Datasheet

50
ATtiny13
2535E–AVR–10/04
MCU Control Register –
MCUCR
• Bits 7, 2– Res: Reserved Bits
These bits are reserved bits in the ATtiny13 and will always read as zero.
• 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 “Configuring the Pin” on page 43 for more details about this feature.
Alternate Functions of Port B The Port B pins with alternate function are shown in Table 21.
Notes: 1. Reset pin, debugWire I/O, ADC Input channel, or Pin Change Interrupt.
2. ADC Input channel or Pin Change Interrupt.
3. ADC Input channel, Clock Input, or Pin Change Interrupt.
4. Serial Clock Input, Timer/Counter Clock Input, ADC Input Channel 0, or Pin Change
Interrupt.
5. Serial Data Input, Analog Comparator Negative Input, Output Compare and PWM
Output B for Timer/Counter, External Interrupt 0 or Pin Change Interrupt.
6. Serial Data Output, Analog Comparator Positive Input, Output Compare and PWM
Output A for Timer/Counter, or Pin Change Interrupt.
Table 22 and Table 23 on page 51 relate the alternate functions of Port B to the overrid-
ing signals shown in Figure 24 on page 48.
Bit 7 6 5 4 3 2 1 0
–PUD
SE SM1 SM0 – ISC01 ISC00 MCUCR
Read/Write R R/W R/W R/W R/W R R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Table 21. Port B Pins Alternate Functions
Port Pin Alternate Function
PB5 RESET
/dW/ADC0/PCINT5
(1)
PB4 ADC2/PCINT4
(2)
PB3 ADC3/CLKI/PCINT3
(3)
PB2 SCK/ADC1/T0/PCINT2
(4)
PB1 MISO/AIN1/OC0B/INT0/PCINT1/RXD
(5)
PB0 MOSI/AIN0/OC0A/PCINT0/TXD
(6)