Line Coding Techniques in Matlab

In this article I will start with the basics of MATLAB for writing scripts.I have written this MATLAB scripts for simulating the working of Digital Communication line trainer of Line Coding type Unipolar RZ.I will not delve into detail about the line coding technique as it is pretty basic.

First of all check out the simulation snapshot of the output of the scripts on Figure 1.

As you can see from the screenshot I have set the input data as 11110000 and we can see the corresponding output.

Let us see the data line by line

Let It is required to clear the console area and clear all the variables that were being used in MATLAB Command area.So to achieve that we use these commands.

close all;

This command closes all the active windows previously running.

clc;

clear all;

close all;

It is required to clear the console area and clear all the variables that were being used in MATLAB

Command area. So, to achieve that we use these commands.

 Now we will define a line matrix variable bits of 8-bit length, this is the data variable for showing the input data.You can see the

bits = [1 1 1 1 0 0 0 0 0];

bitrate = 1; % bits per second

 Now we will call the urz  function of matlab for variable bits of 8-bit length,the output of this function is used for plotting the output   

I have attached the code for your reference I hope this helps.Soon I will add more line coding techniques. 

  

Source Code(Contents of unipolar.m)

clc;

clear all;

close all;

%bits=input('Enter bit sequence of 9-bit width : ');

bits = [1 1 1 1 0 0 0 0 0];

bitrate = 1; % bits per second

figure;

subplot(4,1,2);

[t,s] = urz(bits,bitrate);

plot(t,s,'LineWidth',3);

axis([0 t(end) -0.1 1.1])

grid on;

hold on;

title(['Unipolar RZ: [' num2str(bits) ']']);

Embedded Trainer ET-51LS TRAINER

The attached picture is the Development trainer board with in-built programmer compatible with all versions of keil ide.

The training kit provides ideal platform for learning embedded C with actual applications on hardware.

For example:
To learn the working of switch statement ,you can write a program which generates different led patterns based on the input from 4 switches provided.

The kit has different display standards such as full numeric displays,LCD and led that can be used as per requirement.

These kits has been conceptualized keeping in mind requirements of different courses of embedded of several universities and research design.

Complete flexibilty of opearting the kit using a usb port and downloading the program using nxp's flash programming  software ,makes rhe kit user friendly.

The combined material comes with a detailed user manual containing 14experiments covering in details all the different accessories attached such as opto,relay,ir module,keyboard matrix,led matrix, stepper motor controller and more.

Thus kit is a stepping stone for students who wants to make their minor and/or major project for completing their gradute/post graduate courses.

I hope you have liked the review ,please contact me for further details or more.

Abhishek Verma
09868715910

Generating fixed clock using 8051 Microcontroller.

This article is focused for the budding engineers/hobbyists and anyone who wants to start working on 8 bit microcontroller. Al, the programs listing has been compiled on KEIL IDE and downloaded on 89V51RD2 on the Vinytics,Delhi (ET-51LS TRAINER) the picture of the kit is attached. Most of the codes that we will be considering for our learning will require only a CRO/DSO for understanding rest all the accessories required are present on the kit itself like I/O lines on 8 pin connector, keys, LEDs, LCDs, Relay & many more.

In this article we will explain you how to generate a fixed signal (clock) of 50% duty cycle. In some application we require a fixed clock signal for controlling the hardware there are 32 input/output lines on 8051 that can be programmed according to the requirement.

Let us understand the source code attached in the article.

We need to assign a constant to the port for easy understanding and readability, using sbit we can assign a constant to a pin number of port 1. The width of sbit 1, this is bit variable it can only take value of 1/0.

The declaration of pin should be done before the main loop of the source code.

sbit pin = P1^0; // decleare a variable type sbit for P1.0

We have used a long type of variable to assign the delay between the pin signal High & Low. We are declaring a counter for repeating the function C number of times to generate a clock of fixed time 300 ms.

Definitation of Long variable type is

“A signed or unsigned long integer.”

long C;

Delay 1 function is a standalone function that can be called as many times as possible in the source code. For a single call of delay 1 function you will get a delay of 300 ms.

void DELAY1()

{

for(C=0;C<450 o:p="">

}

This is the main source code of the program in this program we are making a super loop using the while statement we are making while (1), this statement makes the while condition always true that means the programs runs itself infinitely. We are making pin high and calling the DELAY1()  sub routine to give the delay of 300 ms and then making the pin  Low as result we get a clock signal of almost equal duty cycle at the port 1 _0 OR pin

main()

{

while(1)

{

            pin=1; // clear port

  DELAY1();

            pin=0; // clear port

  DELAY1();

            }

           

}

/*program for fixed 33.33hz*/

#include // include 8051 register file

sbit pin = P1^0; // decleare a variable type sbit for P1.0

long C;

void DELAY1();

void DELAY1()

{

for(C=0;C<450 o:p="">

}

main()

{

while(1)

{

                        pin=1; // clear port

  DELAY1();

            pin=0; // clear port

  DELAY1();

            }

           

}

NOTE: I will add the video tutorial of working with ET-51LS on my youtube channel for this program in the coming week.

Please visit the video tutorial of Microprocessor kits on my youtube page

https://youtu.be/jjFr2Yxm3uU

Designing a Three Phase Voltage Source Inverter

Lets discuss about designing a Voltage Source Inverter using IGBT

First let me start by explaining the working concept for voltage source inverter.

Three Phase Voltage source inverters are used where it is required to generate and control a three phase power from a single phase source.For example in remote areas where power is being generated from solar primarily.The three phase power offers more flexibility and efficiency in all applications like watwr pumping ,irrigation etc.

So let us start designing a vsi.

First make a bridge rectifier ,it can be three phase rectifier or single phase rectifier depending upon your requirement then make sure the voltage is more than 290V DC.Then put a series lamp preferrably 200w in series.
Use a 6-IGBT bridge and apply the dc to both the sides of the inverter by shorting one end of the IGBTs.

Now generate the PWM from microcontroller and trigger the igbt by firing pair in a sequence.You will observe three phase at output.It can be used to run motors and all different loads.

I hope this blog will help to get a good understanding of the inverter.

My plan is to launch my own Three Phase VSI by tomorrow ,wish me luck.Watch my youtube videos for more info.

Designing a AC Motor Controller

In this blog i will be talking about the iasues related with designing a Single Phase Induction Motor Controller for a 220v AC Motor.

Let me start by stating that designing with microcontroller is bkth fun and effective.

So let me give you some headsup on the flowchart of the program.

1. Keep your hardware ready,work out the circuit on paper and understand the limits of your circuit i.e. voltage range and current range depending up9n the size of motor you are going to use.

2. Test out your circuit by always keeping a lamp load in series with your load,it helps in case of short circuit.

3. Now your aim is to replace your working circuit firing mechanism with the pulse width modulated waveform from your microcontroller.

4. Most important thing is to read the datasheet of the power electronic device you are using to understand the minimum pulse width required to trigger the device i.e 20ns

5. Always generate the pwm with reference to the interrupt signal activated by the external 50hz zero crossing detector output.

Today I have completed my panel for the same topic discussed above and attached the picture of it in the blog.Dont forget to see my youtube videos.

Have a great day designing new projects with these inputs.

Controlling a induction motor using a single phase induction motor controller

Controlling a induction motor using a single phase induction motor controller 


There are two ways of controlling the speed of a 230v induction motor

1. By varying the ac voltage 
2. By varying the line frequency 

In this method of controlling the ac motor ,we will be using a TRIAC which is fired by an UJT.

As the name suggests the TRIAC can conduct in both the directions controlled by a gate pulse.

The gate pulse is varied by a Uni Junction Transistor which has a property to generate pwm.The advantage of triggering with UJT is that it offers a regular off timw for the TRIAC to cool down and as a result the requirement of heat sink is reduced.

The firing of UJT is generated by varying the dc voltage at the base.But the convenience of easy firing scheme has a drwaback of low range of operation i.e. from ac 20v to 190v.

I hope you had a great time reading this article join me tomorrow with more information. To see the working of Electric Drives AC and DC.Visit my youtube channel Fully Controlled Bridge.Rgectifier Trainer

DC MOSFET CHOPPER -CONTROL DC SHUNT MOTOR 220V/1500RPM

Tips and Tricks on Interfacing LCD with Microcontroller

CONNECTION DIAGRAM 

Today I will explain you  creating a Interface on any LCD with a microcontroller  like 8051,ARM .

Many development boards have inbuilt hardware lines with the io's of mixrocontroller but for a novice i would suggest doing it manually.

1. Always connect the data lines of the LCD to the port which has all the IO Lines free

2. You can always mix the control lines of LCD with the data input lines.

3. Make sure you always read a switch on the interrupt,it allows the program to run smoothly.

4. Always study your LCD Datasheet's timing diagram before working on the Interfacing.

5. Always keep a time delay(in millisec) that works best with your LCD to refresh the data(refer to your LCD's Datasheet for exact delay).

6. Always keep a CRO/DSO handy while working with LCD, if the screen does not refresh itself after you reset the controller,then there is a problem with your EN signal.

7. If LCD is getting CLEARED,but the data is not displaying then there is a problem with the delay in LCD WRITE routine.Use the CRO probe on the data lines ,you should be able to see a clock on the data lines if the LCD is recieving the data otherwise check your cnnections

I hace uploaded a circuit for LCD Interfacing which has worked for me for interfacing with 89C51RD2 .

I will be working on creating PWM for controlling a Single Phase Induction Motor in coming days and will upload tips and tricks for the same.

Have a great time and mail me all your queries in the comments section.For more panels and instruments used in Engineering Labs refer to my youtube videos






Digital Communication Trainer - The youtube helps you to learn the concept of PAM ,PPM and PWM experiments done on a  Vinytics Communcation Lab Instruments Kit

See the suggested video columns for training kits that are used in your own college Labs and master them.