(完整版)Singlechipmicrocomputerandthedevelopmentofthetemperatur

Single chip microcomputer and the development of the

temperature and humidity sensor

Born

in

the

1970

s

single

chip

microcomputer,

and

experience

the

SCM,

MCU, SOC three phases.

(1) SCM namely Single Chip computer stage, main is to seek out the

monolithic

forms

of

the

embedded

system

best

system

structure.

different development road.

(2) MCU namely Micro Controller (Micro Controller Unit) stage, the

main technological development direction is: expanding meet embedded

application,

the

object

system

requirements

of

various

peripheral

circuit

and interface circuit, dash forward show its object the intelligent

control ability.

(3) MCU is embedded system independent development way, to a key

factor to the development

of MCU stage,

is to seek

application system on

a

chip

in

the

maximization

of

the

solution;

Therefore,

special

MCU

development

natural

form

the

SOC

tendency.

With

microelectronics

technology, IC design, EDA tools development, based on the single chip

microcomputer

application

system

SOC

design

can

have

larger

development.

Temperature is a basic physical quantities, everything in nature is

closely related with the process of temperature. The temperature sensor

is the earliest development, the most widely used kind of sensor. From

17

th

century

people

began

to

use

temperature

measuring.

The

temperature

sensor

there

are

four

main

types:

thermocouple,

thermal

resistance,

resistance

temperature

detector

(RTD)

and

temperature

sensor

IC.

IC

temperature sensor and including analog output and digital output two

types. Contact temperature sensor detection part and the tested object

has a good contact, and calls the thermometer. The thermometer through

the transmission or convection reach thermal equilibrium, thus make the

thermometer and value can be measured directly says the temperature of

the objects. General measurement precision. In a certain temperature

range,

the

thermometer

can

also

be

measuring

objects

of

internal

temperature distribution. But for sports body, small target or heat

capacity is very small objects will produce larger measurement error,

commonly used a thermometer have two- metal thermometer, glass liquid

thermometer,

pressure

type

thermometer,

resistance

thermometers,

thermistors

and

temperature

difference

electric

dipole,

etc.

Contactless

temperature sensor sensitive components and tested object each other is

not

contact,

again

say

non-contact

table.

This

instrument

can

be

used

to

measure

movement

object,

small

goals

and

heat

capacity

small

or

temperature

change

quickly

(transient)

the

surface

temperature

of

the

object,

also

can

used

for

the

measurement

of

the

temperature

distribution.

89S52 devices profile

The main performance: and MCS-51 SCM products compatible, and 8 K

bytes

in

the

system

programmable

Flash

memory,

1000

time

period,

and

the

static

operation:

0

Hz

~

33

Hz,

level

3

encryption

program

memory, 32 programmable I/O mouth line, three 16 timer/counters, eight

interrupt

source,

full-duplex

UART

serial

channel,

low

power

dissipation

power lost mode, and free after power off interrupt can wake up, the

watchdog timer, double data pointer, off the identifier.

Functional characteristics description: AT89S52 devices is a low

power, high-performance CMOS 8-bit microcontrollers, with 8 K in system

programmable Flash memory. Atmel company use high-density nonvolatile

technology manufacturing, and industry 80 C51 product instructions and

pin fully compatible. Chip Flash allow program memory in the system

programmable, also suitable for conventional programming console. In a

single

chip,

with

clever

8

bits

CPU

and

in

the

system

programmable

Flash,

make AT89S52 devices for many embedded control system to provide high

flexible application, super efficient solution. AT89S52 devices has the

following standard function: 8 k bytes Flash, 256 bytes RAM, 32 bit I/O

mouth

line,

the

watchdog

timer,

two

data

pointer,

three

16

timer/counter,

a

6

vector

level

2

interrupt

structure,

full-duplex

serial

mouth,

within

crystals

of

timely

clock

circuit.

In

addition,

AT89S52

devices

can

be

down

to 0 Hz series static logic operation, support two software can choose

power saving mode. Idle mode, the CPU to stop working, and allow RAM,

timer/counter, serial ports, interrupt continue to work for. Power lost

protection

ways,

a

RAM

content

being

saved,

has

been

frozen,

SCM

all

work

stop, until the next an interrupt or hardware reset so far.

ated temperature sensorAD590

Integrated temperature sensor AD590 to, its temperature resolution

for the 0.3 degrees Celsius. The analog signal is output AD590 to, when

the

temperature

of

0

degrees,

output

current

273.2

microamps,

and

current

variation

and

temperature

variation

in

a

linear

relationship,

temperature,

and

once

every

change,

the

output

current

change

1

microamps,

the

temperature

sensor

of

working

temperature

range

is-30

degrees-150

degrees.

If use AD590 to make the temperature sensor, sensor peripheral circuit

is simple, just put sampling resistance and AD590 to link and then to

amplify

the

signal,

and

then

using

voltage

comparator

compared

to

output

voltage, voltage comparator output signals can be directly as PLC the

input signal.

ty sensor

There are many ways of measuring the air humidity, its principle is

based on certain material from the surrounding air absorb water caused

by physical or chemical properties of the change, indirectly from the

material of water quantity and the surrounding air humidity. Capacitive