Arduino Powered Binary Clock

Step 2 8421 Binary and 24 Hour Time

First, lets take a look at how to understand the 8421 Binary system.  Your clock is going to have two columns for the "hours" and two columns for the "minutes".

We are using a 24 hour time system.

With that said, if it were 8 AM, the time is 0800 hours and if it were 8 PM, the time would be read as 20:00 hours.  In US Army basic training, when you first learn this time system, they taught us to just count backwards by 2 for PM times. So for example, if I was told to be in formation by 2100 hours. In my head I was thinking 2100 - so 1, 0, 9 and knew they meant 9 PM.

Or if we were off work  at 1630 hours, in my head I was thinking 1630 - so 6, 5, 4 and knew the day was over at 4:30 PM. I hope that makes sense, I felt the need to explain for anyone who is not use to telling time with this method.

Looking at the 8421 Binary Example image, in the first column of the hour leds, if the first led was lit up, its value would be worth 1 and in the second column if the 4th(top) led was lit, its value would be worth 8. Therefore you would have 18.

Now with the minute leds, lets say the first column has the third led and the first led lit up. This value would be 4+1=5. The second column, third led is lit up would give a value of 4. So together you would have 54.

The overall time would read as 18:54 which would be 6:54 PM

Look at the second image example. The time is 21:37

Examples Images from Daniel Andrade