• MOSI – Port B, Bit 5
MOSI: SPI Master Data output, Slave Data input for SPI. When the SPI is enabled as a
Slave, this pin is configured as an input regardless of the setting of DDB5. When the SPI
is enabled as a Master, the data direction of this pin is controlled by DDB5. When the pin
is forced by the SPI to be an input, the pull-up can still be controlled by the PORTB5 bit.
• SS – Port B, Bit 4
SS: Slave Select input. When the SPI is enabled as a Slave, this pin is configured as an
input regardless of the setting of DDB4. As a Slave, the SPI is activated when this pin is
driven low. When the SPI is enabled as a Master, the data direction of this pin is con-
trolled by DDB4. When the pin is forced by the SPI to be an input, the pull-up can still be
controlled by the PORTB4 bit.
• AIN1/OC0 – Port B, Bit 3
AIN1, Analog Comparator Negative Input. Configure the port pin as input with the inter-
nal pull-up switched off to avoid the digital port function from interfering with the function
of the analog comparator.
OC0, Output Compare Match output: The PB3 pin can serve as an external output for
the Timer/Counter0 Compare Match. The PB3 pin has to be configured as an output
(DDB3 set (one)) to serve this function. The OC0 pin is also the output pin for the PWM
mode timer function.
• AIN0/INT2 – Port B, Bit 2
AIN0, Analog Comparator 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 Analog Comparator.
INT2, External Interrupt Source 2: The PB2 pin can serve as an external interrupt
source to the MCU.
• T1 – Port B, Bit 1
T1, Timer/Counter1 Counter Source.
• T0/XCK – Port B, Bit 0
T0, Timer/Counter0 Counter Source.
XCK, USART External Clock. The Data Direction Register (DDB0) controls whether the
clock is output (DDB0 set) or input (DDB0 cleared). The XCK pin is active only when the
USART operates in Synchronous mode.
Table 26 and Table 27 relate the alternate functions of Port B to the overriding signals
shown in Figure 26 on page 54. SPI MSTR INPUT and SPI SLAVE OUTPUT constitute
the MISO signal, while MOSI is divided into SPI MSTR OUTPUT and SPI SLAVE
INPUT.
58
ATmega32(L)
2503J–AVR–10/06
ATMEL [ ATMEL ]
