A N/A N/A N/A
Bit 76543210
0x05 (0x25)
PORTB7 PORTB6 PORTB5 PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 PORTB
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
0x04 (0x24) DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 DDRB
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
0x03 (0x23) PINB7 PINB6 PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 PINB
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value N/A N/A N/A N/A N/A N/A N/A N/A