SAB-80C517A-N18-T3 Просмотр технического описания (PDF) - Siemens AG

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SAB-80C517A-N18-T3

High-Performance 8-Bit CMOS Single-Chip Microcontroller

Siemens AG 

SAB 80C517A/83C517A-5

Pin Definitions and Functions (cont’d)

Symbol

Pin Number

I/O *) Function

P-LCC-84 P-MQFP-100-2

P3.0 - P3.7 21 - 28

90 - 97

I/O Port 3

is a bidirectional I/O port with internal pull-

up resistors. Port 3 pins that have 1 s

written to them are pulled high by the

internal pull-up resistors, and in that state

can be used as inputs. As inputs, port 3

pins being externally pulled low will source

current (IIL, in the DC characteristics)

because of the internal pull-up resistors.

Port 3 also contains the interrupt, timer,

serial port 0 and external memory strobe

pins that are used by various options. The

output latch corresponding to a secondary

function must be programmed to a one (1)

for that function to operate.

The secondary functions are assigned to

the pins of port 3, as follows:

– R × D0 (P3.0): receiver data input

(asynchronous) or data input/output

(synchronous) of serial interface

– T × D0 (P3.1): transmitter data output

(asynchronous) or clock output

(synchronous) of serial interface 0

– INT0 (P3.2): interrupt 0 input/timer 0

gate control

– INT1 (P3.3): interrupt 1 input/timer 1

gate control

– T0 (P3.4): counter 0 input

– T1 (P3.5): counter 1 input

– WR (P3.6): the write control signal

latches the data byte from port 0 into the

external data memory

– RD (P3.7): the read control signal

enables the external data memory to

port 0

* I = Input

O = Output

Semiconductor Group

9

1994-05-01

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