Datasheet

66
ATmega325/3250/645/6450
2570K–AVR–04/07
MCUCR – MCU Control
Register
• Bit 4 – 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 59 for more details about this feature.
Alternate Functions of Port B The Port B pins with alternate functions are shown in Table 27.
The alternate pin configuration is as follows:
• OC2A/PCINT15, Bit 7
OC2, Output Compare Match A output: The PB7 pin can serve as an external output for
the Timer/Counter2 Output Compare A. The pin has to be configured as an output
(DDB7 set (one)) to serve this function. The OC2A pin is also the output pin for the PWM
mode timer function.
PCINT15, Pin Change Interrupt source 15: The PB7 pin can serve as an external inter-
rupt source.
• OC1B/PCINT14, Bit 6
OC1B, Output Compare Match B output: The PB6 pin can serve as an external output
for the Timer/Counter1 Output Compare B. The pin has to be configured as an output
(DDB6 set (one)) to serve this function. The OC1B pin is also the output pin for the PWM
mode timer function.
PCINT14, Pin Change Interrupt Source 14: The PB6 pin can serve as an external inter-
rupt source.
Bit 7 6 5 4 3 2 1 0
0x35 (0x55)
JTD – –PUD– – IVSEL IVCE MCUCR
Read/Write R/W R R R/W R R R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Table 27. Port B Pins Alternate Functions
Port Pin Alternate Functions
PB7
OC2A/PCINT15
(Output Compare and PWM Output A for Timer/Counter2 or
Pin Change Interrupt15).
PB6
OC1B/PCINT
14 (Output Compare and PWM Output B for Timer/Counter1 or
Pin Change Interrupt14).
PB5
OC1A/PCINT13
(Output Compare and PWM Output A for Timer/Counter1 or
Pin Change Interrupt13).
PB4
OC0A/PCINT12
(Output Compare and PWM Output A for Timer/Counter0 or
Pin Change Interrupt12).
PB3
MISO/PCINT11
(SPI Bus Master Input/Slave Output or Pin Change
Interrupt11).
PB2
MOSI/PCINT10
(SPI Bus Master Output/Slave Input or Pin Change
Interrupt10).
PB1 SCK/PCINT9
(SPI Bus Serial Clock or Pin Change Interrupt9).
PB0 SS/PCINT8
(SPI Slave Select input or Pin Change Interrupt8).