Rainbow-electronics AT90LS4433 Manual do Utilizador descarregar pdf (Página 82)

AT90S/LS4433

1042G–AVR–09/02

• TXD – Port D, Bit 1

Transmit Data (Data Output pin for the UART). When the UART Transmitter is enabled,

this pin is configured as an output, regardless of the value of DDD1.

• RXD – Port D, Bit 0

Receive Data (Data Input pin for the UART). When the UART Receiver is enabled, this

pin is configured as an input, regardless of the value of DDD0. When the UART forces

thispintobeaninput,alogical“1” in PORTD0 will turn on the internal pull-up.

Port D Schematics Note that all port pins are synchronized. The synchronization latches are, however, not

shown in the figures.

Figure 57. Port D Schematic Diagram (Pin PD0)

DATA BUS

RESET

MOS

PULL-

PD0

RXD

RXEN

WP:

WD:

RL:

RP:

RD:

RXD:

RXEN:

WRITE PORTD

WRITE DDRD

READ PORTD LATCH

READ PORTD PIN

READ DDRD

UART RECEIVE DATA

UART RECEIVE ENABLE

DDD0

PORTD0

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