ESP32 - Ultrasonic Sensor - OLED

This tutorial instructs you how to use ESP32 to read the distance from ultrasonic sensor and display it on an OLED.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	Micro USB Cable
1	×	SSD1306 I2C OLED Display 128x64
1	×	Ultrasonic Sensor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) 5V Power Adapter
1	×	(Optional) DC Power Jack
1	×	(Optional) ESP32 Screw Terminal Adapter

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Introduction to OLED and Ultrasonic Sensor

We have specific tutorials about OLED and Ultrasonic Sensor. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:

ESP32 - OLED tutorial
ESP32 - Ultrasonic Sensor tutorial

Wiring Diagram

The wiring diagram with power supply from USB cable

This image is created using Fritzing. Click to enlarge image

The wiring diagram with power supply from 5v adapter

ESP32 Ultrasonic sensor OLED 5V power wiring diagram

This image is created using Fritzing. Click to enlarge image

ESP32 Code - Ultrasonic Sensor - 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-ultrasonic-sensor-oled */ #include <Wire.h> #include <Adafruit_GFX.h> #include <Adafruit_SSD1306.h> #define SCREEN_WIDTH 128 // OLED display width, in pixels #define SCREEN_HEIGHT 64 // OLED display height, in pixels #define TRIG_PIN 14 // ESP32 pin GIOP14 connected to Ultrasonic Sensor's TRIG pin #define ECHO_PIN 27 // ESP32 pin GIOP27 connected to Ultrasonic Sensor's ECHO pin Adafruit_SSD1306 oled(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1); // create SSD1306 display object connected to I2C String tempString; 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 tempString.reserve(10); // to avoid fragmenting memory when using String } void loop() { // generate 10-microsecond pulse to TRIG pin digitalWrite(TRIG_PIN, HIGH); delayMicroseconds(10); digitalWrite(TRIG_PIN, LOW); // measure duration of pulse from ECHO pin long duration_us = pulseIn(ECHO_PIN, HIGH); // calculate the distance float distance_cm = 0.017 * duration_us; // print the value to Serial Monitor Serial.print("distance: "); Serial.print(distance_cm); Serial.println(" cm"); tempString = String(distance_cm, 2); // two decimal places tempString += " cm"; Serial.println(tempString); // print the temperature in Celsius to Serial Monitor oledDisplayCenter(tempString); // display temperature on OLED } 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(); }

Quick Instructions

Open Arduino IDE, Go to Tools Manage Libraries

Search “SSD1306”, then find the SSD1306 library by Adafruit
Click Install button to install the library.

You will be asked for intalling some other library dependencies
Click Install All button to install all library dependencies.

Copy the above code and paste it to Arduino IDE
Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
Move your hand in front of sensor
See the result on OLED and Serial Monitor

※ 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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