next topic »

[on:]

I'm new to Arduino and I'm still just figuring out the basics and I can't seem to figure out what's wrong with the coding or if I'm going about it the wrong way.  I'm trying to make it so when you press a push button a circuit will turn on and stay on until it is pushed again, and be able to do this over and over.



int blue=12;// 1st LED
int red=10;//2nd LED
int yellow=11;//3rd LED
int buttonpin=2;
int reading;//push button state
int ctr=0;//counter for button presses


void setup(){
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(blue, OUTPUT);
  pinMode(buttonpin, INPUT);
}

void loop(){
  reading=digitalRead(buttonpin);//reads the push button

    if(reading==HIGH){
      ctr++;//if button is pressed, counter goes up by one
  }
  //I figured when you want the circuit ON the button
  //will have been pushed an odd amount of times so the
  //LEDs blink on and off when ctr is odd
    if(ctr%2!=0){

    digitalWrite(yellow,HIGH);
    digitalWrite(red,LOW);
    digitalWrite(blue,LOW);
    delay(100);
   
    digitalWrite(yellow,LOW);
    digitalWrite(red,HIGH);
    digitalWrite(blue,LOW);
    delay(100);
   
    digitalWrite(yellow,LOW);
    digitalWrite(red,LOW);
    digitalWrite(blue,HIGH);
    delay(100);
   
    digitalRead(buttonpin);

    }
  //LEDs turn off when ctr is even
  if(ctr%2==0){
  digitalWrite(yellow,LOW);
  digitalWrite(red,LOW);
  digitalWrite(blue,LOW);
}
}
   

Any help that anyone can provide is greatly appreciated.

Thanks. 
   
   
 
   

[Reply #1 on:]

To use a momentary push-button as a toggle switch, you need to use a technique called signal edge detection. Knowing when the button is HIGH or LOW isn't going to help because the loop will run thousands of times per second. What you need is to find the moment where the button switches states, called the signal edge. To do this, you simply need to keep track of what the last reading was and compare it to the current reading.

[Reply #2 on:]

you never reset the button variable so after the first time it is always !=0

your also not keeping track of single pushes, the loop is running millions of times a second so if you printed out your counter to the serial monitor, I bet it skyrockets very quickly (use the serial monitor like it was your air supply when figuring things out!)

so in a practical application ... something like

Code:

// bytes are half the size of int's, but restricted to a max value of 255
byte button;
byte oldbutton = 0;
byte buttonpin = 2;
byte state = 0;

void setup()
{
  pinMode(buttonpin, INPUT);
}

void loop()
{
  digitalRead(buttonpin);
  if(button && !oldbutton) // same as if(button == high && oldbutton == low)
  {
    //we have a new button press
    if(state == 0) // if the state is off, turn it on
    {
      //do stuff
      state = 1;
    }
    else // if the state is on, turn it off
    {
      //do stuff
      state = 0;
    }
    oldbutton = 1;
  }
  else if(!button && oldbutton) // same as if(button == low && oldbutton == high)
  {
    // the button was released
    oldbutton = 0;
  }
}

PS: highlight your code and hit the # icon in the editor for future reference, it makes life much easier

[Reply #3 on:]

You don't say what the problem is!- what's not going right for you here? Difficult to help if we don't know what's wrong...

In principle that would work yep, but switches have bounce in them and so that might be screwing your count.

What you're doing is similar to this but which debounces the switch as also explained here

Have you got a pull-down on the switch as shown in those links?- if not, its state might not be 0 when its not pressed.

And lastly a tip: please wrap your code in the code tags using the # button above the smilies- makes it muuuuuch easier to read.

HTH,

Jim

Edit.... oh yes, and what Osgeld said about the counter 

[Reply #4 on:]

Thanks everyone for the help.  Osgeld I ended up basing my final code on what you put up with some extra things to make it work for my specific project.