75
7734Q–AVR–02/12
AT90PWM81/161
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
“Con-9.3.2
Alternate Functions of Port B
The Port B pins with alternate functions are shown in
Table 9-3.
The alternate pin configuration is as follows:
PSCOUT22/ICP1/ADC9 – Bit 7
PSCOUT22: Output 2 of PSC 2
ICP1 – Input Capture Pin1: This pin can act as an input capture pin for Timer/Counter1.
ADC9: Analog to Digital Converter, input channel 9.
MISO/ACMP3/ADC8– Bit 6
MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is enabled as a
master, this pin is configured as an input regardless of the setting of DDB6. When the SPI is
enabled as a slave, the data direction of this pin is controlled by DDB6. When the pin is forced to
be an input, the pull-up can still be controlled by the PORTB6 and PUD bits.
ACMP3: Analog Comparator 3 Positive Input. Configure the port pin as input with the internal
pull-up switched off to avoid the digital port function from interfering with the function of the Ana-
log Comparator.
ADC8: Analog to Digital Converter, input channel 8.
Table 9-3.
Port B pins alternate functions.
Port pin
Alternate functions
PB7
PSCOUT22 output
ICP1 (Timer/Counter1 Input Capture Pin )
ADC9 (Analog Input Channel 9)
PB6
MISO (SPI Master In Slave Out)
ACMP3 (Analog Comparator 3 Positive Input )
ADC8 (Analog Input Channel 8)
PB5
ADC5 (Analog Input Channel 5)
ACMP2 (Analog Comparator 2 Positive Input)
INT1(External Interrupt 1 Input)
SCK (SPI Clock)
PB4
MOSI (SPI Master Out Slave In)
ADC3 (Analog Input Channel 3)
ACMPM reference for analog comparators
PB3
PSCOUTR1 Output
ADC2 (Analog Input Channel 2)
ACMP2M (Analog Comparator 2 Negative Input)
PB2
INT0 (External Interrupt 0 Input)
PSCOUT21 output
PB1
PSCOUT20 output
PB0
T1 counter source
PSCOUT23 output
ACMP3_OUT( Analog Comparator3 Output)