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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learning the use of some manner of schematic drawing software might be useful. Your schematic seems pretty decent with respect to the icons, etc. I just can't get the whole thing on one page and see it at the same time.

Fritzing might be easy to pick up on.

I only mention schematic software because, while your drawing may be accurate, it is difficult to follow due to it being a scan of a pen(cil) and paper drawing.

I completely understand, I was worried the sketch may have been to hard to read but wasn't sure how to improve it. I have been looking for a schematic software package but everything I tried was very hard to work with. Thanks for recommending me one. I'll go play with it.

another one u could try is TinyCAD.

anyhoo can u explain more about how this system works?

like why are the guns connected to the player?



I did the circuit in Fritzing and it is attached to the original post now. The unlabled IC's are '4051 Multiplexers'

The system comes in two parts. The first part being the gun itself, this has a firing rate, clip size and amount of clips. All it does is shoot IR signals with a damage value, a team and a ID. The team and ID is set through the l2c port. However the gun will not fire unless a vest, the second part, is connected.

The vest is the player. This has the IR sensors on it and displays the health. It also sets the guns team and ID when it is connected. The vest gets this info from the serial port before the game. When the vest is dead it stops the gun from being able to fire aswell.

The party peice of this system is that it allows a player to disconnect his current gun and pick a new one up, plug it in and continue playing as if nothing had changed. When the player is not connect to a gun they can still recieve hits and lose health.

I hope this explains the system a bit more. I also want to thank you all for responding so fast!

I have some questions. :)

The 3 LEDs on pin D3, what are they for?

On pin D4 you have an IR LED, was that meant to be an IR phototransistor or IR photodiode?

What is the 25 pin connector supposed to be used for?

What are the two connectors with the USB symbol in them?

If you are planning on making PCBs for these circuits, you may want to consider moving your pin D7 and D8 connections to the other side of the chip to two of the three open PWM pins at the bottom of the chip for easier routing.

I love questions!

1. The 3 LEDs are for a muzzle flash

2. It's an Infered LED, for sending IR signals. http://www.ebay.com/itm/160833338024?_trksid=p5197.c0.m619#ht_1865wt_957

3.  Pin 25 is not connected to anything, it is an analog pin however.

4. They are for the l2c connection between the gun and the players vest. There is a possiblitly that the other one will be used for some form of health station. The connector could be a USB header or 3.5mm audio jack.

That is a good idea, I'm not up to the PCB stage yet but if this circuit works and I can get a breadboard prototype working then I will move to a custom PCB

Re: question 3

I was asking about the 25 pin connector at the top of your schematic.

That is the serial connector, I won't be using a 25 pin version.

So did I design it right?

I redid the calculations, they are all right, but still feel like something is wrong with it.

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.