Code with blocks Arduino LEDs ON/OFF with one push button

[est_1]

Hello

I have an Arduino UNO and switch pushbuttons with protectors like this:

I want to code an interruptor so that when press the pushbutton, two LEDs go HIGH, and when pressing again they go LOW.

I have searched the following help links:

• https://docs.arduino.cc/built-in-examples/digital/Debounce/
• https://www.instructables.com/Arduino-Light-Switch/
• Circuit design Arduino Led ON/OFF control with one push button - Tinkercad

I need to understand the basics for the kids. We use blocks to code. We use Tinkercad for simulation and mBlock to translate the block-code solution into Arduino code. This is what I got:

Login - Tinkercad

Circuit:

Arduino code automatically generated by Tinkercad:

// C++ code
//
int buttonState = 0;

int timesPressed = 0;

void setup()
{
  pinMode(2, INPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
}

void loop()
{
  buttonState = digitalRead(2);
  if (buttonState == HIGH) {
    digitalWrite(11, HIGH);
    digitalWrite(12, HIGH);
    timesPressed = (timesPressed + 1);
    if (timesPressed % 2 == 0) {
      digitalWrite(11, LOW);
      digitalWrite(12, LOW);
      timesPressed = 0;
    }
    delay(100); // Wait for 100 millisecond(s)
  }
}

Block-based solution:

Problem:

Sometimes it bugs, flashing the LEDs or even having to press twice for the LEDs to change state:

Question:

What can be improved from the code (if possible, a block-based answer)? Why does they flash or have to press twice in order to change the LEDs state?

Considerations:

• At this time I am unable to test the code in real life.
• Of course I could use an interruptor like this:
  
  
  
  But we don't have one, so a push button is mandatory.

Thank you!

[LarryD]

@est_1

Arduino code automatically generated by Tinkercad

• What does this mean ?

[est_1]

Thank you for your fast answer!

@Delta_G

Probably have a bouncy switch. You can add code to debounce it in software or a small capacitor across the pins to handle it with hardware.

I've read about debouncing and stuff, but in order to solve it you mean to code the solution using https://docs.arduino.cc/built-in-examples/digital/Debounce/?

@Delta_G

Your code has a bug. Whenever the button is pressed you should decide whether to turn on or off and then do that. Right now you turn it on every time and then decide whether or not to immediately turn it back off.

Oh, I see.

The code without bug should change a lot from the initial code? Can you help me, please?

[est_1]

@LarryD

• What does this mean ?

The kids and I code with blocks.

Go to Tinkercad, start a new project (circuit), drag the components and code with blocks. Then go to the Text view and copy the generated Arduino code

[LarryD]

• When writing code for switch operations, look for a change in switch state i.e. when the switch changes from a HIGH to a LOW or vice versa.
  Do not look at the current level of the switch.

[est_1]

@Delta_G

Your code has a bug. Whenever the button is pressed you should decide whether to turn on or off and then do that. Right now you turn it on every time and then decide whether or not to immediately turn it back off.

I was thinking maybe using another if condition to avoid immediate change of state, but I couldn't. Any ideas?

[est_1]

@LarryD

When writing code for switch operations, look for a change in switch state i.e. when the switch changes from a HIGH to a LOW or vice versa.
Do not look at the current level of the switch.

I was thinking about these and tried with the following blocks:

// C++ code
//
int buttonState = 0;

int timesPressed = 0;

void setup()
{
  pinMode(2, INPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
}

void loop()
{
  buttonState = digitalRead(2);
  if (buttonState == HIGH) {
    digitalWrite(11, HIGH);
    digitalWrite(12, HIGH);
    timesPressed = (timesPressed + 1);
  }
  if (buttonState == LOW) {
    if (timesPressed % 2 == 0) {
      digitalWrite(11, LOW);
      digitalWrite(12, LOW);
      timesPressed = 0;
    }
  }
  delay(100); // Wait for 100 millisecond(s)
}

It still requires that sometimes have to press more than once, but at least the flickering problem seems to have disappeared.

Also, I put wait 0.1 seconds out the if but I don't know if it is correct.

[LarryD]

• Not tested

• Try this to see how things react.

//================================================^================================================

#define PRESSED          HIGH
#define RELEASED         LOW

#define LEDon            HIGH
#define LEDoff           LOW

const byte mySwitch    = 2;
const byte firstLED    = 11;
const byte secondLED   = 12;

byte timesPressed;
byte buttonState;
byte lastButtonState   = LOW;


//================================================^================================================
void setup()
{
  pinMode(mySwitch, INPUT);
  
  pinMode(firstLED, OUTPUT);
  pinMode(secondLED, OUTPUT);

} //END of   setup()


//================================================^================================================
void loop()
{
  buttonState = digitalRead(mySwitch);

  //has there been a change in the switch's state ?
  if (lastButtonState != buttonState)
  {
    //update to this new state
    lastButtonState = buttonState;

    //poor mans de-bounce
    delay(50); //wait for 50 millisecond(s)

    //has the switch been pressed ?
    if (buttonState == PRESSED)
    {
      digitalWrite(firstLED, LEDon);
      digitalWrite(secondLED, LEDon);
      timesPressed = (timesPressed + 1);
    }

    //has the switch been released ?
    else if (buttonState == RELEASED)
    {
      if (timesPressed % 2 == 0)
      {
        digitalWrite(firstLED, LEDoff);
        digitalWrite(secondLED, LEDoff);
        timesPressed = 0;
      }
    }
  }
  
} //END of   loop()


//================================================^================================================