Introduction: Rangefinder for Garage Parking With Arduino

About: I like to develop android apps and electronics devices that can be controlled by that apps. My first pc was a commodore VIC20 hacked to program Eprom chips :)

This simple project will help you park your car in the garage by displaying the distance from objects in front of your car's bumper.
A 'Stop' message will tell you when it's time to stop.
The project is based on the usuals HC-SR04 or Parallax Ping))) (tm) ultrasonic rangefinders and an Arduino board.
I used the Leonardo but it should work on any other original or compatible board.

For the display I chose a matrix version for its size and for aesthetic reasons.

Step 1: What You Need...

To build this project you need:

  1. An Arduino board:
    An original or compatible board should work as the code doesn't make use of specialized pins/function.
    You can find it everywhere on the internet or maybe you have one unused in a drawer in your lab.
  2. An HC-SR04 or Parallax Ping))) ultrasonic rangefinder:
    They are commonly used with Arduino projects so, probably, you already have it.
    Anyway here are some links:
    - Parallax Ping))) on Parallax
    - HC-SR04 on Sparkfun
    - Parallax Ping)) on Pololu
    - HC-SR04 search result from Ebay
  3. The Four matrix display:
    I bought it from IOTMODULES on Ebay: 4 Way MAX7219 DOT MATRIX
    In case the link doesn't work try contact them on their Ebay store.
  4. Soldering skills, of course :)

Step 2: Build the Project...

Download the arduinorangefinder.pdf schematic diagram.
You can find attached also the HC-SR04 pdf and the ping))) pdf, only for your reference.

The electronic diagram is very simple, follow it exactly.
I suggest to extend the wirings for the display and sensor of about 1 meter (see image1) so you can place them more easily later.

In the image2 you can see how to solder the power supply pins for the display and sensor: +5V from the display and Vcc from the sensor needs to be soldered togheter.
Every other pin must have its own terminal.

Image5 is the Ping))) version of the project.

Go to the next step when ready...

Step 3: Arduino Code...

It's time to work on the Arduino side.

Download the attached library and install it from the IDE (sketch->import library).

Now unzip and load the MeasureDistanceV200.ino sketch and let's look into it.
There are several lines you can edit:

1) The Matrix display type:
the supplied library supports 4 matrix display type so it shuold work with most displays in the market. Just uncomment one define at a time and upload the code to Arduino to see if it match your display.

2) The sensor type:
uncomment only the line that match your sensor.

3) Choose your preferred measuring unit from centimeters or inches:
uncomment only the right one, a warning has been set in the conditional compilation, it will show you what you have chosen.

Now set the distances as you prefer, you can modify them later when the project will be in place.

Upload the code and check if all works.
If you get trouble please double check wirings and connections.

Update 2019/03/30 - The code has been updated:
> New matrix display library, it supports 4 display type (a lot of documentation inside the library)
Credits to majicdesigns

Update 2019/01/10 - The code has been updated:
> Added the possibility to choose the measuring unit from centimeters or inches

Update 2017/12/30 - The code has been updated:
> Turn off the display when standstill at STOP distance for more than 10 seconds!

Step 4: The Project at Work...

Measure the height of the most prominent part of the bumper of your car from the floor.
Attach the sensor close to the wall, to the height you measured.

I used a polystyrene foam sheet in which I made a slot for the sensor (see image).

Now place the display so you can see it from your car.

Try to enter by car and check the distances, adjust them in the Arduino code and reupload it if need.