It all started at the supermarket...

I was queuing at the cash register and I saw that they used a piece of plexiglass with edge leds that changed the colour to indicate if the cash register was opened or closed. I liked the effect of the light around the edge of the plexiglass.

I seemed to remember that I had a piece of plexiglass lying around at home so, as soon as I got there, I wanted to apply that design to something.

As I love electronics, robotics, 3D printing and of course Arduino I thought that I could do some kind of Arduino controlled clock.

After that, and some design, test work and code, I came up with this edge clock.

I'm aware that at the beginning it might be challenging to tell the time but that is what makes it so much fun when some family or friends come home and ask: What is that????

After I explain it, it’s really quite simple:

It uses a common RGB led strip with addressable LEDS (mine in groups of three). It has 12 different groups of LEDS. You can of course change the colour to your liking.

Each line of LEDS is one portion of an hour, so 12 different lines, each one is 5 minutes (except the first one that is o’clock). In addition, the line in different colour tells the hour.

So, imagine line 0, 1, 2 and 3 are on in one colour (white for example) and line 5 is light in green. That means is 5:15, 5 hours because of green line and 5 minutes of each white line add up to 15 min.

If you still have doubts check this video!

After that somewhat long introduction, do you want to print and build one?

Assembling and materials

-Apart from downloading and printing plastic parts, you'll need some electronics and the Arduino Code.

-Check this spreadsheet with links to buy materials. IMPORTANT! Be careful about connecting the correct power supply to your led strip. Connecting a 12v power supply to a 5v led strip WILL BURN THEM ALL!

-You’ll need to do some soldering. Don’t be afraid, it’s not that difficult! If it’s your first time, I’m sure there are hundreds of youtube guides that can help you.

Comments on the code

-IMPORTANT!! DO NOT CONNECT POWER SUPPLY WHILE UPLOADING THE SKETCH FROM ARDUINO IDE. YOU MAY DAMAGE YOUR COMPUTER!! Disconnect power supply and led strip positive cable, then connect USB to Arduino and upload the sketch. When process finishes, you can disconnect USB from your computer and THEN (not before) connect power supply.

-You can change hour and minute colour by modifying red, green and blue colours in the code. If you don’t know what RGB colours are, just ask google.

-My project uses an RTC clock module because using Arduino alone for a clock, even if possible, it’s not a good idea because of the accuracy of Arduino internal clock. That means that, the first time you use it (or when you change RTC module battery) you’ll have to adjust correct time. That is done by uncommenting one line of the code, uploading the sketch to Arduino, commenting that same line again and uploading a second time. You’ll find the commented line in the code.

-Another thing that you may have to change are the pin numbers of the code to match your connections in case you don’t follow my exact diagram.

-And yet another thing to take a look at is the line to adjust the brightness of the led strip strip.setBrightness(240); which you can adjust from 0 (off) to 255 (max).

-Last, bear in mind what kind of led strip you have. My strip controls LEDS in groups of three. If you have a different one you will have to change the code. Download the code from here: Edge clock code