温室大棚控制系统外文翻译

外文文献及译文学院：电气与控制工程学院班级：测控技术与仪器1002班姓名：学号：指导老师：The

single-chip

microcomputer

is

the

culmination

of

both

the

development

of

the

digital

computer

and

the

integrated

circuit

arguably

the

tow

most

significant

inventions

of

the

20th

century

.These

tow

types

of

architecture

are

found

in

single-chip

microcomputer.

Some

employ

the

split

program/data

memory

of

the

Harvard

architecture,

others

follow

the

philosophy,

widely

adapted

for

general-purpose

computers

and

microprocessors,

of

making

no

logical

distinction

between

program

and

data

memory

as

in

the

Princeton

architecture.In

general

terms

a

single-chip

microcomputer

is

characterized

by

the

incorporation

of

all

the

units

of

a

computer

into

a

single

device.

ROM

is

usually

for

the

permanent,

non-volatile

storage

of

an

applications

program

.Many

microcomputers

and

microcontrollers

are

intended

for

high-volume

applications

and

hence

the

economical

manufacture

of

the

devices

requires

that

the

contents

of

the

program

memory

be

committed

permanently

during

the

manufacture

of

chips

.

Clearly,

this

implies

a

rigorous

approach

to

ROM

code

development

since

changes

cannot

be

made

after

manufacture

.This

development

process

may

involve

emulation

using

a

sophisticated

development

system

with

a

hardware

emulation

capability

as

well

as

the

use

of

powerful

software

tools.

Some

manufacturers

provide

additional

ROM

options

by

including

in

their

range

devices

with

(or

intended

for

use

with)

user

programmable

memory.

The

simplest

of

these

is

usually

device

which

can

operate

in

a

microprocessor

mode

by

using

some

of

the

input/output

lines

as

an

address

and

data

bus

for

accessing

external

memory.

This

type

of

device

can

behave

functionally

as

the

single

chip

microcomputer

from

which

it

is

derived

albeit

with

restricted

I/O

and

a

modified

external

circuit.

The

use

of

these

ROM

less

devices

is

common

even

in

production

circuits

where

the

volume

does

not

justify

the

development

costs

of

custom

on-chip

ROM;there

can

still

be

a

significant

saving

in

I/O

and

other

chips

compared

to

a

conventional

microprocessor

based

circuit.

More

exact

replacement

for

ROM

devices

can

be

obtained

in

the

form

of

variants

with

'piggy-back'

EPROM(Erasable

programmable

ROM

)sockets

or

devices

with

EPROM

instead

of

ROM.These

devices

are

naturally

more

expensive

than

equivalent

ROM

device,

but

do

provide

complete

circuit

equivalents.

EPROM

based

devices

are

also

extremely

attractive

for

low-volume

applications

where

they

provide

the

advantages

of

a

single-chip

device,

in

terms

of

on-chip

I/O,

etc.

,with

the

convenience

of

flexible

user

programmability.The

CPU

is

much

like

that

of

any

microprocessor.

Many

applications

of

microcomputers

and

microcontrollers

involve

the

handling

of

binary-coded

decimal

(BCD)

data

(for

numerical

displays,

for

example)

,hence

it

is

common

to

find

that

the

CPU

is

well

adapted

to

handling

this

type

of

data

.It

is

also

common

to

find

good

facilities

for

testing,

setting

and

resetting

individual

bits

of

memory

or

I/O

since

many

controller

applications

involve

the

turning

on

and

off

of

single

output

lines

or

the

reading

the

single

line.

These

lines

are

readily

interfaced

to

two-state

devices

such

as

switches,

thermostats,

solid-state

relays,

valves,

motor,

etc.Parallel

input

and

output

schemes

vary

somewhat

in

different

microcomputer;

in

most

a

mechanism

is

provided

to

at

least

allow

some

flexibility

of

choosing

which

pins

are

outputs

and

which

are

inputs.

This

may

apply

to

all

or

some

of

the

ports.

Some

I/

The

DS18B20

Digital

Thermometer

provides

9

to

12-bit

(configurable)

temperature

readings

which

indicate

the

temperature

of

the

device.

Information

is

sent

to/from

the

DS18B20

over

a

1-Wire

interface,

so

that

only

one

wire

(and

ground)

needs

to

be

connected

from

a

central

microprocessor

to

a

DS18B20.

Power

for

reading,

writing,

and

performing

temperature

conversions

can

be

derived

from

the

data

line

itself

with

no

need

for

an

external

power

source.

Because

each

DS18B20

contains

a

unique

silicon

serial

number,

multiple

DS18B20s

can

exist

on

the

same

1-Wire

bus.

This

allows

for

placing

temperature

sensors

in

many

different

places.

Applications

where

this

feature

is

useful

include

HVAC

environmental

controls,

sensing

temperatures

inside

buildings,

equipment

or

machinery,

and

process

monitoring

and

control.

The

block

diagram

of

Figure

1

shows

the

major

components

of

the

DS18B20.

The

DS18B20

has

four

main

data

components:

1)

64-bit

laser

ROM,

2)

temperature

sensor,

3)

nonvolatile

temperature

alarm

triggers

TH

and

TL,

and

4)

a

configuration

register.

The

device

derives

its

power

from

the

1-Wire

communication

line

by

storing

energy

on

an

internal

capacitor

during

periods

of

time

when

the

signal

line

is

high

and

continues

to

operate

off

this

power

source

during

the

low

times

of

the

1-Wire

line

until

it

returns

high

to

replenish

the

parasite

(capacitor)

supply.

As

an

alternative,

the

DS18B20

may

also

be

powered

from

an

external

3V

-

5.5V

supply.

Communication

to

the

DS18B20

is

via

a

1-Wire

port.

With

the

1-Wire

port,

the

memory

and

control

functions

will

not

be

available

before

the

ROM

function

protocol

has

been

established.

The

master

must

first

provide

one

of

five

ROM

function

commands:

1)

Read

ROM,

2)

Match

ROM,

3)

Search

ROM,

4)

Skip

ROM,

or

5)

Alarm

Search.

These

commands

operate

on

the

64-bit

laser

ROM

portion

of

each

device

and

can

single

out

a

specific

device

if

many

are

present

on

the

1-Wire

line

as

well

as

indicate

to

the

bus

master

how

many

and

what

types

of

devices

are

present.

After

a

ROM

function

sequence

has

been

successfully

executed,

the

memory

and

control

functions

are

accessible

and

the

master

may

then

provide

any

one

of

the

six

memory

and

control

function

commands.

单片机是数字计算机的开发和集成电路20世纪可以说是拖最显著的发明之大成体系结构，这些纤维束类型被发现在单芯片微型计算机。一些采用了哈佛结构的分割程序/数据存储器，别人遵守的理念，广泛适用于通用计算机和微处理器，使得程序和数据存储器之间没有逻辑的区别在普林斯顿体系结构。笼统的单芯片微型计算机，其特征在于通过计算机的所有单位纳入一个单一的设备。ROM是通常的永久性的，非应用程序的易失性存储器。不少微机和单片机用于大批量应用，因此，经济的设备制造要求的程序存储器的内容是在制造期间永久性的刻录在芯片中，这意味着严谨的方法，因为修改ROM代码不能制造之后发展。这一发展过程可能涉及仿真,使用硬件仿真功能以及强大的软件工具使用先进的开发系统。

一些制造商在其提供的设备包括的范围（或拟使用）用户可编程内存.其中最简单的通常是设备能够运行于微处理器模式通过使用一些输入/输出作为地址线额外的ROM选项和数据总线访问外部内存.这种类型的设备可以表现为单芯片微型计算机尽管有限制的I/O和外部修改这些设备的电路.小内存装置的应用是非常普遍的在永久性内存的制造中;但仍然可以在我节省大量成本I/O和其它芯片相比，传统的基于微处理器电路.更准确的ROM设备更换，可在与'形式变种背驮式'EPROM（可擦除可编程只读存储器）插座或存储器，而不是ROM器件。这些器件自然价格比同等ROM设备贵，但不提供完整的等效电路.EPROM的设备也非常有吸引力对于低容量应用中，他们提供的单芯片器件的优势，在以下方面的板载I/O等，在灵活的用户可编程带来的便利。CPU是很象微型电子计算机和微控制器的任何微电脑.许多微电脑和微控制器涉及到二进制编码(十进制处理（BCD）的数据为例）数字显示，因而，常常可以发现该CPU是很适合处理这种类型的数据。对设施良好与否进行的测试，设置和重置单个位的内存或I/O控制器的应用程序，也是常见的因为许多涉及打开和关闭的单输出线或在单线.这些线很容易连接到二进制的设备，如开关，恒温器，固态继电器，阀门，电机等。并行输入和输出的计划有所不同，在不同的微机，在大多数设立一个机制，至少选择让其中一些引脚输出，一些引脚输如是非常灵活的。这可能适用于所有或端口.有些I/O线直接连接到适当的设备，例如，荧光显示器，也可以提供足够的电流，使接口和其他设备直接相连.一些设备允许一个I/O端口,其他组件将作为系统总线配置为允许片外存储器和I/O扩展。这个设施是潜在有用的一个产品系列的发展，因为连续增强可能成为太上存储器，这是不可取的，不是建立在现有的软件基础上的。串行通信是指与终端设备的链接使用少量的通讯线.这种通讯也可利用特殊的接口连接功能芯片使几个微型机连在一起。双方共同异步同步通信方案要求的规则提供成帧（启动和停止）的信息。这可以作为一个硬件设施或U（拧）艺术（通用执行（同步）异步接收器/发送器）减轻处理器（和应用程序）的这种低层次的确费时.它也只需要选择一个波特率及其他可能的选择（停止位，奇偶校验等）和负载号码（或读取），串行发送器（或接收）的缓冲器.进行适当的格式的数据串行处理，然后由硬件电路完成。该DS18B20数字温度计提供9位至12位摄氏温度测量，并与非易失性用户可编程上下触发点报警功能。DS18B20的通信通过一个1-Wire总线，按照定义，只需要一个数据线（和地线）与中央微处理器通信。它具有-55°C至+125°C的工作温度范围，精确到±0.5°C在-10°C至+85°C。此外，DS18B20可以直接从数据线（“寄生电源”）获得电力，省去了外部电源。每个DS18B20都有一个唯一的64位序列码，它允许多个DS18B20s到相同的1-Wire总线上运行。因此，它是简单的使用一个微处理器来控制分布在大面积上许多DS18B20s。应用可以受益于这个功能包括HVAC环境控制，建筑物内部的温度监测系统，设备或机械，过程监测和控制系统。该DS18B20可以通过在VDD引脚上的外部电源供电，也可以在“寄生供电”模式，它允许DS18B20来没有本地外部电源正常工作。寄生电源是用于需要远程温度传感或应用程序非常有用非常空间受限。图1显示了DS18B20的寄生功率控制电路，其中“偷”的力量从1-Wire总线通过DQ针时总线高。失窃的主管权力的DS18B20在总线处于高，一些电荷存储在寄生电源电容（CPP）提供电源时，总线低。当DS18B20采用的是寄生供电模式，VDD引脚必须连接到地面。在寄生供电模式，在1-Wire总线和CPP能够提供足够的电流，以DS18B20的大多数操作，只要满足指定的时间和电压要求（见DC电气特性和AC电气特性）。然而，DS18B20从暂存存储器进行温度转换或复制数据时，EEPROM时，工作电流可高达1.5毫安。该电流可能会造成整个弱1-Wire上拉电阻不可接受的电压降，是更多的电流比可通过CPP提供。为了确保DS18B20的有足够的电源电流，就必须提供1-Wire总线强上拉每当温度转换正在发生或数据被复制暂存器到EEPROM中。这可以通过使用一个MOSFET直接拉路公交车到铁路如图4来完成。一个转换T[44H]或复制暂存器[后的1-Wire总线必须切换到的10μs内强上拉（最大）48小时]命令发出，而总线必须转换（tCONV时间）或数据传输（TWR=10ms）的持续时间高举的上拉。而拉启用没有其他活动可以采取的1-Wire总线上的地方。该DS18B20也可通过连接外部电源为VDD端子，如图5的传统方法提供动力。这种方法的优点是，不需要在MOSFET上拉，并在1-Wire总线空闲时，以过程中的温度转换时间进行其它流量。不建议使用寄生电源的温度高于100°C，因为DS18B20可能无法维持通讯由于能够在这些温度下存在较高的漏电流。对于应用中，这样的温度是可能的，强烈建议DS18B20由外部电源供电。在某些情况下，总线主机可能不知道总线上的DS18B20s是否是寄生虫供电或由外部供应。主需要这个信息来确定是否应在温度转换中使用的强大的总线上拉。要获得这些信息，主机可以发出跳过ROM[CCH]命令，接着读电源[B4H]命令后面加上一个“读时隙”。在读时隙，寄生虫供电DS18B20s将拉动总线低，外部供电DS18B20s会让总线仍然很高。如果总线被拉低，主人知道它必须在温度转换提供强上拉的1-Wire总线上。当你准备选择一个温度传感器，你不再局限于一个模拟输出或数字输出设备。现在有一个广泛选择的传感器类型，其中之一应该符合你的系统的需求。直到最近，市场