ATmega48 datasheet(71/340 Pages) ATMEL

71 / 340 page

7530H–AVR–02/09

ATmega48/88/168 Automotive

PCINT7: Pin Change Interrupt source 7. The PB7 pin can serve as an external interrupt source.

If PB7 is used as a clock pin, DDB7, PORTB7 and PINB7 will all read 0.

• XTAL1/TOSC1/PCINT6 – Port B, Bit 6

XTAL1: Chip clock Oscillator pin 1. Used for all chip clock sources except internal calibrated RC

Oscillator. When used as a clock pin, the pin can not be used as an I/O pin.

TOSC1: Timer Oscillator pin 1. Used only if internal calibrated RC Oscillator is selected as chip

clock source, and the asynchronous timer is enabled by the correct setting in ASSR. When the

AS2 bit in ASSR is set (one) to enable asynchronous clocking of Timer/Counter2, pin PB6 is dis-

connected from the port, and becomes the input of the inverting Oscillator amplifier. In this

mode, a crystal Oscillator is connected to this pin, and the pin can not be used as an I/O pin.

PCINT6: Pin Change Interrupt source 6. The PB6 pin can serve as an external interrupt source.

If PB6 is used as a clock pin, DDB6, PORTB6 and PINB6 will all read 0.

• SCK/PCINT5 – Port B, Bit 5

SCK: Master Clock output, Slave Clock input pin for SPI channel. 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.

PCINT5: Pin Change Interrupt source 5. The PB5 pin can serve as an external interrupt source.

• MISO/PCINT4 – Port B, Bit 4

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 DDB4. When the SPI is

enabled as a Slave, the data direction of this pin is controlled 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.

PCINT4: Pin Change Interrupt source 4. The PB4 pin can serve as an external interrupt source.

• MOSI/OC2/PCINT3 – Port B, Bit 3

MOSI: SPI Master Data output, Slave Data input for SPI channel. When the SPI is enabled as a

Slave, this pin is configured as an input regardless of the setting of DDB3. When the SPI is

enabled as a Master, the data direction of this pin is controlled by DDB3. When the pin is forced

by the SPI to be an input, the pull-up can still be controlled by the PORTB3 bit.

OC2, Output Compare Match Output: The PB3 pin can serve as an external output for the

Timer/Counter2 Compare Match. The PB3 pin has to be configured as an output (DDB3 set

(one)) to serve this function. The OC2 pin is also the output pin for the PWM mode timer

function.

PCINT3: Pin Change Interrupt source 3. The PB3 pin can serve as an external interrupt source.

•SS/OC1B/PCINT2 – Port B, Bit 2

SS: Slave Select input. When the SPI is enabled as a Slave, this pin is configured as an input

regardless of the setting of DDB2. 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 controlled by DDB2. When

the pin is forced by the SPI to be an input, the pull-up can still be controlled by the PORTB2 bit.

ATmega48 Datasheet(PDF) 71 Page - ATMEL Corporation