Turning on random LEDs using a pushbutton.

Projects Programming
21

While figuring out buttons I found this code on these forums. It's quite easy to follow and demonstrates state changes.

State changes are what you really want to keep track of. What most people call a button press is really a press and release.

/*
 * Sample sketch to show how to detect the state changes of a momentary switch (button). 
 * Debounce is also implemented without the use of delay and the length that the button
 * is pushed down for is printed to the serial monitor.
 */
 
const int buttonPin = 2;
const unsigned long debounceInterval = 20; // Increase until bouncing stops

unsigned long debounceTime = 0;
unsigned long buttonPushedDownTime = 0;
int lastReading = HIGH;
int lastState = HIGH;
int currentState = HIGH;

void setup()
{
  pinMode(buttonPin, INPUT_PULLUP);
  Serial.begin(115200);
  Serial.println("[start]");
}

void loop()
{
  
  unsigned long currentTime = millis();// Store the current time in a variable for easy access
  unsigned long lengthButtonWasDown = 0;// This variable will be used to store the length of time that the button was depressed for
  int currentReading = digitalRead(buttonPin);// Start by getting the current reading from our button
  if (currentReading != lastReading) debounceTime = currentTime;  // If it's different than our last reading, reset the debounce timer
  if (currentTime - debounceTime > debounceInterval) currentState = currentReading;  // If the button has stayed at the same reading for long enough, update the button's state

  // At this point, the debounce is taken care of, we just need to look for the signal edges
  // of the button. That is, when the button goes from LOW to HIGH or HIGH to LOW.
  if (currentState != lastState)
  {
    // First we check if this which transistion we have. If the button is pushed down, then
    // the currentState will be LOW. Otherwise, the button is being released.
    if (currentState == LOW)
    {
      Serial.println("Button pushed down");
      buttonPushedDownTime = currentTime;
    }
    else
    {
      // Calulate how long it was pushed down
      lengthButtonWasDown = currentTime - buttonPushedDownTime;
      // Print the results to the Serial monitor
      Serial.print("Button realeased after ");
      Serial.print(lengthButtonWasDown);
      Serial.print(" seconds");
      
    }
  }
  
  // Update the "last" variables
  lastReading = currentReading;
  lastState = currentState;
}
22

Darwoon:
Official documentation is "sometime"s helpfull : http://arduino.cc/en/Tutorial/Debounce (how to debounce a button input)

That's what I said...

23

will this work
help me PaulS

const int button1Pin = 2;
const int button2Pin = 3;
const int ledPin = 13;
const int ledPin1 = 12;
const int ledPin2 = 8;
const int maxLedPins = 3;

int ledpins[maxLedPins] = {ledPin, ledPin1, ledPin2};

void setup()
{
pinMode(button1Pin, INPUT);
pinMode(button2Pin, INPUT);
pinMode(ledPin, OUTPUT);
pinMode(ledPin1, OUTPUT);
pinMode(ledPin2, OUTPUT);
pinMode(ledPin3, OUTPUT);
pinMode(ledPin4, OUTPUT);
}

void loop()
{
int button1State, button2State;
int button1State = digitalRead(button1Pin);
int button2State = digitalRead(button2Pin);
if(one && two) // Both are pressed
{
// Do NOTHING
}
else if(one) // Only switch one is pressed
{
// Light a random LED
}
else if(two) // Only switch two is pressed
{
// Turn all LEDs off
}
else // Neither switch is pressed
{
// Do nothing
}
digitalWrite (ledpins[random(maxLedPins)], HIGH);
}
else
{
digitalWrite(ledPin, LOW);
digitalWrite(ledPin1, LOW);
digitalWrite(ledPin2, LOW);
}
}

24

will this work
help me PaulS

PM me. I'll reply with an address. You can mail me your Arduino, with LEDs connected, and I'll compile and link and upload the code, and tell you that it indeed works, for some definition of work.

That definition, of course, might not be YOUR definition of work.