Go Down

Topic: Best Approach for Clock LED's (Read 1 time) previous topic - next topic

stormchaserjohn

Good day, everyone. I am quite new to Arduino, so I am in need of some recommendations for the correct approach to my project. I plan to make a clock with seven segment LEDs to display hours, minutes and seconds, but also want 60 rectangular LEDs to encircle the numerals, lighting up progressively to mark the seconds.

Would the best solution be to use LED controller chips? I would prefer not to mess about with shift registers, if I can possibly avoid it.

John

funkyguy4000

Check it!

The Max7129 is a great driver for that!

http://lithostech.com/tag/max7129/

and there are plenty of things that it can do and there is plenty of threads about it

Accelerate to 88 miles per hour.

war_spigot

You could charlieplex them(uses 9 pins,you might have flicker if you are lighting up multiple LED's in the circle, and not just one at a time, and will make for some long code(probably)--could be messy), use a 8x8 matrix driver chip(like the MAX7219/7221, uses 3 pins(i think),maybe easy coding(maybe there's a library?)), or use a string of decade counters(Easiest to code, but you'd need either 1-3 pins, some flip-flops, and 8 chips OR 7 pins and 6 chips, if I'm thinking right).  Or get some other multiplexing type chip.  That's a lot of parentheses(another can't hurt).

funkyguy4000

I'm not sure why you wouldnt want to use shift registers.  The 74HC595 shift registers are great and pretty simple to use considering they are about the same difficulty to learn how to use as any other multiplexer or anything else
Accelerate to 88 miles per hour.

Forcebringer

Yes Charlieplexing would be a good idea to get that many LEDs controlled.
You could use the AS1130 http://www.austriamicrosystems.com/led-driver/AS1130 This part can drive 132LEDs As you would need ~32+60=>92 one should be enough.
Also you can get 3 parts for free there.
Also digikey has some info on it:
http://www.digikey.tw/PTM/PTMPartList.page?site=tw&lang=en&ptm=25773

stormchaserjohn

Thanks for all the great suggestions!

One other idea I am considering for the design is to use RGB LED's for the perimeter, and have them light red for seconds, yellow for minutes and green for hours.

I will let you know how everything progresses.

John

war_spigot

Be sure to post it if you complete it, it sounds kind of cool

Go Up