Electronics Circuits and Projects for Engineering Students and beginners

LCD Control using UART Serial Port

2010-07-13T12:30:00.000+05:30

Introduction:

When you write an LCD Program to write your name or any text, you can only display the same text at all times. If you have to change the text, you have to change the code, recompile it again and then reprogram it. Instead of doing all this, you can just connect your circuit to serial port of computer and change the text on LCD instantly using the hyperterminal of the PC. You can just type any text in the hyperterminal and press ENTER key. The text will be displayed on the LCD instantly. You can customize the display by changing the pattern.

AVR GCC CODE
/*
Purpose:It will take input from the terminal and writes that on LCD

Hardware: 
ATmega8 @ 16MHz 
PC Software : Hyper terminal @ 19200 baud 
No Parity,1 Stop Bit, 
Flow Control = NONE 
*/ 
#include  
#include  
#include   
#include 
#include "uart.h" 
#include "lcd.h" 
 
static int uart_putchar(char c, FILE *stream);
static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
 
static int uart_putchar(char c, FILE *stream)
{
if (c == '\n')
uart_putchar('\r', stream);
loop_until_bit_is_set(UCSRA, UDRE);
UDR = c;
return 0;
}
 
int main()
{
stdout = &mystdout;
   //Initialize the LCD Module. 
   LCDInit(LS_BLINK|LS_ULINE);
   LCDClear();
   //USART Initialisation 19200bps @ 16MHz crystal

   USARTInit(51);char str[20],data;int i=0;while(1){printf("\n PLEASE ENTER THE STRING : ");for(i=0;;i++)   {   data = USARTReadChar();

//saving the given string
   USARTWriteChar(data);
   str[i]= data;
   if((str[i]=='\n') ||( str[i]=='\r'))
   {
   str[i]='\0';
   break;
   }
   }
LCDClear();
LCDWriteString(str);

//displaying the saved stringprintf("\n Finished \n");_delay_ms(1000);}}

Implementation:

Open the hyperterminal in your computer. Set the settings as per the code. Then reset your microcontroller. You will see "enter the string : ". Enter the text and press ENTER key. You will get "Finished". You will see the text you entered on the display.

Downloads:
Files related to this project. Click here to download

NEXT VERSION:
The text will display only when you enter the text from terminal. I am developing this code for new options. In the later version of this project, the entered text is saved in the EEPROM and if you change the code directly from the terminal.
I will be updating this post regularly, so subscribe to my blog newsletter(top right of this page) for updated information. If you have any doubts, post you comments here or mail me @ arifuddin2007@gmail.com Arifuddin Sheik

Serial COM port using ATmega8 (AVR Dude Hack)

2010-07-13T11:44:00.001+05:30

Introduction:

Many times, I have written code for UART communication and when it came to testing, my laptop does not have a serial port. I bought a USB to serial port converter but it didnt worked. I felt frustated and finally thought of buying a Serial to Com port module in an electronics hobby store. After seeing that I got the idea of making one myself. I have 2 USB AVR Programmers with me. I tried different circuits but they didnt worked for Windows 7 because of driver problems. I googled for the circuit and finally came to know that the circuit of USB Programmer and USB to Serial port are both same. I just have to connect some wires in the programmer and change the firm ware of the programmer and it became USB to Serial Converter! Voila! My laptop has a serial port now!

There are other methods in internet, but you can only them in old PC's of with Windows 98 or XP. You will find support for high end operating systems like Windows 7. This circuit is tested and it is working 100%. I started using COM port for all my projects because you can give different inputs and debugging became even more simple using serial port.

Click here : http://www.recursion.jp/avrcdc/cdc-232.html

In the above link you will find the details of the circuit. You can build the circuit using ATTiny45 or ATTiny2313 or ATmega8. But the baud rate speeds will vary depeding upon the device you use.

Circuit Diagram:

Circuit Building:

First build the whole circuit using any of the 3 MCU's. You will find the firmwares in the website. Choose CDC32 from here..

http://www.recursion.jp/avrcdc/download.html

Flash the microcontroller using the firmware. You will have seperate firmwares for different MCU. After that connect the circuit to the USB port. The PC will not recognise your driver. Download the driver depending upon your operating system. The best part in this method is that it supports all operating systems including Windows 7. Install the driver manually in device manager options. For checking the working of circuit, just connect Tx and Rx pins with a wire. Open the terminal and type something, you will see the same thing on the screen.

My USB to Serial Converter:
I have built this and connected to my development board. Previously it is a programmer, now it became USB to Serial port to my laptop. I am going to build this using ATTiny45 once I get the chip. But the maximum baud rate with ATTiny45 is only 4800bps as per the circuit. I will post those pics once I finish building the circuit. So keep waiting for my updates.

I have tested this circuit and it is 100% working. You you have any problems building this circuit or with firmare or drivers, post your problems, I will surely help you out.
Click here for sample project after building this circuit.

I will be updating this post regularly, so subscribe to my blog newsletter(top right of this page) for updated information. If you have any doubts, post you comments here or mail me @ arifuddin2007@gmail.com

Arifuddin Sheik

Remote Controlled Home Appliances project using ATmega8

2010-07-10T14:32:00.001+05:30

Hi everyone! First of all I would like to thank Avinash Gupta for writing all the valuable tutorials and libraries for AVR Microcontrollers and helping people like me to build projects and learn new things. I am dedicating this post to him!

Note that I am not the owner of all the libraries used in this project. I made this project using libraries and tutorials from www.extremeelectronics.co.in. The ownership of libraries lies with them. I am publishing this post with their permission.

You can learn many things regarding AVR MCU here www.extremeelectronics.co.in.

For Excellent AVR Tutorials click here.

Introduction:Using remote keys from 1 to 4, you can control 4 appliances. You can easily extend this number to as many you wish. For example, if you press key_1 on your remote, fan will turn ON. If you press the same key again, fan will turn OFF i.e each time you press a key configured for an appliance, the condition will toggle. I have programmed the MCU such that all devices will turn OFF on pressing power button(RED COLOR on top of your remote). You can also choose combinations like turning all fans OFF at a time, etc. With little tweaking, you can change the program yourself! The status of the appliances is shown in an LCD. You can ignore this feature if you dont want LCD. I used LCD for developing the code.

I main advantage in this project is that the appliance status is stored here using internal ATmega8 EEPROM. So, whenever mains power goes off and comes again, the appliance will be in the same state in which it is before. Suppose if power goes off during night. The fan will be off. When power is back, the fan will be automatically turned on again. You dont have to search for remote again!

Another advantage using this circuit is that you dont have to use your TV Remote. You can use any DVD remote. So, chances for interference are very less. Normally when you use TV Remotes, your TV channel will also change with appliance. Personally I faced this problem in my old project. Thanks to Avinash for creating wonderful libraries for using DVD Remote.

Circuit Diagram :

Circuit Explanation :

The project is running off using internal oscillator with 8MHz frequency. So becarefull with fuse bit settings.

Fuse bits :

Int. 8 MHz d9 e4

We are using TSOP1738 Infrared Receiver IC here to get the DVD Remote signals. The output from TSOP Sensor is connected to INT0 (pin PD2). The MCU receives the signals and appropriate action is taken (appliance switching). After switching, the status of device is stored in EEPROM. Then the status is displayed in LCD.

The commands for keys may vary from one remote to another remote. So, before using the remote, check the command values for keys and update them in "rckys.h" file. Otherwise the appliance will not switch. Use the second tutorial for getting the command codes.

To learn about IR Remote decoding, see this tutorials

Tutorial - 1

Tutorial - 2

To use LCD in your projects, see this tutorial. After reading this, you wont find hard to interface LCD in your project. I started using LCD in every project because you will get visual information directly regarding what is happening and program flow. It will be also useful during debugging process which you cant do using software tools. click the below link for LCD tutorial.

LCD Tutorial

LCD Connection for the project :

PIN Configurations:

The lcd modules has 16 PINs for interfacing. The details are given below.

1 VSS (GND Supply)
2 VCC (+5V)
3 VEE (Contrast Adjust)	Connect to gnd for normal contrast
4 RS	PB2
5 R/W	PB0
6 E	PD7
7 DB0	Not Connected
8 DB1	Not Connected
9 DB2	Not Connected
10 DB3	Not Connected
11 DB4	PD3
12 DB5	PD4
13 DB6	PD5
14 DB7	PD6
15 LED+	Vcc
16 LED-	Gnd

Outputs are connected to PORTC from PC0 to PC3. You can change this connection according to your wish by changing the code. The pins PC0 to PC3 are connected to IC ULN2803. This is a high voltage high current buffer. Click here to know how to use the buffer for connecting relays.

Connecting relays

Internal EEPROM is used for saving the appliance status. I searched internet for using internal EEPROM but didnt find useful information. So, I went back to datasheet of ATmega8 and I found the program there! I made the EEPROM library in my project using the datasheet. You will know about EEPROM more in datasheet. You will know the importance of datasheet once you start using it for programming the MCU.

search for "eeprom_read" to understand the eeprom read operation. search for "eeprom_write" in datasheet to understand the eeprom write operation.I created the libraries using those functions only. For understanding code and C tips, click the link below for tutorial in extremeelectronics.co.in written by Avinash Gupta.

C Programming Tips - Embedded Development

AVR GCC CODE :

#include

#include "lcd.h"

#include "remote.h"

#include "rckeys.h"

#include "eeprom.h"

uint8_t app_1,app_2,app_3,app_4,cmd=0;

int main()

{

DDRC|=((1<<<<

//Give Some Time for other hardware to start

_delay_loop_2(0);

LCDInit(LS_BLINK);//Initialize the LCD Subsystem

LCDClear();

InitRemote();//Initialize the Remote Subsystem

/*EEPROM bits have to set to either FF or 00. In default they will be set to FF. But its better to check them using Extreme electronics USB avr burning software.

If the values are other than those, set them to 00 or FF.

00 - OFF

ff - ON

I have written the EEPROM routines using atmega8 datasheet. Refer EEPROM section in datasheet for more information regarding reading and writing of operation in EEPROM.

//Reading from internal EEPROM

app_1 = EEPROM_read(0);

app_2 = EEPROM_read(1);

app_3 = EEPROM_read(2);

app_4 = EEPROM_read(3);

while(1)

{

switch(cmd)

{

case RC_1:

app_1=~app_1;

//toggling the state of appliance

if(app_1==0)

PORTC|=(1<

else

PORTC&=(~(1< //Turn On the appliance_1

EEPROM_write(0,app_1);

//saving the state of appliance

break;

case RC_2:

app_2=~app_2;

//toggling the state of appliance

if(app_2==0)

PORTC|=(1<

else

PORTC&=(~(1<

//Turn On the appliance_2

EEPROM_write(1,app_2);

//saving the state of appliance

break;

case RC_3:

app_3=~app_3;

//toggling the state of appliance

if(app_3==0)

PORTC|=(1<

else

PORTC&=(~(1<

//Turn On the appliance_3

EEPROM_write(2,app_3);

//saving the state of appliance

break;

case RC_4:

app_4=~app_4;

//toggling the state of appliance

if(app_4==0)

PORTC|=(1<

else

PORTC&=(~(1<

//Turn On the appliance_4

EEPROM_write(3,app_4);

//saving the state of appliance

break;

case RC_POWER:

//turn off all the appliances

app_1=0;

app_2=0;

app_3=0;

app_4=0;

EEPROM_write(0,app_1);

EEPROM_write(1,app_2);

EEPROM_write(2,app_3);

EEPROM_write(3,app_4);

break;

}

if(app_1==0)

{LCDWriteStringXY(1,0,"A1-OFF");}

else

{LCDWriteStringXY(1,0,"A1-ON ");}

if(app_2==0)

{LCDWriteStringXY(9,0,"A2-OFF");}

else

{LCDWriteStringXY(9,0,"A2-ON ");}

if(app_3==0)

{LCDWriteStringXY(1,1,"A3-OFF");}

else

{LCDWriteStringXY(1,1,"A3-ON ");}

if(app_4==0)

{LCDWriteStringXY(9,1,"A4-OFF");}

else

{LCDWriteStringXY(9,1,"A4-ON ");}

uint8_t cmd; //dont cut and paste on the top

cmd=GetRemoteCmd(1);

/*Get Remote Command. Command is taken in last because the

the past device status has to be recovered first!

}

Downloads :

Click here to get the project files ( includes AVR Studio Project files and circuit diagram)

Implementation :

I Implemented this project on XboardMini from extremeelectronics. I am posting images of the project. I am currently improving the code for fan speed control and Room light control for the same project. Very soon, I will build the project on a demo board and will post those photos. I will be updating this post regularly, so subscribe to my blog newsletter for updated information.

Wondered how the XBoardMini is working with out power adopter? In the last photo, can you a see a red wire connecting two terminals and the ISP connector with black tape wounded around it? Yes! the development board is running from USB power supply. If you also want to power your development boards directly from your USB, view this post.

Modifying AVR Development board and Programmer

I will be updating this post regularly, so subscribe to my blog newsletter(top right of this page) for updated information. If you have any doubts, post you comments here or mail me @ arifuddin2007@gmail.comArifuddin Sheik

Modifying AVR Development Board and Programmer

2010-07-07T14:55:00.001+05:30

Programmer and Development Board from Extremeelectronics:

Look at the below picture. The programmer I am using is bought from another manufacturer, not from extremeelectronics. It is an USB Porgrammer. You can get it from any leading electronics hobby electronics store. My programmer is not pin compatible with XboardMini which I brought from extremeelectronics. I modified the ISP connector for connecting the USB programmer with the board. The XboardMini does not has Vcc connection in its ISP connector. My programmer has Vcc connection in its ISP connection. 10th pin is free (not connected) in the Xboardmini ISP circuit. I modified my cable such that 9th pin gets Vcc from USB programmer.

The red wire I connected goes from 10th pin to one of its Vcc node. In this way, the board directly gets Vcc from USB power supply. You dont have to use 9V adaptor for programming and powering the board.

I dont know whether the usb programmer from extremeelectronics is having Vcc connection in its ISP Port. Just find an empty pin in the ISP connector in programmer and Development board. Connect that pin to Vcc of the USB port. Just do the same thing in the development board also. Connect the Vcc pin of ISP port to Vcc rail in the board. using this setup, I am able to carry the development board and programmer in my laptop. I dont have to carry a 9v adaptor as finding power sources is not so easy for me as I am always in move. I am happy with my Acer Mini as I am getting a backup of 7hrs! Thanks to Intel for creating such low power processors!

ATMEGA8 Project Demo Board from NSK Electronics:

The board below is an ATmega8 project demo board. I also had same problem of connecting the board to power supply for programming and running the board. The programmer is pin compatible with the board but the demo board has no Vcc connection in the ISP port. I found the Vcc pin in the ISP port and connected to 5v terminals of the demo board. So, i dont have to use adaptor again!
Even I test the peripherals using the Vcc and Gnd ports from demo boards only!

This is a ATmega16/32 development board. It also has the same problem. I did the same thing to this board also. This board has 4 LEDs for code verification. The idea of using PORTC in "remote control project using Atmega8" came from this only. I checked the status using these LEDs!

LCD Connections :

Look at the below figure. When ever it comes to LCD, you have to take out a small PCB and prepare it for interfacing. I know it is a tedious job. I had modified the LCD module like this. With this module, you can directly connect the LCD to your demo boards as shown in the next figure. It is very easy to use and portable.

keep watching my blog for more updates. I will be updating all the information I collected and my projects which I did from 2 years. Subscribe to my newsletter to get email notifications.

If you have any doubts, post you comments here or mail me @ arifuddin2007@gmail.comArifuddin Sheik

Cell Phone Controlled Home Appliance circuit

2010-05-02T16:47:00.007+05:30

Circuit Description:

Ever Imagined controlling your home appliances using your cell phone. You can find a lot of circuits for this application. But they make use of Telephone. I modified the circuit and redesigned it to make it compatible with normal cell phone headphone. Just connect the your phone headphone jack to the phone and the connections to the circuit as shown in the circuit. The relays are connected using the resistor and transistor. Use ULN2803 to reduce the circuit size and increase the performance. The connections from the output of flip-flops has to be given to the inputs of the buffer and relays has to be connected to the buffer.

Normally the tip of the headset is connected to the circuit to the 0.1uF capacitor as shown in the circuit diagram. The ground pin of headphone is connected to the ground of the circuit.

Circuit Diagram:

Operation:

When you press keys in your Phone, the other person will hear some tones with respect to keys pressed. This tones are based on the DTMF technology. Data is transmitted in terms of pair of tones. The receiver detects the valid pair and gives the appropriate BCD code as the output of the DTMF decoder IC.

The output of the DTMF IC is given to the 4x16 decoder IC. We have 12 signals possible because we have 12 keys (including * and #) in mobile keypad. The decoder are outputs are then given to D flip-flops. The outputs toggle whenever a key is pressed.

In DTMF there are 16 distinct tones. Each tone is the sum of two frequencies: one from a low and one from a high frequency group. There are four different frequencies in each group.
Your phone only uses 12 of the possible 16 tones. If you look at your phone, there are only 4 rows (R1, R2, R3 and R4) and 3 columns (C1, C2 and C3). The rows and columns select frequencies from the low and high frequency group respectively. The exact value of the frequencies are listed in Table 3 below:

TABLE 3: DTMF Row/Column Frequencies
LOW-FREQUENCIES
ROW #	FREQUENCY (HZ)
R1: ROW 0	697
R2: ROW 1	770
R3: ROW 2	852
R4: ROW 3	941
HIGH-FREQUENCIES
COL #	FREQUENCY (HZ)
C1: COL 0	1209
C2: COL 1	1336
C3: COL 2	1477
C4: COL 3	1633
C4 not used in phones

Thus to decipher what tone frequency is associated with a particular key, look at your phone again. Each key is specified by its row and column locations. For example the "2" key is row 0 (R1) and column 1 (C2). Thus using the above table, "2" has a frequency of 770 + 1336 = 2106 Hz The "9" is row 2 (R3) and column 2 (C3) and has a frequency of 852 + 1477 = 2329 Hz.
The following graph is a captured screen from an oscilloscope. It is a plot of the tone frequency for the "1" key:

You can see that the DTMF generated signal is very distinct and clear. The horizontal axis is in samples. The frequency of the tone is about 1900 Hz - close to the 1906 Hz predicted by Table 3 (697+1209).

If you have any doubts or problems connecting the headphone to the circuit, post you comments here or mail me @ arifuddin2007@gmail.com

Arifuddin Sheik

Circuit for controlling 8 appliances using TV Remote

2010-05-02T12:39:00.001+05:30

IR decoder Circuit:

The IR circuit can be used to switch devices using TV Remote. Normal circuits can switch only one device. But using this circuit, different devices can be controlled using same remote with different switches. In this circuit, we interfaced 8 devices. These devices are switched using remote keypad -1 to 8. AT89S52 microcontroller is used to control the inputs and outputs. TSOP 1738 (infrared receiver) is used to receive the infrared signals from TV Remote. ULN2803 (High voltage, high current) buffer is used to drive relays.

Circuit Diagram:

IR Decode Circuit

RC-5 Protocol: To understand the operation the details of RC-5 Protocol has to be studied.

Buy an 8 channel relay board for easy installation as the board will contain relay mate connectors for connecting the switch board wires. Post your doubts if you have any...

RF Controlled Home Appliance Circuit

2010-05-02T12:01:00.001+05:30

Circuit Description:

Transmitter

This circuit consists of Transmitter and Receiver section. The circuit can be used to control home appliances within a range of 30 meters. In open area, you can expect a range of 100 meters. The circuit comprises HT12 Encoder and Decode IC's. HT12 Encoder is used in the transmitter (remote) circuit where as HT12E is used in receiver circuit. The Encode IC encodes the 4 bits of data and transmit it serially to to RF Transmitter module. These 433Mhz transmitter and receiver modules operate using ASK Modulation.

Receiver:

For complete information regarding ASK Modulation, click here

The converse operation happens in the receiver section. The serial information is given to the decode section and the ICHT12D decodes the 4 bit data and gives across the data pins. The devices are then connected using the ULN2003 high voltage high current buffer.

These are some of the images of my own remote. You can design something like this. I had modified it and soldered with in the size of 9V battery. I will post that photos also very soon.

For entire range of photos of this project, click here ( you should be an orkut user to access them)

goto photos : RF circuit photos

Computer Controlled Home Appliance circuit

2010-05-02T11:23:00.002+05:30

you can control your home appliances very easily using this circuit. Use ULN2803 for controlling 8 devices. just connect pin-1 of parallel port connector to pin-1 of ULN2803. You will have 8 channels in ULN2803 and 9th pin is ground for that IC.

To Download the Parallel Port Controller software to switch the devices Click here.

TV Remote controlled home appliance circuit

2010-05-02T09:58:00.001+05:30

This is one of the popular EFY circuit. i build this one very easily. The circuit consists of very less components and simple in design.

Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance turn on/off from a TV, VCD or DVD remote control. The circuit cane activated from up to 10 metres. The 38kHz infrared (IR) rays generated by the remote control are received by IR receiver module TSOP1738 of the circuit. Pin 1 of TSOP1738 is connected to ground, pin 2 is connected to the power supply through resistor R5 and the output is taken from pin 3. The output signal is amplified by transistor T1 (BC558).
The amplified signal is fed to clock pin 14 of decade counter IC CD4017 (IC1). Pin 8 of IC1 is grounded, pin 16 is connected to Vcc and pin 3 is connected to LED1 (red), which glows to indicate that the appliance is ‘off.’ The output of IC1 is taken from its pin 2. LED2 (green) connected to pin 2 is used to indicate the ‘on’ state of the appliance. Transistor T2 (BC548) connected to pin 2 of IC1 drives relay RL1. Diode 1N4007 (D1) acts as a freewheeling diode. The appliance to be controlled is connected between the pole of the relay and neutral terminal of mains. It gets connected to live terminal of AC mains via normally opened (N/O) contact when the relay energises. you can use any NPN transistor inplace of BC548. You can also use SL100 or any NPN transistor lying around you.

The delay depends on the C1 capacitor. Using higher value capacitor will create more delay and using less value capacitor will switch the circuit more than 2 times when you press a remote. Analyse the circuit by placing the 10uf capacitor in place of C1 (100uf).

personally I faced many problems using relay for the first time. A detailed explanation regarding relays can be found here..

If you face any problems soldering this circuit, post here. This is simple than the previous version of this type of this circuit. The

TV Remote controlled home appliance circuit with 555 timer

2010-05-02T09:39:00.001+05:30

This is my first post and and this is the first circuit i made. There are many types of circuits for controlling home appliances using TV Remote. In fact I had confused a lot when I am a beginner searching for this type of circuits. The circuit here 555 timer IC to avoid fast switching. you can only switch the circuit after 3 seconds.

IR remote sensor IC TSOP 1738 is used for recieving the signal. Normally when no signal is falling on IC3 the output of it will be high.This makes Q1 OFF.When a signal of 38 KHz from the TV remote falls on the IC3 its output goes low.This makes Q1 conduct and a negative pulse is obtained at pin 2 of IC 1 NE 555.Due to this IC1 wired as a monostable multivibrator produces a 4 Sec long high signal at its out put.

This high out put is the clock for IC 2 which is wired as a Flipflop and of , its two outputs pin 3 goes low and pin 2 goes high.The high output at pin 2 is amplified to drive the relay .For the next signal the outputs of IC2 toggles state. Result, we get a relay toggling on each press on the remote.Any appliance connected to this circuit can be switched ON or OFF.

The 555 timer is used to create a 3 sec delay for avoiding fast switching. You can also achieve this by using a high value capacitor across TSOP sensor. Click here to go view that circuit.