Introduction: 8*8 LED Dot Matrix Clock

I got an LED module a few days ago and was thinking about using it for playing Tetris or a Snake game, but I thought that would be lame. So I thought: “why not make a watch?”

As there are only sixty-four dots on one Matrix module, I had to make a smaller dial and figure out a new way to show figures on the screen. Check the video below and guess what time it is.

Beep beep beep! Can you read it? It’s between 11:59 and 12:00.Let me show you how to read it:

Step 1: How to Read

The red dot in the center turns on and off at 1 second intervals continuously, representing seconds.

The blue section represents the hours. Starting at the top, each corner of the square represents 12, 3, 6 and 9.

The orange section represents the quarter of the hour. 0 - 14 is shown in the upper right corner, 15 - 29 is shown in the lower-right corner, 20 - 44 is shown in the lower-left corner and 45 - 59 is shown in the upper left corner.

As you can see in the video, when the triangle is shown in the upper left corner, 14 red LEDs along the outer perimeter are active. That means it’s 59 minutes past the hour. (45 + 14 = 59 minutes).

Then the dots in the upper right corner are brightened. Fifteen red LEDs are active, which represents zero.

I use 15 active red LEDs to represent 0/15 so as to make all dots brightened when 9:15 shows up on the LED module. You can also change the code and use 15 inactive LEDs to represent 0/15.

Confused? This is not intentional, forgive me!

Showing the time on an LED matrix can be tricky, so I used the following system to achieve it:

Eight is an even number, so if the number of activated LEDs that are brightened in any row were an odd number, the overall image shown on the LED module would be asymmetric. I tried as many possible solutions to the problem and then figured out the above way to display the time on the LED matrix.

See below for information about how to make this fancy dot matrix watch:



Connect all the components using the diagram below for reference:

Note: SCL & SDA on Uno is on the left of the digital interface Aref. To find it, you may check the back of UNO first.



I2C address bit

There are three vacant pads on the back of the module. Zero represents off; 1 represents short-term connection.


Once you fully understand the code, you can edit it and display time on the dot matrix watch in a different way. Be creative!

Please see the attachment to find the code


oldegrieze (author)2016-01-14

I like your 8x8 led dot matrix clock very much.
I was inspired to see, if there is a smaller solution, so the clock could be a real wearable watch.
When the leds are SMD's like the watch on it should be possible?

I am not familiar with electronics, but I can use Excel quite well.
I designed a 5x5 clock in excel, look at the 1st pictur.
And I managed to get it working to. So if you like to see it live I will send you the excel

How to read:
The green dots are bi-color leds (green/red)
They represent the hours in a square.
The top row represents 11, 12 and 1 o'clock, the most right column 2, 3 and 4 o'clock
The bottom row from right to left 5, 6 and 7 o'clock and the most left column from down to up 8, 9 and 10 o'clock
The actual hour is red coloured, the rest stays green

The corner dots are white leds
The represent the 10 minute blocks
None of them active means that it is between 00 en 10 minutes past
When the upper left corner is active, it tells you that it is from 10 to 19 minutes past
When the upper right corner is active, it tells you that it is from 20 to 29 minutes past
When the lower left corner is active, it tells you that it is from 30 to 39 minutes past
When the lower right corner is active, it tells you that it is from 40 to 49 minutes past
When all corners are lit, it tells you that it is from 50 to 59 minutes past

The middle section of dots are orange leds
They represent the additional minutes from 0 to 9 in a die format
See the example pictures

I have put the time under the matrices, but they are not part of the clock

If you manage to make such a clock I would like th have one.....


Marcel Maatman (the Netherlands)

oldegrieze (author)oldegrieze2016-01-17

A 7x7 matrix would also be nice, maybe better..........


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