Let's Make Robots!

Atmega Laser Tag - I know it's not a robot


Hi guys,

Way back, about 2-3 years ago, I came here with an idea to make laser tag. You guys were great really helpful however I didn't really have the knowledge, or money, to do it. However recently I was looking at my work and decided to try it again. Now I have the money and most of the knowledge I'm almost there.

As you can probably tell, if you read my original post, I can actually spell and use commas now aswell.

I have designed the system and have now started on the code but I'm second guessing myself and wondering if I have designed the system right. So I have come here to ask the members of 'Let's Make Robots' if I actually got it right this time. The circuit diagram for the gun is attached, the vest is seperate and not complete but works on the same idea.

A few notes about the system;

·         The gun can be disconnected from the player, allowing for players to pickup new guns. This is done through l2c

·         This is my first ever proper electronics project, still, after 2-3 years

·         I have got the atmega328, the multiplexers and the 7 segment displays


Anway thanks to anyone that takes the time to read this, I always enjoy reading projects that are happening here.



Redone Circuit.jpg742.83 KB

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Where do you guys get these maxim LED drivers from? I can't find them on ebay

I don’t know what multiplexers you are using, but you might be better off using some 7-segment LED drivers instead. Then you can get rid of all the transistors.

I have never really used 7 segment LED drivers, do you know of any resources I can look at? Or even a suggestion of a part to use?

CMOS 4026 for example. Just 2 output pins of your micro controller required. One for reset, one for the clock.


u can hook up 8 anodes and 8 cathodes, so up to a 8x8 led matrix, or 8 digit 7 segment displays.
and it does all the multiplexing n stuff for you.

you use it by sending serial commands, and it takes up 3 pins: data in, load and clock.

it also has a data out pin for daisy chaining several of them.

From what I read there is no way to used the MAXI2719 with common anode 7 seg displays. What could I use for common anode displays?

really? i dont see why not, it has 8 anodes and 8 cathodes, why not just wire them the other way around?


You can’t really flip around a 7-segment LED. They come either as common anode or common cathode.

yeah but you can use one anode connection and 8 cathode connections.

it has 8 of each...


I found a common anode system by the same people
They look to be what I'm after.