C541U データシートの表示（PDF） - Siemens AG

部品番号

コンポーネント説明

メーカー

C541U

8-Bit CMOS Microcontroller

Siemens AG 

C540U

C541U

Table 2

Pin Definitions and Functions (cont’d)

Symbol

Pin Numbers

I/O*) Function

P-LCC-44 P-SDIP-52

P3.0 - P3.7 11, 13 - 19 13, 16 - 22 I/O Port 3

is an 8-bit quasi-bidirectional I/O port with internal

pullup resistors. Port 3 pins that have 1's written to

them are pulled high by the internal pullup resistors,

and in that state can be used as inputs. As inputs,

port 3 pins being externally pulled low will source

current (I IL, in the DC characteristics) because of

the internal pullup resistors. Port 3 also contains

the interrupt, timer, serial port 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:

P3.0 / LED2 LED2 output

P3.1 / DADD Device attached input

P3.2 / INT0 External interrupt 0 input /

timer 0 gate control input

P3.3 / INT1 External interrupt 1 input /

timer 1 gate control input

P3.4 / T0

Timer 0 counter input

P3.5 / T1

Timer 1 counter input

P3.6 / WR

WR control output; latches the

data byte from port 0 into the

external data memory

P3.7 / RD

RD control output; enables the

external data memory

XTAL2

20

23

– XTAL2

is the output of the inverting oscillator amplifier.

This pin is used for the oscillator operation with

crystal or ceramic resonator.

XTAL1

21

24

– XTAL1

is the input to the inverting oscillator amplifier and

input to the internal clock generator circuits.

To drive the device from an external clock source,

XTAL1 should be driven, while XTAL2 is left

unconnected. Minimum and maximum high and

low times as well as rise/fall times specified in the

AC characteristics must be observed.

*) I = Input

O = Output

Semiconductor Group

9

1997-10-01

Share Link: