Garage Door Monitor

by Lmsbush

Published on November 19, 2014

Always forgetting to close the garage door? Now you can use the littleBits Cloud module, light sensor, and bright LED to wirelessly check whether your door is up or down! 

How it works:
If the door is open, the light sensor will pick up higher levels of sunlight versus when the door is closed. The cloudBit uses your home's WiFi connection to send this data to the cloud, which can be viewed remotely from any internet-capable electronic device using the Cloud Control interface. When checking the number readout under the "Receive" tab, a high number (closer to 99) means that the sensor is picking up light, indicating that the garage door is open. If the readout shows a low number (closer to 0), this indicates that the sensor is not picking up light, and the door is closed.

But wait, what if it's dark outside?! The sensor won't pick up any light! Never fear, this project has a means for determining the door's position in overcast or night time situations: 

Under the "Send" tab in Cloud Control, adjust the slider to 100 in order to activate the circuit's Bright LED module. If the garage door is closed, the light will bounce off the door and into the light sensor. If you receive a high input reading, the door is indeed closed! 

How To Make It


Begin by activating the cloudBit. Create the following test circuit: USB Power + cloudBit + Bright LED. Plug in the USB Power module to an AC outlet before activation. Now go to and click "Add Device" on the left-hand side. Follow on-screen directions. Disconnect the test circuit when finished.


Calibrate the Threshold:

First, set the sensitivity of the light sensor. Make this circuit: USB power + light sensor + cloudBit. Don't add the threshold to the circuit just yet. Test the light sensor with the garage door open and closed to see what kind of readings you get. They should differ significantly when the door is open versus closed. 

Now, add the threshold after the light sensor. Start with the threshold turned all the way clockwise. On cloud control, the number module should read 00. Slowly start turning the threshold knob counterclockwise, about half way to a full rotation. Now test with the door open and closed. When open, you should see 99 and when closed you should see 00. If you don't, fine tune the threshold by making small adjustments to the knob.


Make the housing for the Garage Door Sensor circuit. Download and print out the housing templates in the littleBits_Garage Sensor.pdf file.


Spray adhesive on the back of the template printouts and place on the foam core. Use the xacto blade to cut out the pieces and holes as indicated.


Apply hot glue to indicated areas on template and place the left, right, and bottom pieces on the indicated areas of the back piece. Make sure the piece with the cutout for the USB cord is on the left side facing you.


Apply hot glue to the separator piece and place at indicated area. This will serve to block off any light from the Bright LED that may interfere with the Light Sensor.


Run the mini USB cord through the hole in the left piece, and plug it into the USB Power module. Make sure the AC plug is connected to the other side of the cord. Continue building the complete circuit: USB Power + Light Sensor (Set to "Light Mode") + Threshold (Turn knob all the way clockwise) + Split + cloudBit + Bright LED.


Attach the Adhesive Shoes to the bottoms of the circuit. Remove protective backings and stick in place, as indicated in the template printouts.


Use the xacto blade to score (gently cut, but not all the way through!) the top piece along the dotted lines as indicated in the template printouts. Apply hot glue to the top of the housing and place the top piece on top. Make sure to scoot the top piece towards the front, as it will act as a "shade" to prevent ambient light from above (like a overhead garage light) from interfering with the light sensor inside the housing.


Use hot glue to attach the shelf bracket to the right side of the housing. See pictures for guidance.


Find a spot along the garage door frame to drill and mount the shelf bracket and sensor housing assembly. Plug the USB Power cord into an extension cord if no AC outlet is nearby. Wait for cloudBit to connect to WiFi.


Go to to test out the sensor. When checking the number readout under the "Receive" tab, a high number (closer to 99) means that the sensor is picking up light, indicating that the garage door is open. If the readout shows a low number (closer to 0), this indicates that the sensor is not picking up light, and the door is closed. Now you're ready to go!

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