Q67120-C722 查看數據表（PDF） - Siemens AG

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Q67120-C722

High-Performance 8-Bit CMOS Single-Chip Microcontroller

Siemens AG 

SAB 80C517/80C537

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 = Input

O = Output

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

Semiconductor Group

8

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