uRaNGaTaNG » Arduino & Co.

Arduino: Fade and pulse a LED with just using a DigitalPort

tobi — Sun, 17 May 2009 13:40:45 +0000

This is a nice experiment I did to fade and pulse a LED by just using a digital port. Digital? On/Off, 1/0 – how can this work? Well it does, check this out:

Click here to view the embedded video.

The key is, I’m switching the LED on & off very fast which appears the human eye as it’s on all the time (similar to a LED Matrix). Now, I change the time period between switching the LED on and off. Is the off period time longer, the LED lights low, is the off period time short, the LED lights high. Fading the period time, makes the LED pulse… nice!

Check this (still quite ugly) code:

int ledPin = 13;      // LED connected to digital pin 13
int value = LOW;    // previous value of the LED
long cnt = 0;         // will store last time LED was updated
long low = 0;         // interval at which to blink (milliseconds)
long high = 1000; // interval at which to blink (milliseconds)
int op = 3;
long a = 0;

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
}

void loop()
{
  a += op;
  blinkl( a+30, 10 );
  if( a > 200 || a < 0 ) op *= -1;
}

void blinkl(long low, long high )
{
  int c = 5;
  while ( c > 0 ) {
   blink( low, high );
   c-=1;
 }
}

void blink( long low, long high )
{
  long period = 4000;
  long pt = period * high / (low + high );
  int value = LOW;
  digitalWrite(ledPin, value);

  while( period > 0 ) {
    if (period < pt && value == LOW ) {
      value = HIGH;
      digitalWrite(ledPin, value);
    }
    period -= 1;
  }
}

Ruby Serialport and Arduino – that’s easy!

tobi — Thu, 14 May 2009 19:59:34 +0000

Yeah, just controlled my Arduino via the ruby irb console using ruby serialport. Damn easy! (well at least on a Mac, running OS 10.5.7) Hehe, soon more to come…

More to get you started with Arduino and Ruby:
http://www.arduino.cc/playground/Interfacing/Ruby

Second try: 2×5 LED Matrix Arduino controlled

tobi — Tue, 28 Apr 2009 10:14:04 +0000

This time a more sophisticated example. I started to develop an LED Matrix controller and editor in Processing (like every does his first steps on arduino, I think).
By now, you can create a sequence by selecting the LEDs to light up and move over to the next frame. Finished, run it on the Arduino and control the speed – a nice and quick ~~toy~~ way to create any light patterns you can think of easily.

Click here to view the embedded video.

More examples and source code soon to come…

My first Arduion test: 10 LEDs running light

tobi — Fri, 24 Apr 2009 19:05:19 +0000

Check this out:

Click here to view the embedded video.

That my first proper Arduino test, controlling a 10 LED running light. I attached a small button via interrupt as well to start & stop the light. More to come soon, stay tuned!

Here the (very,very ugly) source code:

int ledPin = 3;      // First LED connected to digital pin 13
volatile int stop = LOW;

void setup()
{
  Serial.begin(38400);
  for( int i = 0; i < 10; i++) {
     pinMode(ledPin + i, OUTPUT);
  }
   attachInterrupt(0, stopit, RISING);    //Button attached to Pin 2
}

int i = 0;
void loop()
{
    for( i = 0; i < 7 && !stop; i++) {
      blink(ledPin + i);
    }
    for( i; i >= 1 && !stop; i--) {
      blink(ledPin + i);
    }
    for( i = 0; i < 10 && !stop; i++) {
      blink(ledPin + i);
    }
    for( i; i >= 3 && !stop; i--) {
      blink(ledPin + i);
    }
    for( i; i < 10 && !stop; i++) {
      blink(ledPin + i);
    }
    for( i = 9; i >= 1 && !stop; i--) {
      blink(ledPin + i);
    }
}

void stopit()
{
  delayMicroseconds(1000);
  stop = !stop;
}

void blink( int pin ) {
      digitalWrite(pin, HIGH);
      delay(120 - abs( pin - 8 ) * 20);
      digitalWrite(pin, LOW);
}

Arduion has arrived

admin — Fri, 17 Apr 2009 10:09:44 +0000

Here it is! Yeah, finally my Arduino (ordered at Watterott) has been delivered. Can’t wait to get my hands on it. Stay tuned for future reports!

All about this great ‘toy’ here: www.arduino.cc