attiny13-20ss ATMEL Corporation, attiny13-20ss Datasheet - Page 51

• Manufacturer Part Number: attiny13-20ss
• Description: 8-bit Microcontroller With 1k Bytes In-system Programmable Flash - Atmel Corporation
• Manufacturer: ATMEL Corporation

MCU Control Register –
MCUCR
Alternate Functions of Port B
2535G–AVR–01/07
• 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 44 for more details about this feature.
The Port B pins with alternate function are shown in Table 21.
Table 21. Port B Pins Alternate Functions
Notes:
Table 22 and Table 23 on page 52 relate the alternate functions of Port B to the overrid-
ing signals shown in Figure 24 on page 49.
Bit
Read/Write
Initial Value
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
5. Serial Data Input, Analog Comparator Negative Input, Output Compare and PWM
6. Serial Data Output, Analog Comparator Positive Input, Output Compare and PWM
Port Pin
PB5
PB4
PB3
PB2
PB1
PB0
Interrupt.
Output B for Timer/Counter, External Interrupt 0 or Pin Change Interrupt.
Output A for Timer/Counter, or Pin Change Interrupt.
R
7
–
0
PUD
R/W
6
0
RESET/dW/ADC0/PCINT5
ADC2/PCINT4
ADC3/CLKI/PCINT3
SCK/ADC1/T0/PCINT2
MISO/AIN1/OC0B/INT0/PCINT1/RXD
Alternate Function
MOSI/AIN0/OC0A/PCINT0/TXD
R/W
SE
5
0
(2)
SM1
R/W
4
0
(3)
(4)
SM0
R/W
3
0
(1)
(6)
R
2
–
0
(5)
ISC01
R/W
1
0
ISC00
R/W
0
0
MCUCR
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