AT90LS4433 datasheet(81/126 Pages) ATMEL

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AT90S/LS4433

1042H–AVR–04/03

Port D as General Digital I/O

PDn, General I/O pin: The DDDn bit in the DDRD Register selects the direction of this

pin. If DDDn is set (one), PDn is configured as an output pin. If DDDn is cleared (zero),

PDn is configured as an input pin. If PDn is set (one) when configured as an input pin,

the MOS pull-up resistor is activated. To switch the pull-up resistor off, the PDn has to

be cleared (zero) or the pin has to be configured as an output pin.The port pins are tri-

stated when a reset condition becomes active, even if the clock is not running.

Note:

1. n: 7,6..0, pin number.

Alternate Functions of Port D

• AIN1 – Port D, Bit 7

AIN1, Analog Comparator Negative Input. When configured as an input (DDD7 is

cleared [zero]), and with the internal MOS pull-up resistor switched off (PD7 is cleared

[zero]), this pin also serves as the negative input of the On-chip Analog Comparator.

During Power-down mode, the Schmitt trigger of the digital input is disconnected. This

allows analog signals, which are close to V

CC/2, to be present during Power-down with-

out causing excessive power consumption.

• AIN0 – Port D, Bit 6

AIN0, Analog Comparator Positive Input. When configured as an input (DDD6 is cleared

[zero]), and with the internal MOS pull-up resistor switched off (PD6 is cleared [zero]),

this pin also serves as the positive input of the On-chip Analog Comparator. During

Power-down mode, the Schmitt trigger of the digital input is disconnected. This allows

analog signals, which are close to V

CC/2, to be present during Power-down without

causing excessive power consumption.

• T1 – Port D, Bit 5

T1, Timer/Counter1 Counter Source. See the Timer description for further details

• T0 – Port D, Bit 4

T0: Timer/Counter0 Counter Source. See the Timer description for further details.

• INT1 – Port D, Bit 3

INT1, External Interrupt Source 1: The PD3 pin can serve as an external interrupt

source to the MCU. See the interrupt description for further details and how to enable

the source.

• INT0 – Port D, Bit 2

INT0, External Interrupt Source 0: The PD2 pin can serve as an external interrupt

source to the MCU. See the interrupt description for further details and how to enable

the source.

Table 27. DDDn Bits on Port D Pins

(1)

DDDn

PORTDn

I/O

Pull-up

Comment

Input

Tri-state (high-Z)

Input

Yes

PDn will source current if ext. pulled low.

Output

Push-pull Zero Output

Output

Push-pull One Output

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