Atmel ATtiny85 User Manual

54
7598H–AVR–07/09
ATtiny25/45/85
10.3.1 MCU Control Register – 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 48 for more details about this feature.
10.3.2 Alternate Functions of Port B
The Port B pins with alternate function are shown in Table 10-3.
Notes: 1. Reset Pin, debugWIRE I/O, ADC Input Channel or Pin Change Interrupt.
2. XOSC Output, Divided System Clock Output, ADC Input Channel, Timer/Counter1 Output
Compare and PWM Output B, or Pin Change Interrupt.
3. XOSC Input / External Clock Input, ADC Input Channel, Timer/Counter1 Inverted Output Com-
pare and PWM Output B, or Pin Change Interrupt.
4. Serial Clock Input, ADC Input Channel, Timer/Counter Clock Input, USI Clock (three-wire
mode), USI Clock (two-wire mode), External Interrupt, or Pin Change Interrupt.
5. Serial Data Input, Analog Comparator Negative Input, Timer/Counter0 Output Compare and
PWM Output B, Timer/Counter1 Output Compare and PWM Output A, USI Data Output
(three-wire mode), or Pin Change Interrupt.
6. Serial Data Output, Analog Comparator Positive Input, Timer/Counter0 Output Compare and
PWM Output A, Timer/Counter1 Inverted Output Compare and PWM Output A, USI Data Input
(three-wire mode), USI Data (two-wire mode), Voltage Ref., or Pin Change Interrupt.
• Port B, Bit 5 - RESET/dW/ADC0/PCINT5
RESET
: External Reset input is active low and enabled by unprogramming (“1”) the RSTDISBL
Fuse. Pullup is activated and output driver and digital input are deactivated when the pin is used
as the RESET
pin.
dW: When the debugWIRE Enable (DWEN) Fuse is programmed and Lock bits are unpro-
grammed, the debugWIRE system within the target device is activated. The RESET
port pin is
configured as a wire-AND (open-drain) bi-directional I/O pin with pull-up enabled and becomes
the communication gateway between target and emulator.
ADC0: Analog to Digital Converter, Channel 0
.
PCINT5: Pin Change Interrupt source 5.
Bit 7 6 5 4 3 2 1 0
BODS PUD SE SM1 SM0 BODSE ISC01 ISC00 MCUCR
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
Table 10-3. Port B Pins Alternate Functions
Port Pin Alternate Function
PB5 RESET
/ dW / ADC0 / PCINT5
(1)
PB4 XTAL2 / CLKO / ADC2 / OC1B / PCINT4
(2)
PB3 XTAL1 / ADC3 / OC1B / PCINT3
(3)
PB2 SCK / ADC1 / T0 / USCK / SCL / INT0 / PCINT2
(4)
PB1 MISO / AIN1 / OC0B / OC1A / DO / PCINT1
(5)
PB0 MOSI / AIN0 / OC0A / OC1A / DI / SDA / AREF / PCINT0
(6)

Atmel ATtiny85 Specifications

General

Brand	Atmel
Model	ATtiny85
Category	Microcontrollers
Language	English