ATmega128 datasheet(75/386 Pages) ATMEL

75 / 386 page

2467S–AVR–07/09

ATmega128

• OC1B, 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.

• OC1A, Bit 5

OC1A, Output Compare Match A output: The PB5 pin can serve as an external output for the

Timer/Counter1 Output Compare A. The pin has to be configured as an output (DDB5 set (one))

to serve this function. The OC1A pin is also the output pin for the PWM mode timer function.

• OC0, Bit 4

OC0, Output Compare Match output: The PB4 pin can serve as an external output for the

Timer/Counter0 Output Compare. The pin has to be configured as an output (DDB4 set (one)) to

serve this function. The OC0 pin is also the output pin for the PWM mode timer function.

• MISO – Port B, Bit 3

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 DDB3. When the SPI is

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

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

• MOSI – Port B, Bit 2

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 DDB2. When the SPI is

enabled as a master, the data direction of this pin is controlled by DDB2. When the pin is forced

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

• SCK – Port B, Bit 1

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 DDB1. When the SPI is

enabled as a master, the data direction of this pin is controlled by DDB1. When the pin is forced

to be an input, the pull-up can still be controlled by the PORTB1 bit.

•SS – Port B, Bit 0

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

input regardless of the setting of DDB0. 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 DDB0.

When the pin is forced to be an input, the pull-up can still be controlled by the PORTB0 bit.

Table 31 and Table 32 relate the alternate functions of Port B to the overriding signals shown in

Figure 33 on page 71. SPI MSTR INPUT and SPI SLAVE OUTPUT constitute the MISO signal,

while MOSI is divided into SPI MSTR OUTPUT and SPI SLAVE INPUT.

ATmega128 Datasheet(PDF) 75 Page - ATMEL Corporation