Arduino Parking Assistant, Perfect For A Small Garage

Those of us who have small garages know the frustration of parking a little bit too far in or a little too far out and not being able to walk around the vehicle. We recently bought a larger vehicle, and it has to be parked perfectly in the garage to walk around the front and back. So here is an Arduino based parking assistant to help you park in exactly the same spot every time.

This project assumes you know the basics of Arduino programming, otherwise read our article on getting started with Arduino.

What You Will Need To Build An Arduino Parking Assistant


  • 1x 2×4 – at least 8″ long – Buy Here
  • 8x Philips Screws – Preferably 1″ Long – Buy Here
  • 1x Power Supply – 5 volt, 850mA – Buy Here
  • 1x Arduino Pro Mini – 5 volt, 16MHz – Buy Here
  • 1x HC-SR04 Ultrasonic Distance Sensor – Buy Here
  • 12x 220 ohm, 1/4 watt Resistors – Buy Here
  • 8x Green LEDs – 5mm – Buy Here
  • 4x Red LEDs – 5mm – Buy Here
  • 1x Tactile Pushbutton – 6mm – Buy Here
  • 3x Four Conductor Wire Sold by the Foot – 22 gauge – Buy Here


  • Wire Stripper
  • Bandsaw
  • Soldering Iron
  • Solder – I use 60/40 Rosin Core
  • Hot Glue Gun
  • Speed Square
  • Stick Glue
  • Philips Screwdriver
  • Pencil
  • Drill
  • 7/64″ Drill Bit – this depends on the size of your screws
  • 3/16″ Drill Bit
  • 1/4″ Drill Bit
  • 1″ Forstner Bit
  • Computer with the Arduino IDE
  • FTDI Programmer

How To Make Your Arduino Parking Assistant

Make The LED Display Box

led template to create led display box

The first step in this project is to make the enclosure. Print the PDF Pattern included below. Be sure you’re set to print at 100% scale. Now cut out the pattern and glue it to the 2×4. Be careful to line it up with the edges. It’s only temporary, so only glue it lightly.

LED Pattern.

cut the block with a band saw

Use your bandsaw to cut the 2×4 along the edge of the pattern. You could also use a chop saw or table saw.

cut the lid for the box

Now we need to turn this thing from a 2×4 into a box! Use your speed square to mark a line lengthwise on the side of the 2×4 about a quarter of an inch from the back of the box.

Go back to the bandsaw and cut directly on the line. This will cut a separate piece that will become our lid. You’ll be cutting close to your fingers; Please be careful!

the box lid cut off

Using your pencil, mark a rough square on the back of the larger block about a half inch from all the edges.

bore out the box

Now use your 1-inch to drill bore out the rectangle. You need to drill as deep as possible without coming through the front. Don’t drill too deep!

drill holes for the LEDs

Chock up your 3/16 inch drill bit and carefully drill each of the holes marked on the front of the pattern. I found it works best if you make a small indention with an awl before you drill.

Next drill a 3/16 inch hole roughly in the center of the bottom. This will be the hole for your calibration button.

Now use your 1/4 inch drill bit to drill two more holes in the bottom. These will be the holes for the wires.

add screws for the box lid

Now you’re done using the pattern. Peel it off as cleanly as possible.

Take the lid and lay it on the bottom. Turn it around if you have to, you need it in the original orientation.

Next use the 7/64 drill bit to drill a hole about a quarter of an inch from each corner. Drill about a quarter of an inch deep; don’t drill through the front!

Use the screwdriver and screws to fasten the lid.

You don’t have to, but it makes the box look a whole lot better if you give it a good, through sanding.

Add Electronics To The LED Display Box

The LEDs should be arranged in two rings; a large green ring on the outside with a smaller red ring inside that.

add the leds to the display box

Take a LED and stick it in a hole. Align it so the cathode (shorter lead) is toward the outside. Then put a little hot glue around it!

Repeat this process until all the LEDs are in their holes. Be careful to put the right color in the right hole!

sand the LEDs flush with the box

For a more seamless look, sand the LEDs flush with the wood. It works best to sand before the wires are in.

solder the leds together

Bend the shorter lead on a LED and touch it to the short leg on the next LED. Solder these two together and continue around the circle. A needle-nose pliers is a big help!

solder resistors the the leds

Cut a short length of wire, about two inches long, and strip it! Twist it around a leg of a resistor, it doesn’t matter which end. Use your soldering iron to make the connection permanent! Do this for all your resistors.

Next, grab a resistor-wire pair and carefully solder the free end of it to a LED. Be sure not to let the leads touch any other wires! Do this for each LED, and double-check for shorts.

Finally, solder a short length of wire to the leg that was left when you soldered the grounds.

solder and install the button

Cut and strip another short length of wire, and solder it to one of the button’s leads. Then clip all the button’s legs off except the one adjacent from your solder joint.

Place the button in the box so you can push it from the outside through the hole. Solder the free lead of the button to the ground connections of the LEDs.

Finally, drizzle a bit of hot glue over the button to keep it in place!

Install And Solder The Arduino

The circuit diagram for the Arduino is shown below.

arduino parking assistant circuit

Solder the pin-headers to the programming port of the Arduino. Then push the two wires (from the power supply and the one for the sensor) through their holes and use a bit of hot glue to keep them from falling out.

arduino soldered to the electronics

Strip the wires from the LEDs and button and solder them to the Arduino according to the wiring circuit diagram above.

Create The Parking Sensor Enclosure

create the sensor enclosure

The sensor enclosure is made in the same way as the LED display enclosure. This time, instead of making holes for the LEDs, make holes for the ultrasonic sensors as per the template below.

Sensor Enclosure.

ultrasonic sensors in enclosure

Connect The Parking Sensor Box To The Display Box

solder the sensor wires

Push the free end of the sensor wire through the hole in the box, then strip it and solder it to the sensor module as in the picture.

  • Black goes to GND
  • Blue goes to ECHO
  • Green goes to TRIG
  • Red goes to VCC

Use a bit of hot glue to secure the sensor in the case, then use another dab as stress relief for the cable. Screw the lid on, and you’re done!

Upload The Sketch

The Arduino is programmed using the FTDI Programmer which is connected to the Arduino using the jumpers and pins on the back. Once the programmer is connected to the Arduino, you can upload your sketch, if you haven’t uploaded a sketch before then follow this guide on getting started.

connections for programming the arduino

In order to read the sensor, we need the NewPing library. You can download it here, In the Arduino IDE, click on Sketch > Include Library > Add Zip Library… and point it the ‘’ folder.

include the ping sensor library

Open the sketch in the Arduino IDE and upload it to the Arduino.

#include <NewPing.h> //include the library for the sonar distance sensor
#include <EEPROM.h> //this lets us access the memory

const int G1 = 9;//set the led pins by the color
const int G2 = 8;
const int G3 = 7;
const int G4 = 6;
const int G5 = 5;
const int G6 = 4;
const int G7 = 3;
const int G8 = 2;
const int R1 = 13;
const int R2 = 12;
const int R3 = 11;
const int R4 = 10;
const int trigPin = A0; //set the distance sensor trigger pin to A0
const int echoPin = A1; //the sonar echo pin
const int buttonPin = A2; //the button

NewPing sonar(trigPin, echoPin, 300); //start the distance sensor

const int minDeviation = 5; //the number of inches of movement required to count as moving
const int timeout = 10; //the number of seconds to keep the leds on after movement stops
const int ledDistance = 6; //the distance in inches each led covers

int idealDistance = 5; //this is the perfect distance to the car read from the memory
int rawSonar; //this is the raw data from the distance sensor
int distance; //the distance to the vehicle
int prevDistance = 0; //the previous distance to the vehicle
unsigned long lastMoved = 0; //the millis reading of the last movement

void setup() { //this runs once at startup
	pinMode(G1, OUTPUT); //set the leds to output
	pinMode(G2, OUTPUT);
	pinMode(G3, OUTPUT);
	pinMode(G4, OUTPUT);
	pinMode(G5, OUTPUT);
	pinMode(G6, OUTPUT);
	pinMode(G7, OUTPUT);
	pinMode(G8, OUTPUT);
	pinMode(R1, OUTPUT);
	pinMode(R2, OUTPUT);
	pinMode(R3, OUTPUT);
	pinMode(R4, OUTPUT);

	pinMode(buttonPin, INPUT_PULLUP); //set button as input with internal pull-up resitors

	if ( != 255) { //read the memory, it will read 255 if it's never been written to
		idealDistance =; //set the idealDistance from the memory


void loop() { //this runs over and over again
	delay(100); //wait 100 ms to get accurate readings

	rawSonar = sonar.ping_median(5); //get 5 readings and average them
	if (rawSonar != 0) { //the distance sensor sends a 0 when nothing is in range
		distance = rawSonar / US_ROUNDTRIP_IN; //convert the raw data the inches
		distance -= idealDistance; //subtract the ideal distance from the reading, giving us the distance to go
	else {//if the car isn't in range
		setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //turn the LEDs off

	if (abs(distance - prevDistance) >= minDeviation) { //if the car has moved since last read
		lastMoved = 0; //reset the sleep timer

		prevDistance = distance; //reset the distance last read

		if (distance < ledDistance * 9 && distance >= ledDistance * 8) { //if it's in the 1st led's range
			setLEDs(1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 8 && distance >= ledDistance * 7) { //if in range of the 2nd led
			setLEDs(1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 7 && distance >= ledDistance * 6) { //if in range of the 3rd led
			setLEDs(1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 6 && distance >= ledDistance * 5) { //if in range of the 4th led
			setLEDs(1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 5 && distance >= ledDistance * 4) { //if in the 5th led
			setLEDs(1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 4 && distance >= ledDistance * 3) { //if in range of the 6th led
			setLEDs(1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 3 && distance >= ledDistance * 2) { //if in range of the 7th led
			setLEDs(1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0);
		else if (distance < ledDistance * 2 && distance >= ledDistance) { //if in range of the 8th led
			setLEDs(1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0);
		else if (distance <= idealDistance) { //if in the stop position
			setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1);
	else { //if the car isn't moving
		if (lastMoved == 0) { //if the timer hasn't been started
			lastMoved = millis(); //set the timer

		if (lastMoved != 0 && millis() - lastMoved >= timeout * 1000) { //if the timer is set and past the timeout
			setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //turn off the leds
			lastMoved = 0; //turn off the timer

	//this checks the button
	if (digitalRead(buttonPin) == LOW) { //if the button is being pressed
		rawSonar = sonar.ping_median(30); //get 30 readings and average them

		if (rawSonar != 0) { //the distance sensor sends a 0 when nothing is in range
			distance = rawSonar / US_ROUNDTRIP_IN; //convert the raw data the inches

			EEPROM.write(0, distance); //write the distance to the memory
			idealDistance = distance; //set the idealDistance

			flashGreen(); //show success
		else { //if out of range
			flashRed(); //show error

void flashGreen() { //this flashes the green LEDs to show success
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //clear the leds
	setLEDs(1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0); //turn the green leds on
	delay(500); //wait
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //turn all the leds off
	delay(500); //wait
	setLEDs(1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0); //turn the green leds on
	delay(500); //wait
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //turn the green leds off

void flashRed() { //this flashes the red LEDs to show success
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //clear the leds
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1); //turn the red leds on
	delay(500); //wait
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //turn all the leds off
	delay(500); //wait
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1); //turn the red leds on
	delay(500); //wait
	setLEDs(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); //turn all the leds off

//this function simply sets the leds to the parameters you send it
void setLEDs(int led1, int led2, int led3, int led4, int led5, int led6, int led7, int led8, int led9, int led10, int led11, int led12) {
	digitalWrite(G1, led1);
	digitalWrite(G2, led2);
	digitalWrite(G3, led3);
	digitalWrite(G4, led4);
	digitalWrite(G5, led5);
	digitalWrite(G6, led6);
	digitalWrite(G7, led7);
	digitalWrite(G8, led8);
	digitalWrite(R1, led9);
	digitalWrite(R2, led10);
	digitalWrite(R3, led11);
	digitalWrite(R4, led12);

Download The Sketch – ParkingSystem

Screw on the lid, and your parking assistant is ready to be installed.

Using the Arduino Parking Assistant

Mount The Parking Sensor And Display

Mount the sensor on your garage wall where it can sense a flat surface on your car’s bumper, not the grill! Mount the control box higher up where it’s visible from inside the vehicle.

Calibrating The Parking Sensor

Park your car in the best position, and use a long object like a pencil to push the button on the bottom. This will calibrate it. Be sure you’re not standing in front of the sensor!

When you drive into your garage, slowly approach the parking assistant; the green LEDs show your distance to the ideal parking spot, red shows you when to stop to park in the perfect position!

parking assistant in operation

parking assistant stopped

Have you built your own Arduino based parking assistant? Let us know in the comments section below.

This post is based upon Arduino Parking Assistant by addictedToArduino and is used and modified under the Creative Commons license CC-BY-NC-SA.

Michael Klements
Michael Klements
Hi, my name is Michael and I started this blog in 2016 to share my DIY journey with you. I love tinkering with electronics, making, fixing, and building - I'm always looking for new projects and exciting DIY ideas. If you do too, grab a cup of coffee and settle in, I'm happy to have you here.


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