ATMEGA48V-10AUR 参数 Datasheet PDF下载

ATmega48/88/168

13.3.1

Alternate Functions of Port B

The Port B pins with alternate functions are shown in

Table 13-3.

Table 13-3.

Port Pin

PB7

Port B Pins Alternate Functions

Alternate Functions

XTAL2 (

Chip Clock Oscillator pin 2

)

TOSC2 (

Timer Oscillator pin 2

)

PCINT7 (Pin Change Interrupt 7)

XTAL1 (

Chip Clock Oscillator pin 1 or External clock input

)

TOSC1 (

Timer Oscillator pin 1

)

PCINT6 (Pin Change Interrupt 6)

SCK (SPI Bus Master clock Input)

PCINT5 (Pin Change Interrupt 5)

MISO (SPI Bus Master Input/Slave Output)

PCINT4 (Pin Change Interrupt 4)

MOSI (SPI Bus Master Output/Slave Input)

OC2A (Timer/Counter2 Output Compare Match A Output)

PCINT3 (Pin Change Interrupt 3)

SS (SPI Bus Master Slave select)

OC1B (Timer/Counter1 Output Compare Match B Output)

PCINT2 (Pin Change Interrupt 2)

OC1A (Timer/Counter1 Output Compare Match A Output)

PCINT1 (Pin Change Interrupt 1)

ICP1 (Timer/Counter1 Input Capture Input)

CLKO (Divided System Clock Output)

PCINT0 (Pin Change Interrupt 0)

PB6

PB5

PB4

PB3

PB2

PB1

PB0

The alternate pin configuration is as follows:

• XTAL2/TOSC2/PCINT7 – Port B, Bit 7

XTAL2: Chip clock Oscillator pin 2. Used as clock pin for crystal Oscillator or Low-frequency

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

TOSC2: Timer Oscillator pin 2. 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) and the EXCLK bit is cleared (zero) to enable asynchronous clock-

ing of Timer/Counter2 using the Crystal Oscillator, pin PB7 is disconnected from the port, and

becomes the inverting output of the Oscillator amplifier. In this mode, a crystal Oscillator is con-

nected to this pin, and the pin cannot be used as an I/O pin.

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

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