ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 59

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

MCU Control Register –
MCUCR
Alternate Functions of Port B
2570A–AVR–09/04
• 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 53 for more details about this feature.
The Port B pins with alternate functions are shown in Table 26.
Table 26. Port B Pins Alternate Functions
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
Read/Write
Initial Value
Port Pin
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
JTD
R/W
7
0
Alternate Functions
OC2A/PCINT15 (Output Compare and PWM Output A for Timer/Counter2 or
Pin Change Interrupt15).
OC1B/PCINT14 (Output Compare and PWM Output B for Timer/Counter1 or
Pin Change Interrupt14).
OC1A/PCINT13 (Output Compare and PWM Output A for Timer/Counter1 or
Pin Change Interrupt13).
OC0A/PCINT12 (Output Compare and PWM Output A for Timer/Counter0 or
Pin Change Interrupt12).
MISO/PCINT11 (SPI Bus Master Input/Slave Output or Pin Change
Interrupt11).
MOSI/PCINT10 (SPI Bus Master Output/Slave Input or Pin Change
Interrupt10).
SCK/PCINT9 (SPI Bus Serial Clock or Pin Change Interrupt9).
SS/PCINT8 (SPI Slave Select input or Pin Change Interrupt8).
R
6
–
0
R
5
–
0
ATmega325/3250/645/6450
PUD
R/W
4
0
R
3
–
0
R
2
–
0
IVSEL
R/W
1
0
IVCE
R/W
0
0
MCUCR
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