DIY IR Proximity Detector

January 25, 2010 by admin · 6 Comments
Filed under: electronics 

Hi friends…

This sensor module called proximity detector, widely used in robotics and other electronic proximity detection purposes. It is very simple to make and use.There is no effect of ambient light on the operation of sensor as a 38KHZ modulated IR pulses are used.

555 Timer is used to generate frequency of 38 KHz and very familiar IR detector module TSOP 1738 is used to detect the 38KHz IR pulses.

Circuit Diagram – Transmitter

38Khzastable

Circuit Diagram Receiver -

tsop_rx

Suggested Assembly -

sam

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Controlling R_G_B Led using Microcontroller

November 2, 2009 by admin · 2 Comments
Filed under: Microcontrollers, electronics 

Hi…

Here is another experiment to share. An RGB led is a electroluminescent device capable of creating any color by some combination of Red, Green and Blue LED. Actually it is a LED with 3 led’s (red, green & blue) inside one package.

RGB led has 4 Legs. The one i have has one leg for Vcc (Positive Supply) and other three terminals corresponding to R, G and B values.

Different color patterns can be generated by controlled PWM Pulses on respective terminals.

RGB-4pin1

From left to right in above picture -> 1. RED  2. Vcc   3. GREEN  4. BLUE

Now lets move onto the main part that is How to control using Microcontroller. I am going to use ATmega8l from AVR family for demo. You can use any controller the concept will remian the same.

rgb_led

And here is the code that generates almost all combination’s of R G B using PWM over three pins of MEga8.

PORTC_0 —-Controlling  RED

PORTC_1 —-Controlling GREEN

PORTC_2 —-Controlling BLUE

#include<avr/io.h>
#include<util/delay.h>
#include<compat/deprecated.h>
#include<avr/interrupt.h>
unsigned char r=255,g=0,b=0;

ISR(TIMER0_OVF_vect)
{
  sbi(PORTC,0);
  _delay_ms(255-r);
  cbi(PORTC,0);
  _delay_ms(r); 

   sbi(PORTC,1);
  _delay_ms(255-g);
  cbi(PORTC,1);
  _delay_ms(g);

  sbi(PORTC,2);
  _delay_ms(255-b);
  cbi(PORTC,2);
  _delay_ms(b);   

}

int main(void)
{
  DDRC=0xFF;   // PORTC as output
  PORTC=0xFF;  // Initially all leds off no color
  TCCR0=0x01;  // No prescaling of timer clock
  TIMSK=0x01;  // Timer Overflow interrupt enable
  TCNT0=0;
  sei();   // Global interrupt enable
  while(1==1)    // Infinite loop
  {
    if(r==255 && g==0 && b==0)
    {
        r=r-1;g=g+1;
        if(g==255 && b==0 && r==0)
        {
          g=g-1; b=b+1;
           if(b==255 && r==0 && g==0)
           {
              b=b-1;r=r+1;
           }
         }
    }
  }
  return (0);
}

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