adding random to sketch

Projects Programming
1

hi all i have got this sketch but i want it to fade at random but i dont know where to put the random bit
any help would be appreciated i have the mega

/*
  Mega analogWrite() test
 	
  This sketch fades LEDs up and down one at a time on digital pins 2 through 13.  
  This sketch was written for the Arduino Mega, and will not work on previous boards.
 	
  The circuit:
  * LEDs attached from pins 2 through 13 to ground.

  created 8 Feb 2009
  by Tom Igoe
  
  This example code is in the public domain.
  
 */
// These constants won't change.  They're used to give names
// to the pins used:
const int lowestPin = 2;
const int highestPin = 13;


void setup() {
  // set pins 2 through 13 as outputs:
  for (int thisPin =lowestPin; thisPin <= highestPin; thisPin++) { 
    pinMode(thisPin, OUTPUT); 
  }
}

void loop() {
  // iterate over the pins:
  for (int thisPin =lowestPin; thisPin <= highestPin; thisPin++) { 
    // fade the LED on thisPin from off to brightest:
    for (int brightness = 0; brightness < 255; brightness++) {
      analogWrite(thisPin, brightness);
      delay(2);
    } 
    // fade the LED on thisPin from brithstest to off:
    for (int brightness = 255; brightness >= 0; brightness--) {
      analogWrite(thisPin, brightness);
      delay(2);
    } 
    // pause between LEDs:
    delay(100);
  }
}

Moderator edit:
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</mark> <mark>[/code]</mark> <mark>
tags added.

2

What did you want to make random? The order of pins? The maximum brightness? The minimum brightness?

3

i want the led's to fade in a random pattern The order of pins

4

markthespark:
i want the led's to fade in a random pattern The order of pins

Does it matter if each LED fades once (in random order) before any LED fades a second time?

If not it's fairly easy. Instead of:

  for (int thisPin =lowestPin; thisPin <= highestPin; thisPin++) {

put:

  { int thisPin = random(lowestPin, highestPin+1);
5

hi thanks
thats great it does not matter if each LED fades once

6

You might want to know, while it will be a random order, this code will result in the same random order every time.
Try using some real-world data as a random seed (analogRead() on an unconnected pin? Not the best method but suitable for something like this), or the excellent entropy library by wanderson: Google Code Archive - Long-term storage for Google Code Project Hosting.