Mechanical Refrigeration System

In refrigrasi mechanical vapor compression systems are a series of four main components: evaporator, compressor, condenser, and refrigerant flow control devices. Each component has a trait and its own function differently, but in an integrated and operate together will be able to move the thermal energy.

The impact of operating a refrigeration system on an object is, if picked up some of the energy contained in it, the temperature of the object will decrease. Conversely, because the refrigeration system operation is then a number of displaced thermal energy to the environment, the environment can become warmer.

The following is a brief description of the main components of a mechanical refrigeration system:

1. Condenser (condenser - CD)

Condenser is the component where the refrigerant phase change process occurs, the vapor phase into liquid phase. From the process of condensation (condensation) that occur in it that was then this component gets its name. The process of condensation will take place when the refrigerant to release the heat it contains.

Heat is released and discharged into the environment. In order for heat to escape into the environment, then the condensation temperature (TKD) should be higher than the ambient temperature (Tling). Because the refrigerant is a substance that is very volatile, so for him to be made of high pressure condensed. Thus, the condenser is the part where the high-pressure refrigerant (PKD = high pressure - HP).

2. Counterfeit expansion (expansion devices - Exd)

This tool serves as a gate that regulates how much liquid refrigerant is allowed to flow from the condenser to the evaporator. Therefore these tools are often also called refrigerant flow controller. In various textbooks of thermodynamics, processes occurring in these devices is usually called a throttling process.

The amount of refrigerant flow rate is one factor that determines the amount of refrigeration capacity. For a small refrigeration system, the refrigerant flow rate required is also small. Instead the unit or a large refrigeration system will have large refrigerant flow rate as well. There are several types of expansion devices. Below is assigned to some of them.

a. Capillary tube (capillary tube - CT).

Form of copper pipe with holes smaller than about 1 mm in diameter, with height adjusted with keperluannya up to several meters. At various refrigeration units that use these pipes are usually strung to protect them from damage and compact placement.

Hole narrow channel and capillary tube length is an obstacle to the flow of refrigerant through it; barriers that limit the amount of flow that's it. This capillary tube produces a constant flow.

b. Hand expansion valve (hand / manual expansion valve - HEV).

It is a form of flow regulator valve or faucet used to, which is operated to adjust the opening manually.

c. Thermostatic expansion valve (thermostatic expansion valve - TEV).

In this device there are parts that can work thermostatic, which has a temperature sensor attached to the output of the evaporator. Temperature changes that occur at the output of the evaporator is a major indicator of small refrigeration load. Temperature variation was used to set the aperture TeV, so that the flow rate through it also be controlled.

d. Float valve (float valve - FV).

Expansion devices of this type is usually coupled with the evaporator type of 'puddle' (flooded evaporator, wet evaporator). Height (level) of fluid in the reservoir (reservoir) to drive the evaporator liquid that floats into the regulator valve opening.

3. Evaporator (evaporator - EV)

Evaporator is the component where the liquid refrigerant that goes into it will evaporate. The process of vaporization (evaporation), it occurs because the liquid refrigerant absorbs heat, ie refrigeration system which is a burden. There are two types of evaporators are:

a. Direct expansion evaporators (direct / dry expansion type - DX).

In this evaporator there is a section, namely at the output, which is designed always awake 'dry', meaning in part that the berfasa liquid refrigerant evaporates before it has been sucked out into the compressor inlet.

b. Evaporator inundation (flooded / wet expansion type).

In this type of evaporator entire inner surface of the evaporator is always flooded, or touching, with the refrigerant is a liquid. There is a reservoir (reservoir, low pressure receiver), where the liquid refrigerant collected, and from the top of the reservoir the refrigerant vapor formed in the evaporator is sucked into the compressor.

4. Compressor (compressor - CP)

 The compressor is a component which is the heart of the refrigeration system. Compressors work sucking the refrigerant vapor from the evaporator and pushed by means of compression to flow into the condenser.

Because the refrigerant compressor drain device expansion while restricting the flow, then in between these two components were stirred pressure difference, namely: the condenser refrigerant pressure is high (high pressure - HP), while in the evaporator refrigerant pressure is low (low pressure - LP).

Mechanical Refrigeration System

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PLC (Programmable Logic Controller) - An Introduction

PLC (Programmable Logic Controller) was first introduced in 1969 by Richard E. Morley who was the founder of Modicon Corporation. According to the National Electrical Manufacturing Association (NEMA) PLC is defined sebagasi a digital electronic device with a programmable memory to store instructions that perform specific functions such as logic, sequence, timing, counting, and arithmetic to control an industrial machine or process in accordance with the desired industry.

PLC is capable of doing a continuous process based on input variables and provide the programming decisions at will so that the value of output under control.

PLC is a "special computer" for applications in industry, to monitor the process, and to replace the hard wiring controls and has its own programming language. But the PLC is not the same because the PLC will be a personal computer designed for installation and maintenance by a technician and an electrician in the industry who do not have to have a high electronics skills and provide flexibility based on the instruction execution control logic.

That's why the PLC is increasingly well developed in terms of number of inputs and outputs, the amount of available memory, speed, communication between the PLC and how or programming techniques. Almost all kinds of production processes in industry can be automated using a PLC.

The speed and accuracy of operation can be increased so much better using this control system. The advantage of PLC is its ability to change and replicate the process at the same operation with the communication and information-gathering vital information.


Operations on the PLC consists of four essential parts:

1. observation value of inputs

2. run program

3. provides output value

4. control

From an excess of PLC also has shortcomings, among others, which often highlighted is that to program a PLC takes someone who is skilled and fully understands what is needed by the plant and understand about the security or safety that must be met.

Meanwhile, a trained person like that is quite rare and the programming must be made directly to the place where the servers are connected to the PLC, while it is not unusual location of the computer playing it in dangerous places. Therefore we need a device capable of observing, edit and run programs remotely.

PLC (Programmable Logic Controller) - An Introduction

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Temperature data acquisition using microcontroller

Abstract
This paper discusses the design of the temperature data acquisition system that uses a component-konponen basic form of a temperature sensor, microcontroller and LCD as the viewer facility. Temperature data acquisition system into the one thing that is very important in industrial activity, because it is a small part of a process control.

With regard to the importance of the system, then the design temperature data acquisition system capable of monitoring the temperature of a plant. Data to be measured is a temperature so that the physical quantities to be processed and displayed in the form of electrical systems used LM35 temperature sensor that is able to convert these quantities with the increase of 10mV / º C.

To be able to design the system was first carried out the process to change the temperature into an analog voltage using a temperature sensor LM35. After going through the process boosted by the signal conditioning, analog voltage is converted into digital data using the ADC 0804.

Digital data acquired and processed by the microcontroller AT89S51 and displayed, so that got a plant with information about the temperature unit ° C on an LCD. From the temperature data acquisition system design showed that this system has the ability to measure the temperature from 25 º C to 100 º C with an average error of 0.2125 appointment temperature ° C.

Keywords: Acquisition of temperature data, LM35 temperature sensor, microcontroller AT89S51

I. INTRODUCTION

1.1 Background
Instrumentation systems that form the data acquisition has been widely used in industrial activities, as part of the process control. Measurement of physical quantities is one step in the acquisition of data.

Temperature is one of the physical quantities are often used in a control system is good only for a monitoring system alone or to further control the process.

In connection with this, then we make a temperature sensor that can be controlled by a microcontroller. By displaying a measurement result digitally, monitoring of the process can be conducted more easily.

1.2.1 Objectives
Designing a data acquisition system for temperature and then displayed on the LCD using a Microcontroller AT89S51.


1.3 Limitation Problem
In making this task the authors limited the problem as follows:
1. Range data acquisition is 25 º C to 100 º C.
2. Measurement data is displayed on an LCD as the monitoring equipment without performing process control.
3. ADC configuration set free running.

II. BASIC THEORY

2.1.1 Temperature Sensor LM 35
To detect the temperature used an LM 35 temperature sensor that can be directly calibrated in ° C, the LM 35 is functioned as the basic temperature sensors. Vout from the LM 35 is associated with ADC (Analog To Digital Converter). In room temperature (25 ° C) transducer is capable of removing the voltage 250mV and 1.5 V at a temperature of 150 ° C with an increase of 10mV / ° C.

2.2 Operational Amplifiers (Operational Amplifiers)
Operational amplifiers are integrated circuits (IC) which has 5 basic terminal. Two terminals for power supply, 2 the other is used for the input signal in the form of reverse input (-) and no reverse input (+) and 1 terminal for output.

2.2.1 No Reverse Amplifier (Non-inverting Amplifier)
Not reverse the amplifier is an amplifier where output voltage or the Vo have the same polarity or input voltage Vi. I currents flowing into the Ri as input impedance op - amp is very large so that no current flows on both the input terminals. Voltage at Ri equal to Vi because of differences in the two terminal input voltage approaches 0 V.
i = (2.5)

Voltage at Rf can be expressed as
VRF = I Rf = (2.6)
The output voltage Vo is obtained by adding the voltage at which Ri Vi to the voltage at the Rf of VRF.
Vo = Vi + Vi (2.7)

2.2.2 Differential Amplifier
Differential amplifier is an amplifier where output voltage or the Vo is the result of the difference between the two pieces of input voltage at the inverting terminal and non-invertingnya.

2.3 The series of Analog to Digital Converter (ADC)
ADC in this design is used to convert the input analog output temperature sensor that has been amplified into 8-bit digital data. Type ADC ADC 0804 is used in working mode free running. To create a working mode into free running ADC 0804, it must be known how the sequence of values ​​on and change the value on.

Working mode free running ADC is obtained if and connected to ground in order to always get a logic 0 so that the ADC will always be active and ready to provide data. Pin and rolled into one because of changes in the same logic on logic changes, thus providing the logic to be done automatically by the output.

2.4 Microcontroller AT89S51
AT89S51 is an 8 bit microcontroller is made of CMOS, which is to consume low power and high ability. This microcontroller has a 4Kbyte In-System Programmable Flash Memory, RAM is 128 bytes, 32 input / output, watchdog timer, two data registers pointers, two 16-bit timers and counters, five interrupt vectors, a full-duplex serial port, on-chip oscillator and clock circuit.

AT89S51 made with non-volatile memory technology with high density by Atmel. Microcontroller is suitable to the instruction set and pinout industry standard 80C51.
On-chip flash memory allows the program to re-programmed with the usual nonvolatile memory programmer.

Description:
Vcc: Supply Voltage
GND: Ground or earth
RST: Reset input. Condition logic '1 'during the engine cycle when the oscillator work and will reset the microcontroller in question.
Function - function Port:
Port 0: 8 bit parallel port is open drain in both directions. When used to access the external memory, this port will memultipleks memory address with the data.
Port 1: an 8-bit parallel port, two-way that can be used for various purposes.
Port 2: an 8-bit wide parallel port is bidirectional. These ports make deliveries byte address when done accessing external memory.

P3.0: Shared serial input
P3.1: saluaran serial output
P3.2: External Interrupt 0
P3.3: External Interrupt 1
P3.4: Input external timer / counter 0
P3.5: Input external timer / counter 1
P3.6: Signal punctuation ekstrenal data memory.
P3.7: Signal sign write external data memory.

III. DESIGN SYSTEM

3.1 Hardware Design

3.1.1 Temperature Sensor (LM35)
LM35 temperature sensor serves to change the temperature of physical quantities in the form of a magnitude electrical voltage. This sensor has a parameter that each increase of 1 º C increase by 10mV of output voltage with a maximum limit of the sensor output is 1.5 V at a temperature of 150 ° C.

In the design we set the adc output reaches full scale when the temperature of 100 ° C, so that when the temperature is 100 ° C. The transducer output voltage (10mV / ° C x 100 ° C) = 1V.
From direct current measurements at room temperature, LM35 output is 0.3V (300mV). This voltage is processed by using a signal conditioning circuit to match the ADC input stage.

3.1.2 Signal conditioning
Signal conditioner works to strengthen the LM35 temperature sensor output voltage to be able to be processed on the next equipment in this case by the ADC 0804.
Desirable that the temperature measurement can be performed in the range of 25 ° C - 100 ° C, whereas at room temperature LM35 has issued a voltage of 0.3 V, so to be able to arrange for the ADC input at 0V at room temperature, added a differential amplifier.

Differential amplifier output boosted again with the non-inverting amplifier circuit. With Vin = 1V at 100 ° C and the desired Vout at 5V (VX) are used to determine the value of resistance to non-inverting amplifier as follows:

If Ri = 1K then, Rf = 4K 50K potentiometer is used in applications for Rf.

3.1.3 Analog to Digital Converter (ADC 0804)
Adc circuit design to be used mode free running. This mode was chosen because of adc conversion time is much faster on the level of temperature change of the plant, so that every time the temperature changes, adc always been completed to convert the data so that data is valid for sampled.

For ADC 0804 with the number of bits by 8 bits and Vref = 5V then the resolution (ΔV) = 5 x 2-8 = 19.53 mV.
Adc analog voltage input from the output at full scale signal conditioning in the amount of VX can be calculated as follows:
thus when the input voltage adc adc output would be worth 4.9804 FFH.


3.1.4 Microcontroller (AT89S51)
8 bit digital data from the ADC is taken by mikokontroller through Port 2 (P2.0-P2.7 are connected to DB0-DB7). While the input data for the LCD viewer is removed through Port 1 (P1.0-P1.7 are connected to D0-D7). To control the foot RS and E on the LCD microcontroller use P3.6 and P3.7 foot
The process of data acquisition and data processing can be seen in figure 7. Data taken from P2 calibrated beforehand, after the calibrated data is then converted into ASCII code 0-100 so displayed on the LCD, if not changed then the numbers displayed are 0-255.

IV. TESTING AND ANALYSIS

4.1 Testing of each block
4.1.1 Testing LM35
LM35 temperature sensor is tested by providing a 5V supply and provide indirect heating, while the output voltage directly observed with a voltmeter. From the test data obtained as follows.

Table 2. The test results LM35 sensor

The output voltage temperature
35 ° C 00:35
40 ° C 00:40
45 ° C 00:45
50 ° C 12:51
55 ° C 00:55
60 ° C 0.65
65 ° C 0.71
70 ° C 0.76

From the test results are known voltage sensor output increased by 50mV for every 5 ° C or 10mV / ° C, the sensor is working properly.

4.1.2 Testing the signal conditioning circuit
Signal conditioning circuit testing is done by providing the voltage change at the end of the amplifier input (non-inverting amplifier) ​​and then measure the output to then calculated the level of reinforcement stress.

Table 3. The test result signal conditioner

Av = Vout Vin (Vout / Vin)
0.1 V 0.5 V 5
0.2 V 1V 5
0.3 V 1.5 V 5
0.4 V 2V 5
0.5 V 2.5 V 5
0.6 V 3V 5
0.7 V 2.5 V 5

From the data table is known that the level of strengthening the signal conditioning circuit voltage is 5 times, then the circuit has to work properly.

4.1.3 Testing ADC 0804
Testing is done by giving voltage to the ADC input and record the output of digital data generated through an 8-bit LED display.

Table 4. ADC test results.

Digital data input voltage
0.6 v 23 H
1.2 41 v H
1.8 62 v H
2.6 v H 8D
3.4 v B7 H
4 v DF H
4.2 v EF H
FF v 4.9 H

ADC data test results indicate that these components can work well.


4.1.4 Software Testing
Software testing program involved testing of the temperature data acquisition and calibration of data acquisition of temperature on the LCD display. The process of testing done by looking at the digital data visually displayed on the LED indicator is the data acquired and comparing the results of the temperature display on the LCD.

Table 5. Results of testing temperature display

Digital temperature displays temperature data calculated
25 H 35 ° C 35.294 ° C
43 H 44 ° C 44.117 ° C
63 H 53 ° C 53.823 ° C
8D H 66 ° C 66.470 ° C
B7 H 78 ° C 78.823 ° C
DF H 90 ° C 90.588 ° C
EF H 95 ° C 95.294 ° C
FF H 100 ° C 100 ° C

From the table note that the temperature displayed on the LCD with the temperature of the calculation there is a difference in terms of accuracy, where the temperature is displayed on the LCD is a rounded value without displaying the value behind the comma, while the temperature is calculated as the temperature standard that must be displayed. Removal of the coma is intended to facilitate the process of making the program, but with the consequences of error rates due to the removal of the displayed temperature. Software has to calibrate the digital data and displays the temperature value of a plant, then the software has to work properly.

4.2 Testing the overall system
Testing the overall system is done by placing the sensor LM35 and thermometers in the temperature of the same plant and then compares the temperature is displayed on the LCD appointment to appointment of temperature on the thermometer for 30 minutes.

Table 6. Results of testing system

Display temperature
LCD temperature display thermometer Error
30 ° C 29.7 ° C 0.3 ° C
32 ° C 32 ° C 0 ° C
34 ° C 34 ° C 0 ° C
37 ° C 37.5 ° C 0.5 ° C
40 ° C 40 ° C 0 ° C
45 ° C 45.6 ° C 0.6 ° C
46 ° C 46 ° C 0 ° C
47 ° C 46.7 ° C 0.3 ° C
 error 1.7 ° C

The results showed that the temperature data acquisition system has an average error of 0.2125 ° C, this value is obtained by summing all the error value of each test divided by the number of tests (8 times).

V. CLOSING

5.1.1 Conclusion
From the design and manufacture of temperature acquisition system device can be concluded that - as follows:
1. ADC Test results indicate that for input of 4.9 V digital data has reached FFH, then the designation will result in errors when the temperature where the input voltage 4.9 V displays the temperature has reached 100 ° C.
2. Error average temperature on the appointment of the temperature data acquisition system is 0.2125 ° C.
3. LM35 has a sensor output voltage with an increase of 50 mV for every 5 ° C or 10 mV / ° C, the sensor has a fairly linear increase.

5.2 Suggestions
1. At the output end signal conditioning circuit should be added clipper circuit which serves to limit the ADC input for a maximum of 5V.
2. To simplify the zero setting of the differential amplifier circuit output LM35 should be strengthened so that the first reference voltage reduction is not too small.
3. Reference voltage source deduction should use a zener diode to obtain a stable voltage.
4. To make more precise temperature data view, the calibration program can be made better temperature data.

Temperature data acquisition using microcontroller

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History of Computers

Computers we use today are not necessarily just show up but through a long process of evolution. Happenings emergence of the computer may be viewed in flashback history since the use of Abacus - found in Babylon (Iraq) about 5000 years ago - as a means of manual calculation of the first, both in the scope of the school and among traders, at the time.

At a later period has been widely found in the means of calculating the mechanical kind that is Pascaline invented by Blaine Pascal in 1642, arithometer by Charles Xavier Thomas de Colmar in 1820, Babbage's Folly by Charles Babbage in 1822, and Hollerith by Herman Hollerith in the year 1889.

All are still a machine entirely without electricity. The size and complexity of its structure based on calculations performed the operation level. It was only in 1940, began a new era since the invention of electrical computer electrically computers that implement Boolean algebra.

The development of computer technology which is described below in the top four generations based on the components it uses, ranging from the size of "big" to micro-line also with the complexity of its components.

First Generation
Today is the era giant computers, such as Z3, Colossus, ENIAC, EDVAC, EDSAC, UNIVAC I. Characteristics of computers in this era marked by the size almost as big as the bedroom, using a vacuum tube with a number of very much to store and process the orders or instructions, consuming thousands of watts of electric power, using machine language and can only be used by a person trained.

So, the layman would not be able to use it so that computers of this type has not been commercialized to the general public. Only large corporations, educational institutions and government agencies that use it.


Second Generation
This era began with the use of transistors and diodes as a replacement of vacuum tube that sizenya smaller than its predecessor generation.

Another invention is the use of magnetic core memory that hold data, so much faster in data processing, and machine language has been replaced with assembly language (Fortran and Cobol) that facilitate the operation. Some examples of the computer at this time, the Stretch, LARC, DEC PDP-8, IBM 1401, IBM 7090 and IBM 7094.


Third Generation
A new era of computer communication set foot on the momentum from this. Most large companies implement on-line system using a remote terminal in the use of computers (read: on-line).

This technology must be supported by an increasingly computer performance in terms of both hardware and software usage. New discoveries in the field of hardware acted with the emergence of IC (Integrated Circuit) in computer components.

Because of its advantages in uniting the various components in a single chip so that the computer at the time computers became ever smaller size without degrading the performance of the output, and even further improve its performance.

In the software, programming techniques plural (Multi-Programming) began to be developed so that more and add a collection of various existing programming languages. Cray-1, 90/30 UNIVAC and IBM 360 is a few examples of computers in this generation.


Fourth Generation
Along with the speed of time development of the computer as a tool of data processing has increased rapidly, especially in this generation. The growing speed is inversely proportional to the smaller size, supported by a larger memory capacity. The price is getting cheaper due to its components have been manufactured and sold in mass.

In this period various IC united into a single unit forming a component called the VLSI (Very Large Scale IC). Use of the software more easily and develop into effect on home computers, such as word processing and spreadsheet. Internet network was more extensive that previously only enjoyed by the elite groups now can be used also by ordinary people.

The use of microprocessor is now an absolute no longer used only on computers but has been applied to other electronic products, such as televisions and microwaves. Seeing the development of the computer world a very high rate of growth starting from the beginning to the present generation can we predict how the characteristics of the computer on future generations.

Possibly, the computer will not have to continue to be dictated by the man but he had to do everything yourself. Virtually ability already resembles human intelligence. Such capabilities (Artificial Intelligence or Artificial Intelligence) is now actively investigated by the developed countries like Japan and the United States.

Author

Azhar H. Bakrit

History of Computers

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COMPUTER NETWORK TECHNOLOGY

COMPUTER NETWORK TECHNOLOGY

A. Preliminary
Computer networks is not something new today. Almost in every company there is a computer network to facilitate information flow within the company.

Internet is gaining popularity today is a giant computer network which is a network of computers connected and can interact with each other. This can happen because of the development of network technologies very rapidly, so that within a few years the number of users of computer networks belonging to the Internet doubled.

B. Computer Networking
1. Definition
Computer network is a collection of computers, printers and other equipment are connected. Information and data moves through the wires to allow users of computer networks can exchange documents and data, print on the same printer and share the hardware / software that connects to the network.

Each computer, printer or peripherals that connect denganjaringan called nodes. A computer network can have two, tens, thousands or even millions of nodes. A network typically consists of 2 or more computers that are interconnected among each other, and share resources such as CD-ROM,

Printers, exchange files, or the ability to electronically communicate with each other. Computers that connect those, made possible with the media cables, telephone lines, radio waves, satellite, or infrared rays.

2. Network Types
There are 3 kinds of Networks / Network are:
a. Local Area Network (LAN) / Local Area Network.
A LAN is a network that is limited by a relatively small area, generally bounded by the area like an office environment in a building, or a school, and usually not far from about 1 km square.

Several models of LAN configuration, one computer is usually made in a file server. Which is used to store software (software) that regulate network activity, or as software that can be used by komputerkomputer that is connected to the network.

The computers are connected to the network (network) is usually called a workstation. Workstation capabilities more usually under the file server and have other applications in the hard drive in addition to applications for the network. Most LANs use the media cable for connecting between one computer to another computer.

b. Metropolitan Area Network (MAN) / Metropolitan area network

A MAN, usually covering a larger area than a LAN, for example between regions within a province. In this case the network connecting several small networks into larger areas of environment, for example are: network

Bank where several branches of a bank in a big city is connected between each other. For example, Bank BNI in the entire region or Surabaya Ujung Pandang.

c. Wide Area Network (WAN) / Large Scale area network

Wide Area Networks (WAN) is a network that already use a scope usually means satellite or submarine cable as an example of the whole network BANK BNI in Indonesia or in other countries.

Using the WAN facilities, a bank in Bandung can contact its branch offices in Hong Kong, just a few minutes. WAN usually rather complicated and very complex, using many means to connect between LAN and WAN to the Global Communications such as the Internet.

But somehow between LAN, MAN and WAN are not much different in some respects, only the scope of the area is just a different one among others.

3. Protocol

Protocol is a set of rules that govern communications between computers on a network, the rules include guidelines that apply to the ways or methods of accessing a network, physical topology, the types of cable and data transfer speeds.

Protocols supported are as follows:
1. Ethernet
2. Local Talk
3. Token Ring
4. FDDI
5. ATM


Ethernet
Ethernet protocol is by far the most widely used, the Ethernet access method called CSMA / CD (Carrier Sense Multiple Access / Collision Detection). This is a system where each computer listens to the cable network before sending anything into it.

If the network is clear, the computer will transmit the data, if there is another transmission on the cable, the computer will wait and will try to re-transmission if the network has been clean.

Sometimes, two computers transmit at the same time, when this happens, each computer will be back and will wait a random chance to transmit data back. This method is known to the coalition, and will not affect the speed of transmission on the network.

The Ethernet protocol allows for linear bus, star, or tree. Data can be transmitted over twisted pair cable, coaxial, or fiber optic cable at speeds of 10 Mbps.

COMPUTER NETWORK TECHNOLOGY

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AVR Microcontroller Programming with C

Programming Language C for AVR widely used C language for programming a variety of devices, including microcontrollers. This language is already a high level language, which allows programmers pouring algorithm. To know basic C language can be studied as follows.

1. Coding Structure
# Include <[library1.h]> / / Optional
# Include <[library2.h]> / / Optional
# Define [name1] [value]; / / Optional
# Define [name2] [value]; / / Optional
[Global variables] / / Optional
[Functions] / / Optional
void main (void) / / Main Program
{[Declaration of local variable / constant] [Contents Main Program]}

2. Data type
char: 1 byte (-128 s / d 127)
unsigned char: 1 byte (0 to 255)
int: 2 bytes (-32 768 s / d 32 767)
unsigned int: 2 bytes (0 s / d 65 535)
Long: 4 bytes (-2,147,483,648 s / d 2147483647)
unsigned long: 4 bytes (0 to 4,294,967,295)
float: decimal
array: a collection of the same data type.

3. Declaration of variables and constants
The variable is a data storage memory whose value can be changed.
Writing: [Data type] [name] = [value];
Constant is data storage memory whose value can not be changed.
Writing: const [name] = [value];
Supplement: Global variables / constants that can be accessed throughout the program.
Local variables / constants that can only be accessed by the function of the declaration.

4. Statement
Statement means any operation in programming, should end with [;] or [}]. Statement will not be executed if preceded by a [/ /] for a single line. More than 1 line to use the couple [/ *] and [* /]. Statement is not executed is also called comments / commentary.
Example: temperature = adc/255 * 100; / / example of formula calculation temperature

5. Function Function
is part of a program that can be called by the main program.
 Writing: [type data] [function name] ([type of data input 1], [type of data input 2]) {[statement];}

6. Conditional if else statements and loops
used for the selection condition
if ([requirements]) {[statement1]; [statement2];} else {[statement3]; [statement4];}
for: used for loops with a known amount
for ([initial value]; [requirements]: [the operation value]) {[statement1]; [statement2];}
while loop: used to loop if and flesh, certain eligible
while ([requirements]) {[statement1]; [statement2];}
do while loop: used to loop if and flesh meet certain requirements, but min 1 time
do {[statement1]; [statement2];} while ([requirement])
switch case: used for selection with many conditions
switch ([variable name]) {case [value1]: [statement]; break; case [value2]: [statement]; break;}

7. Operation logic and binary logic
AND: & &
NOT:!
OR: | |
Binary AND: &
OR: |
XOR: ^
Shift right:>>
Shift left: <<
Complement: ~

8. Relational operations (comparisons)
Equal to: ==
Not equal:! =
Bigger:>
Bigger equals:> =
Smaller: <
Smaller equal to: <=

9. Arithmetic operations
+, -, *, /: Add, less, times, for
+ =, -=, *=, / =: Value to the left of the operator on the plus / less / multiply / divide by the value of the right of the operator
%: Remainder for
+ +, -: Plus one (increment), less one (decrement)
Example:
a = 5 * 6 + 2 / 2 -1;
then the value of a is 30 a *= 5;
if the initial value of a is 30, then the value of a = 30x5 = 150. a + = 3;
if the initial value of a is 30, then the value of a = 30 +5 ​​= 33. a + +;
if the initial value of a is 5 then the value of a = a +1 = 6. a -;
if the initial value of a is 5 then the value of a = a-1 = 4.

AVR Microcontroller Programming with C

Posted by science.essence.seven

On 10:17 AM

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