How to use button to start/stop the loop?

How can I start the loop if a button is pressed, stop the loop if the button is pressed again in Arduino? This process is repeated forever.
Answer

Let's see and compare the code WITHOUT and WITH the start/stop button.

Arduino Code WITHOUT the Start/Stop Button.

void setup() { /******************* * your setup code *******************/ } void loop() { /****************** * your loop code ******************/ }

Arduino Code WITH the Start/Stop Button.

#include <ezButton.h> #define LOOP_STATE_STOPPED 0 #define LOOP_STATE_STARTED 1 ezButton button(7); // create ezButton object that attach to pin 7; int loopState = LOOP_STATE_STOPPED; void setup() { /******************* * your setup code *******************/ button.setDebounceTime(50); // set debounce time to 50 milliseconds } void loop() { button.loop(); // MUST call the loop() function first if (button.isPressed()) { if (loopState == LOOP_STATE_STOPPED) loopState = LOOP_STATE_STARTED; else // if(loopState == LOOP_STATE_STARTED) loopState = LOOP_STATE_STOPPED; } if (loopState == LOOP_STATE_STARTED) { /****************** * your loop code ******************/ } }

The wiring diagram for above code:

How to use button to start/stop program

Image is developed using Fritzing. Click to enlarge image

If you want to use a button to start the program only when the button is pressed the first time, see Arduino - using a button to start the program

※ NOTE THAT:

  • In this case, we SHOULD debounce the button. If not, the code may not work as expected.

Hardware for above code

1 × Arduino UNO Buy on Amazon
1 × USB 2.0 cable type A/B Buy on Amazon
1 × Button Buy on Amazon
1 × Breadboard Buy on Amazon
1 × Jumper Wires Buy on Amazon
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