AT90LS4433-4AI datasheet(72/126 Pages) ATMEL

72 / 126 page

AT90S/LS4433

1042H–AVR–04/03

I/O Ports

All AVR ports have true Read-Modify-Write functionality when used as general digital

I/O ports. This means that the direction of one port pin can be changed without uninten-

tionally changing the direction of any other pin with the SBI and CBI instructions. The

same applies for changing drive value (if configured as output) or enabling/disabling of

pull-up resistors (if configured as input).

Port B

Port B is a 6-bit bi-directional I/O port.

Three I/O memory address locations are allocated for the Port B, one each for the Data

B Input Pins – PINB, $16($36). The Port B Input Pins address is read only, while the

Data Register and the Data Direction Register are read/write.

All port pins have individually selectable pull-up resistors. The Port B output buffers can

sink 20 mA and thus drive LED displays directly. When pins PB0 to PB7 are used as

inputs and are externally pulled low, they will source current if the internal pull-up resis-

tors are activated.

The Port B pins with alternate functions are shown in Table 23.

When the pins are used for the alternate function, the DDRB and PORTB Registers

have to be set according to the alternate function description.

Port B Data Register – PORTB

Port B Data Direction Register

– DDRB

Port B Input Pins Address –

PINB

Table 23. Port B Pin Alternate Functions

Port Pin

Alternate Functions

PB0

ICP (Timer/Counter1 Input Capture Pin)

PB1

OC1 (Timer/Counter1 Output Compare Match Output)

PB2

SS (SPI Slave Select Input)

PB3

MOSI (SPI Bus Master Output/Slave Input)

PB4

MISO (SPI Bus Master Input/Slave Output)

PB5

SCK (SPI Bus Serial Clock)

Bit

76543210

$18 ($38)

–

PORTB5

PORTB4

PORTB3

PORTB2

PORTB1

PORTB0

PORTB

Read/Write

R/W

Initial Value

00000000

Bit

76543210

$17 ($37)

–

DDB5

DDB4

DDB3

DDB2

DDB1

DDB0

DDRB

Read/Write

R/W

Initial Value

00000000

Bit

76543210

$16 ($36)

–

PINB5

PINB4

PINB3

PINB2

PINB1

PINB0

PINB

Read/Write

RRRRRRRR

Initial Value

N/A

AT90LS4433-4AI Datasheet(PDF) 72 Page - ATMEL Corporation

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