ESP32 - Button Count - OLED

In this tutorial, we will explore ESP32 to achieve the following objectives:

Additionally, the tutorial addresses the debouncing of the button without utilizing the delay() function. For an understanding of why debouncing is essential, refer to the explanation provided in Why do we need debouncing?.

This comprehensive guide will help you integrate button press counting, OLED display functionality, and debouncing techniques seamlessly with your ESP32 project.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×USB Cable Type-C
1×Push Button
1×(Optional) Panel-mount Push Button
1×SSD1306 I2C OLED Display 128x64
1×Breadboard
1×Jumper Wires
1×(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
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Introduction to OLED and Button

Unfamiliar with OLED and button, including their pinouts, functionality, and programming? Explore comprehensive tutorials on these topics below:

Wiring Diagram

ESP32 Button OLED Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

ESP32 Code - displaying button count on OLED

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-button-count-oled */ #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #include <ezButton.h> #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C ezButton button(27); // create ezButton object that attach to the ESP32 pin GPIO27 unsigned long lastCount = 0; void setup() { Serial.begin(9600); // initialize OLED display with address 0x3C for 128x64 if (!oled.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { Serial.println(F("SSD1306 allocation failed")); while (true); } delay(2000); // wait for initializing oled.clearDisplay(); // clear display oled.setTextSize(2); // text size oled.setTextColor(WHITE); // text color oled.setCursor(0, 10); // position to display button.setDebounceTime(50); // set debounce time to 50 milliseconds button.setCountMode(COUNT_FALLING); } void loop() { button.loop(); // MUST call the loop() function first unsigned long count = button.getCount(); if (lastCount != count) { Serial.println(count); // print count to Serial Monitor oled.clearDisplay(); // clear display oled.println(count); // display count oled.display(); // show on OLED lastCount != count; } }

Quick Instructions

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
  • Do the wiring as above image.
  • Connect the ESP32 board to your PC via a micro USB cable
  • Open Arduino IDE on your PC.
  • Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
  • Click to the Libraries icon on the left bar of the Arduino IDE.
  • Search “ezButton”, then find the button library by ArduinoGetStarted
  • Click Install button to install ezButton library.
ESP32 button library
  • Search “SSD1306”, then find the SSD1306 library by Adafruit
  • Click Install button to install the library.
ESP32 OLED library
  • You will be asked for intalling some other library dependencies
  • Click Install All button to install all library dependencies.
ESP32 Adafruit GFX sensor library
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to ESP32
  • Press button several times
  • See the counting number changed on OLED

The above code just displays the button press count on the top left corner. Let's modify the code to centralize it!

ESP32 Code - Vertical and Horizontal Center Align on OLED

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-button-count-oled */ #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #include <ezButton.h> #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C ezButton button(27); // create ezButton object that attach to the ESP32 pin GPIO27 unsigned long lastCount = 0; void setup() { Serial.begin(9600); // initialize OLED display with address 0x3C for 128x64 if (!oled.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { Serial.println(F("SSD1306 allocation failed")); while (true); } delay(2000); // wait for initializing oled.clearDisplay(); // clear display oled.setTextSize(2); // text size oled.setTextColor(WHITE); // text color oled.setCursor(0, 10); // position to display button.setDebounceTime(50); // set debounce time to 50 milliseconds button.setCountMode(COUNT_FALLING); } void loop() { button.loop(); // MUST call the loop() function first unsigned long count = button.getCount(); if (lastCount != count) { Serial.println(count); // print count to Serial Monitor String text = String(count); oledDisplayCenter(text); lastCount != count; } } void oledDisplayCenter(String text) { int16_t x1; int16_t y1; uint16_t width; uint16_t height; oled.getTextBounds(text, 0, 0, &x1, &y1, &width, &height); // display on horizontal and vertical center oled.clearDisplay(); // clear display oled.setCursor((SCREEN_WIDTH - width) / 2, (SCREEN_HEIGHT - height) / 2); oled.println(text); // text to display oled.display(); }

※ NOTE THAT:

The about code automatically horizontal and vertical center aligns the text on OLED display. See How to vertical/horizontal center on OLED for more detail.

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