ESP32: Pocket Size Distance Measuring and Logger

About: Born in Pluto, Raised in Mars

This is a sonic (sound-based), pocket-size measuring tool, accurate up to 3mm. It is useful for applications where you want to log the distances or find distances that are inaccessible, therefore measuring tapes, rulers, and callipers are out of the question!

Since the ESP32 is such a tiny micro controller powered by a micro usb port, you can grab a small power bank, plug it in, and start measuring distances normally inaccessible with conventional means of measuring i.e. rulers.

Step 1: Materials and Tools

  • ESP32
  • Ultrasonic Sensor (HC-SR04)
  • Breadboard
  • Breadboard wires

Step 2: Connecting the Ultrasonic Sensor

  • Connect the VCC pin to 3.3V on the ESP32
  • Connect the GND pin to ground on the ESP32
  • Connect the Trig pin to D2 on the ESP32
  • Connect the Echo pin to D5 on the ESP32

Step 3: Coding and Uploading

Plug in your ESP32 to the computer and upload the following code to the ESP32 board. Make sure you have selected the correct board and port both will be labeled with ESP32.

// defines pins numbers
const int trigPin = 2;
const int echoPin = 5;
// defines variables
long duration;
int distance;
void setup() {
pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input
Serial.begin(9600); // Starts the serial communication
void loop() {
// Clears the trigPin
digitalWrite(trigPin, LOW);
// Sets the trigPin on HIGH state for 10 micro seconds
digitalWrite(trigPin, HIGH);
digitalWrite(trigPin, LOW);
// Reads the echoPin, returns the sound wave travel time in microseconds
duration = pulseIn(echoPin, HIGH);
// Calculating the distance
distance= duration*0.034/2;
// Prints the distance on the Serial Monitor
Serial.print("Distance: ");

Step 4: Aim and Test!

Aim it at a distant object, like the wall or ceiling and measure! Try blocking it with your hand and watch the values change accurately and precisely.



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    7 Discussions


    5 days ago

    i have followed every step but got this error.. plz guide


    24 days ago

    Worked fine when I used V in instead of 3,3 volt .
    Thank you for this guide and the code.


    24 days ago

    Tried this but My HC-SR04 Sensor did not work with 3,3 volt that esp 32 deliver.
    Worked fine with my arduinio uno and 5 volts and of course different code.


    1 year ago

    Hey TechMartian, Its an amazing project but I would recommend exterior designing by 3D Printing. It would be better if you even add a lcd display or oled small display. Keeping an external power supply would be even better.

    But still your project is amazing. Keep it up!!!

    1 reply

    I thought about this too! Unfortunately I don't own a 3D printer so I couldn't make it. Maybe if our team wins the makerspace contest I can make an Instructables on it!


    Tech Martian


    1 year ago

    Handy gadget! If I may offer a suggestion: it'd be nice to have some sort of indicator or laser attachment to clearly identify what object's distance is being measured. Might make the "pocket-sized" criteria a bit more difficult, but just a thought. :)

    1 reply

    Reply 1 year ago

    Yes that's coming up but since it's gonna be big anyway gonna make it on my Arduino 101. Stay Tuned!