LED brightness control with two push buttons

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hi everyone.
I got an arduino a couple of days ago and allready having trouble with my fist project. I want control the brightnes of three leds with 2 pushbuttons. One for increasing the brightnes and the other for decreasing.

The circuit is simple. Two pushbuttons with pulldown resistors to pins 2 and 4.
The leds are conected through resistors to pins 11, 5 and 6.

I 've set 5 levels of brightness using a counter variable. The counter determines the PWM value that is sent to the leds. The problem is that eventhough the counter works fine, the PWM value is incorrect when brightness goes all the way up or down, or when i switch from brightness up to brightness down.

Here is the code:

//Variables won't change
const int lamp1 = 11;      //led #1
const int lamp2 = 5;       //led #2
const int lamp3 = 6;       //led #3
const int upPin = 2;      //button for brightnes up
const int downPin = 4;    //button for brightnes down


//Variables will change
int lastCounter = 3;
int counter;              //the basic counter
int up;                   //brightnes up button reading
int down;                 //brightnes down button reading
int volt;                 //PWM value sent to the leds

void setup(){
  pinMode(up, INPUT);
  pinMode(down, INPUT);
  Serial.begin(9600);

  
}

void loop(){
  counter = lastCounter;      //counter recyrculation
  up = digitalRead(upPin);        //button pins reading
  down = digitalRead(downPin);
  

  
   if (up == HIGH) {                    //if the up button is pressed
      counter = counter++;              //counter increases by one
      Serial.println("Counter");
      Serial.println(counter);
      Serial.println("PWM");
      Serial.println(volt);
    }
   
  


  
    
    if (down == HIGH) {            //if down button is pressed
        counter = counter--;       //counter decreases by one
        Serial.println("Counter");
        Serial.println(counter);
        Serial.println("PWM");
        Serial.println(volt);
      }
    
    
  if (counter > 5){      //check that counter won't get further than 5
    counter = 5;
  }
  
  if (counter < 2){    //check that counter won't fall bellow 1
    counter = 1;
  }
 
  switch (counter){    //depending on counter value the propper PWM value is sent to the leds
  
  case 1:
  volt = 50;
  break;
  
  case 2:
  volt = 100;
  break;
  
  case 3:
  volt = 150;
  break;
  
  case 4:
  volt = 200;
  break;
  
  case 5:
  volt = 250;
  break;
  
  }
  
 
 
  
  analogWrite(lamp1, volt);    //leds turn on with the desirable PWM
  analogWrite(lamp2, volt);
  analogWrite(lamp3, volt);
  
  lastCounter = counter;      //counter recylculation
  
  
  delay(500);              
  
}

I thing the problem lyies in the switch command.

Any thoughts?

BTW my english sucks, working on improving it!!

Thanks.

2

Does this help...

   if (up == HIGH) {                    //if the up button is pressed
      [glow]counter++;[/glow]              //counter increases by one
      Serial.println("Counter");
      Serial.println(counter);
      Serial.println("PWM");
      Serial.println(volt);
    }

    if (down == HIGH) {            //if down button is pressed
        [glow]counter--;[/glow]       //counter decreases by one
        Serial.println("Counter");
        Serial.println(counter);
        Serial.println("PWM");
        Serial.println(volt);
      }
3

I'm afraid not. The problem reamains.

4

the PWM value is incorrect

You print the PWM value before it has been modified. Could the problem be that you're printing the value too soon?

5

In each if test, you are changing the value of counter, printing the value of counter, then printing the vale of volt.

Then, you change the value of volt, in a most inefficient way. The end result of the whole switch statement is that volt = 50 * counter. Just setting volt to 50 * counter is much more efficient.

After setting volt is the time to print it, not before.

What's with lastCounter? The last instruction in loop is lastCounter = counter;, and the first instruction in loop is counter = lastCounter;. Both are global values, so one is unneeded.

6

Yes, but how could i print volt just once after each button press. If i print it somewhere else it would be print twice a second in each loop.

The lastCounter thing is useless, you are right.

7

That's a good point. But, you should make the change to volt before you print it. Since it's an easy calculation, just do it in the if body.

8

Well, i've just noticed that buttons work just fine with the leds. I was stuck stairing at the serial monitor wich was really really confusing and ignored the leds.

Won't happen again. Promise!! :-[

Thanks a lot guys!

9

Something like this should work...

// other existing code stays here

   if (up == HIGH) {                    //if the up button is pressed
      counter = counter++;              //counter increases by one
      Serial.println("Counter");
      Serial.println(counter);
// two lines removed
    }

    if (down == HIGH) {            //if down button is pressed
        counter = counter--;       //counter decreases by one
        Serial.println("Counter");
        Serial.println(counter);
// two lines removed
      }

// exist code that sets volt stays here

   if ( (up == HIGH) || (down == HIGH) ) {            //if down button is pressed
      Serial.println("PWM");
      Serial.println(volt);
  }

  analogWrite(lamp1, volt);    //leds turn on with the desirable PWM
  analogWrite(lamp2, volt);
  analogWrite(lamp3, volt);

// other existing code stays here
10

Made those changes and the serial monitor works fine as well!!!

Thanks!