Arduino Ultrasonic Range Finder, With I²C Lcd Display!





Introduction: Arduino Ultrasonic Range Finder, With I²C Lcd Display!


in this project i want to show and explain you a range sensor with ultrasonic and a 20x04 lcd screen. I wrote the code for this project myself and added lots of comments, so that everybody can understand it and use it for other projects (maybe a light range sensor?!). It is easy to build and much more easier to program, it just requires a few cheap parts and can run on battery, for a portable rangefinder.

The maximum rated range is 500 cm, the range is measured 20 times per seccond. It is Displayed on a lcd screen which is 20x4 chars big, it has a custom start message, and it can have a custom design while measuring. It will have a backlight LED and can run on every arduino, which has I²C communication. That mean you can run it on an Arduino nano, which is very small. It also requires 5V so it has to be a 5V version of an Arduino.

Step 1: What Do You Need & Tools

We dont need much things, the parts should be less then 15$ (without arduino, with arduino may 25-35$):


Arduino (5-55$) ,
Ultrasonic sensor (2$),  HC-SR04  ,
A 20x4 Display (6$) ,
A IIC/I2C/TWI/SP​​I Serial Interface Board Module (2$) ,
Some wires
a Breadboard
A USB cable


Arduino ,

wire.h library (should be with the Arduino software)
LiquidCrystal_I2C.h library  for the Display
NewPing.h library for the sensor


what are tools? D:

(no tools needed, yay)


a Case...

Step 2: The Display

Now we need to connect the IIC I2C TWI SPI Serial Interface Board Module to the display, that allows us to easily use the Display with the I²C bus of the Arduino ( nearly every Arduino/Atmel processor can communicate with I²C, it just need a SDA and a SCL pin). Solder the module to the display ( picture 2 ).

Take care of the heat, it can easily destroy the display and the module!!!

Step 3: The Sensor

The ultrasonic sensor is a very good one, its part number is HC-SR04, it is one with a range of 1cm-500cm. It is a good build one, which is easy to handle and to use.

Step 4: Assembly

Lets assembly it, plug the VCC pins of the Display and the Sensor to the +5V pin of the Arduino, plug the GND pins of the Display and the Sensor to GND of the Arduino.

Now plug the TRIG pin of the Ultrasonic Sensor to pin 12 of your Arduino
and the ECHO pin to pin 11 of your Arduino.


VCC -> +5V
GND -> 0V
TRIG -> pin 12
ECHO -> pin 11

Plug the SDA pin of the display to pin A4 of your Arduino
and the SCL pin of the display to A5 of your Arduino


VCC  -> +5V
GND -> 0V
SDA -> A4
SCL -> A5

Step 5: Code

Now my favorite chapter, because i wrote the code myself, what made my day, beacuse im not such a good programmer :)

The code is made for the Arduino Uno, you can find it here:

I wrote many commands, to help you understanding it.

You can add a custom startup message (line 57), also you can add a custom design while measuring ( line 87 )

Feel free to comment bugs, addictions and things to make it better!!! :)
Also feel free to comment if you amde the code for other processors (like the Attiny85)!!

Step 6: Finishing


Now your first self build arduino range sensor should work!! congratulations!!


Code it for other processors/platforms
make a nice case
use other parts


Display shows bars:

unplug power source, then wait 5 secconds and plug it in again. Sometimes there is a bug, that the display dont refresh :/

may SDA and SCL are reversed

Sensor dont work:

TRIG and ECHO are switched

Display, Arduino and LED´s fade out:

you made a short circuit, unplug your power source immediately!!!!

Other Pages:

Thank you for Reading, feel free to comment and Vote for me in a Contest!!!

greets Jan Henrik



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    sketch_sep02a.ino:23:53: error: 'POSITIVE' was not declared in this scope,

    it gives me this eror how can I fix


    my sketch is kind of outdated, I will update it as soon as I can :)

    i'm using I2C/TWI 1602 and a 16X2 display , did i wrongly connect the twi interface to the display?

    oh, did you change the code for a 16x2 display? I used a 16x4

    what is mean by switching sda and scl , is my interface connection is correct.please check it , deadline to submit my project is fast approaching.please reply


    thats interresting, has your display the right controller for the i²c interface?

    Display showing bars instead of characters .. what's de solution?

    i 'm getting an error POSITIVE not declared under this scope.Tell me the correct LCD library