Push button with ESP32 – GPIO pins as digital input

Push button with ESP32 – GPIO pins as digital input, In this fifth tutorial on series of ESP32 tutorials, we will teach you how to use GPIO pins of ESP32 as digital input pins and how to interface a push button with the ESP32 development board.  The push button is used to control device like turning on and off a light emitting diode when the push button is pressed or not. Similarly, we can use push button to increase or decrease speed of dc motor. When you use push button with ESP32, we have to use GPIO pins as digital input pins. Because we will read the state of the push button. The push button will give two logical states either high or low.

Push button interfacing with ESP32

  • The push button can be interfaced with ESP32 either through pull up resistor or pull-down resistor. In Pull up resistor mode, when the push button is not pressed, input to GPIO pin will be logical high or vice versa.
  • In pull-down resistor mode, when the push button is pressed, input to GPIO pin will be logic low state and otherwise logic high state.

So We will use digital input pin of ESP32 development board to read this logical and logical low state using pinMode function of Arduino IDE.  So now let’s start with a circuit diagram of push button interfacing with esp32 and after that I will explain the programming part.

If you are a beginner and do not have an idea about ESP32 development board, you can check this guide:

Arduino IDE is used to program ESP32 in these series of tutorial and we can install ESP32 board in Arduino IDE. You can check this tutorial:

So now let’s perform a simple example to connect a push button with any GPIO pin and turn on an LED connected to another digital pin.  Push button and LED ESP32

As shown in the above pinout, we will be using GPIO15 to connect the push button and GPIO22 to connect a push button. We can use any GPIO pin either as digital input or digital output pins except few GPIO pins which can be used only as digital input pins for more information about it check ESP32 pin out the tutorial.

Circuit diagram of Push button with ESP32

Schematic is for push button interfacing is shown below:

Push button interfacing with ESP32

  • In the above circuit diagram, GPIO22 is connected with anode pin of LED and another pin of LED is connected with ground through 330ohm resistor.  you can check LED blinking tutorial for more information about it.
  • Next push button one terminal is connected with 3.3 volts of ESP32 and other terminals of a push button is common with GPIO15 and resistor.
  • Another end of the resistor is connected with a ground. When pushbutton is not pressed, logic low will appear on GPIO15 or push button state will be low and when the push button is pressed, a logic high will be on GPIO15.
  • So we will read these two states of the push button and turn on and turn off LED accordingly.

Code

Code for push button interfacing is given below. All the functions used in this code the same as used in the last tutorial on LED blinking except one function digitalRead function. So I will explain digital read function now:

digitalRead(Pin_number): Digital read function is used to read the state of the input pin. This digitalRead function returns either logical HIGH or logical LOW input. If input state of the pin is HIGH, it will return HIGH and otherwise low. You only need to pass pin number as a augment to this function. For example in this tutorial, we are using pin number 15 as a digital input, so we will use this function like this digitalRead(22) or we can define 22 with any name and use name instead of pin number as we did in the example code below:

// We assigned a name LED pin to pin number 22
const int LEDPIN = 22; 
// this will assign the name PushButton to pin numer 15
const int PushButton 
// This Setup function is used to initialize everything 
void setup()
{
// This statement will declare pin 22 as digital output 
pinMode(LEDPIN, OUTPUT);
// This statement will declare pin 15 as digital input 
pinMode(PushButton, INPUT);
}

void loop()

{
// digitalRead function stores the Push button state 
// in variable push_button_state
int Push_button_state = digitalRead(PushButton);
// if condition checks if push button is pressed
// if pressed LED will turn on otherwise remain off 
if ( Push_button_state == HIGH )
{ 
digitalWrite(LEDPIN, HIGH); 
}
else 
{
digitalWrite(LEDPIN, LOW); 
}
}

So this is the simple code used to read the state of push button or any switch.  So let’s see how the code works?

  • In code first 2 lines give a name to input pin 15 as PushButton and output pin 22 as LEDPIN. So now inside the code, we can use these name instead of pin numbers.
  • In  setup() function, we use pinMode() function to initialize PushButton pin as an INPUT and LEDPIN as an INPUT.
  • In loop() function, digitalRead function read the state of the push button and stores its value in variable Push_button_state.
  • After that, if condition is used to check the state of variable Push_button_state.
  • If Push_button_state gives output HIGH,  LEDPIN will be turned on and otherwise, it will remain off.

After going through this guide, you will surely able to use GPIO pins of ESP32 as a digital input pins. You can also check other ESP32 tutorials:

3 thoughts on “Push button with ESP32 – GPIO pins as digital input”

  1. Hi!

    But then the wiring has to be different – if you use internal pullup…

    in the Code:
    this line: const int PushButton
    should be: const int PushButton = 15

    or you use
    #define PB_PIN = 15
    #define LED_PIN = 22
    because there is no need to change the pin inside the Code

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