Arduino Refrigerator Alert System

This is a work in progress. My 11 yr old son and I are working on this together. The idea came about due to the fact that we have 5 kids in our house. The refrigerator is popular place, and the door gets left open often.

I feel this is a good project to work on because we saw a problem and have been designing a solution to fix it. We are learning about the Arduino together which has been so much fun.

We are using a 8x8 LED board and Bare Bones Board from We have set up an LDR to sense when the light is on inside the refrigerator. If the light is on, the LED board is activated and will scroll the text "The Door Is Open. Please Close Door".

Here is our project page with photos:

Here is a little YouTube Video of the prototype

To Do:

We have a .WAV file that I created with a text to speech program that will also say "The Door Is Open, Please Close Door". We haven't figured out how to make that play yet. The alternate would be to just make a simple beeping noise. If someone can point me in the direction for a simple beeping sound code I would appreciate it.

System housing... I think we are going to use some Plexi-glass and make a container that can mount on the outside of the refrigerator door.

I don't know anything about playing Wavs but there is a wave shield available from adafruit. I don't own one or know anything about it though.

You could use a piezo buzzer: I have used this code and it works well! A piezo would be small and effective if you bond the element to a small piece of sheet metal.

When you get to the part of having the LDR trigger the interrupt, take a look at mine.

I found that when the LDR was crossing the threshold from high to low. it triggered the interrupt a lot. I fixed this by doing several digitalReads within the interrupt to see if the change was valid.

Hope you guys have fun!

Hey Daniel, I was actually checking out your site last night. Thanks for sharing your code. I am going to take a look at it.

Y4M4, yeah I was thinking about the Adafruit WAV shield also and wondered if that would work. I think we are going to try the Play Melody tone first with a Piezo. It would be more cost effect since this is more of a fun project for us to learn from and solve a problem. Just having the tones would get the persons attention.

The play melody tone works very well. I edited the notes to get an annoying alarm sound.

I'm glad the piezo worked out for you guys.

I stumbled across your blog and it looks like you two are living up to your domain name. I like the site a lot; especially the step-by-step, THIS WIRE GOES HERE posts which is exactly the kind of article we need more of on the internet.

Glad you liked our blog. It has been a really fun project to work on.