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Topic: Fading two LEDS  (Read 3481 times) previous topic - next topic

camillabrix

Hi

I am stuck trying to figure out the exercise seen below. I have managed to do the first part
but now I don't know how to add the other LED (the red part of the exercise)?? :smiley-sad:  :smiley-cry:


"EXERCISE 4

Make a LED fade up and down. The fade up should take 1 second
and the fade down should take 0.2 second.

When you have the above running, add another LED that does the opposite of the above,
so fade up = 1 second, fade down = 0.2 second"

AWOL


beige22

Hi! Can you upload the code you have so far so I can make a suggestion based on it?

Zerokj

I did this:

Code: [Select]
int led = X;
int brightness = 1;
int fadeAmount = 7;

void setup() {
 pinMode(led, OUTPUT);
}

void loop() {
 analogWrite(led, brightness);

 brightness = brightness + fadeAmount;

 if (brightness == 0 || brightness == 255) {
   fadeAmount = -fadeAmount ;
 }
 delay(0.2);
}


Im begginer, I couldn't understand what you need.
If you need to use 2 LEDs at once you have to sting the other LED with the same cables as the first one.
To both LEDs do the oposite each other, I don't know how to do.

It's my first day using Arduino and I started with LEDs and my Relay Module

Hugs, Zerokj

siutoejai

Quote
fade down = 0.2 second"
delay 1000     = 1 second

the delay should be 200      200/1000 = 0.2 second


delay(0.2) would not work as I know

the min is delay(1)


UKHeliBob

Quote
I have managed to do the first part
Perhaps we could see your code so far.


Are the 2 LEDs supposed to be fading up and down at the same time or one after the other ?
Please do not send me PMs asking for help.  Post in the forum then everyone will benefit from seeing the questions and answers.

mvmacd

#6
Apr 22, 2015, 09:11 pm Last Edit: Apr 22, 2015, 09:13 pm by mvmacd
Hi

I am stuck trying to figure out the exercise seen below. I have managed to do the first part
but now I don't know how to add the other LED (the red part of the exercise)?? :smiley-sad:  :smiley-cry:


"EXERCISE 4

Make a LED fade up and down. The fade up should take 1 second
and the fade down should take 0.2 second.

When you have the above running, add another LED that does the opposite of the above,
so fade up = 1 second, fade down = 0.2 second"

First take a look at http://www.arduino.cc/en/Reference/AnalogWrite
On most arduino boards, PWM outputs include 3, 5, 6, 9, 10, and 11.

Wire 2 LEDs, both cathodes to GND, and the anodes to pin 5, and pin 6 respectively.

Code: [Select]

int pin1 = 5; //PWM pin
int pin2 = 6; //PWM pin

void setup() {
 pinMode(pin1, OUTPUT);
 pinMode(pin2, OUTPUT);
}

byte number = 0;
bool goingUp = true; //This sets the direction
void loop() {
  
  if(goingUp) //this will be true the first time we run and true until we set it false
  {
      analogWrite(pin1, number);
      analogWrite(pin2, 255 - number); //write the opposite
      number++; //increase number
      if(number == 255)
      {
          goingUp = false; //switch direction, we reached the top
      }  
  }
  else //we are going down here
  {
       analogWrite(pin1, number);
       analogWrite(pin2, 255 - number);
      
       number = number - 5; //decrease number by a factor of 5
       //normally -1 means 1 second for 255 loops()
       //but we want 0.2 seconds, so that's a 1/5th of a second
       //so go 5 times faster than on the fadeUp
      
       if(number <= 0)
       {  
           goingUp = true; //switch direction again, going up
           number = 0; //just in case it went in the negative, reset to 0
       }
  }
  
  delayMicroseconds(3921); //IMPORTANT. for 3.9 milliseconds, we do nothing
  //This means roughly, every 255 cycles that equals 1 second
}

UKHeliBob

I just looked at the original requirement as follows :

Quote
Make a LED fade up and down. The fade up should take 1 second
and the fade down should take 0.2 second.

When you have the above running, add another LED that does the opposite of the above,
so fade up = 1 second, fade down = 0.2 second"
It seems to me that the second LED is not required to do the opposite of the first at all and it is still not obvious whether the fades should happen in series or parallel.
Please do not send me PMs asking for help.  Post in the forum then everyone will benefit from seeing the questions and answers.

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