ATTINY261_0611 Datasheet, PDF (68/236 Pages) ATMEL Corporation – 8-bit Microcontroller with 2/4/8K Bytes In-System Programmable Flash

12.4 Register Description
12.4.1 MCUCR – MCU Control Register
Bit
7
0x35 (0x55) -
Read/Write R
Initial Value 0
6
5
PUD
SE
R/W
R/W
0
0
4
SM1
R/W
0
3
2
SM0
-
R/W
R
0
0
1
ISC01
R
0
0
ISC00
R
0
MCUCR
• Bit 6 – PUD: Pull-up Disable
When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn and
PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01). See ”Con-
figuring the Pin” on page 54 for more details about this feature.
12.4.2
PORTA – Port A Data Register
Bit
0x1B (0x3B)
Read/Write
Initial Value
7
PORTA7
R/W
0
6
PORTA6
R/W
0
5
PORTA5
R/W
0
4
PORTA4
R/W
0
3
PORTA3
R/W
0
2
PORTA2
R/W
0
1
PORTA1
R/W
0
0
PORTA0
R/W
0
PORTA
12.4.3
DDRA – Port A Data Direction Register
Bit
0x1A (0x3A)
Read/Write
Initial Value
7
DDA7
R/W
0
6
DDA6
R/W
0
5
DDA5
R/W
0
4
DDA4
R/W
0
3
DDA3
R/W
0
2
DDA2
R/W
0
1
DDA1
R/W
0
0
DDA0
R/W
0
DDRA
12.4.4
PINA – Port A Input Pins Address
Bit
0x19 (0x39)
Read/Write
Initial Value
7
PINA7
R/W
N/A
6
PINA6
R/W
N/A
5
PINA5
R/W
N/A
4
PINA4
R/W
N/A
3
PINA3
R/W
N/A
2
PINA2
R/W
N/A
1
PINA1
R/W
N/A
0
PINA0
R/W
N/A
PINA
12.4.5
PORTB – Port B Data Register
Bit
0x18 (0x38)
Read/Write
Initial Value
7
PORTB7
R/W
0
6
PORTB6
R/W
0
5
PORTB5
R/W
0
4
PORTB4
R/W
0
3
PORTB3
R/W
0
2
PORTB2
R/W
0
1
PORTB1
R/W
0
0
PORTB0
R/W
0
PORTB
12.4.6
DDRB – Port B Data Direction Register
Bit
0x17 (0x37)
Read/Write
Initial Value
7
DDB7
R/W
0
6
DDB6
R/W
0
5
DDB5
R/W
0
4
DDB4
R/W
0
3
DDB3
R/W
0
2
DDB2
R/W
0
1
DDB1
R/W
0
0
DDB0
R/W
0
DDRB
12.4.7
PINB – Port B Input Pins Address
Bit
0x16 (0x36)
Read/Write
Initial Value
7
PINB7
R/W
N/A
6
PINB6
R/W
N/A
5
PINB5
R/W
N/A
4
PINB4
R/W
N/A
3
PINB3
R/W
N/A
2
PINB2
R/W
N/A
1
PINB1
R/W
N/A
0
PINB0
R/W
N/A
PINB
68 ATtiny261/461/861
2588B–AVR–11/06