Can you turn a NFC tag off?

Seemingly stupid question, but I would like to know if there is some way to turn an NFC tag off.

Basically, I'm helping a friend with a game of lazer tag he's trying to throw together with some scrap parts, and one of the ideas was a health pack. To try and balance things, we want the health pack to only work X amount of times, with a Y cooldown between uses. My original thought for this is to just stick a micro-controller inside the health pack that would control a NFC tag that can be turned off an on per parameters set on the controller. The person wanting to use the pack would just pick it up, and stick it to there chest to use it. Once used, the tag goes off for the cooldown. 

Alternately, if there was some way to re-write the tag from an arduino or similar platform, that would work just as well (maybe even better!)

thanks in advance! 

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Don't bother. Just record the tag id. When its "used up", that tag ID can't be used again.

DoctorWoo (author)  steveastrouk2 years ago

Sounds like your talking about networking the vests together. Which, oddly enough, we though of doing something like that just a few minutes before I checked for answers! Happen to know of a realativly cheap way to network micro-controllers together with a large range?

Use Zigbee, its not fast, but its ideal for this, because it can create meshes between units, and a unit that can't talk directly to a distant one, can send a message to the nearest and bounce it on....

Alteranively, your health pack could be an IR transmitter, like a TV remote. Press the button on it more than X times, and it stops working for an hour or whatever.

24 years ago I developed a commercial laser tag game, actually shooting with a diode laser, when they weren't cheap ! I used DTMF phone chips to modulate the laser, and receive the signal, on conventional solar cells. I can post you a picture of the guns. It worked, even in daylight. There was a "master gun", which the gamecontroller wiped over the player to reset the game, but RF would be better these days.

Be happy to advise you, as you move on. I'm moving to the USA at the end of the month.

DoctorWoo (author)  steveastrouk2 years ago

Really? I had no idea they could do that! That's handy to know for some other projects. Can you limit the bounce? I might look to do this is an open field, and it's be nice to be able to limit how far people can get from "base"

As for the IR option: I feel kinda stupid for not thinking of that to begin with. What with the fact that I'll be using some sort of IR setup for the guns and tag system as is.

And that sounds awesome! I've seen diode laser and briefly toyed with one a friend had. Stupid question: but aren't they dangerous? Or are they just as dangerous as cheap laser you get from the dollar store? And I do like the idea of a master gun! But as you said, RF would be better (and the way I'll be going) so I think I'll make some sort of master controller running off of a RPi or similar setup.

And where in the states are you looking to live?

I think you can limit the bounce.

No, the dime store lasers are all you need. You get pinpoint shooting then, like a real gun. You can use a class I or class II laser with no problems at all.

State College Pennsylvania.


bwrussell2 years ago

Do you have a NFC tag or chip?

NFC tags are passive, they simply store information. They are powered by induction from a NFC reader chip. The only way to alter their state is with a NFC chip. These are cheap.

NFC chips are actively controlled and powered by some sort of processor. These can read or write data and can output whatever the processor sends. These are expensive.

If you had a chip you should be able to use your microcontroller idea. If you have a tag then its a little more complicated. I see two ways the entire system could be working and that will determine exactly how the packs would behave.

If everyone's suits are talking to each other and their is some sort of master system watching all the players then it could track who, when, and how many times a health pack was used. Just like steveastrouk said, each pack would have a unique ID and could essentially turn it on ad off by ignoring it when it's in cooldown.

The alternative is that there is no master system, each players suit tracks everything itself. In this case you use the same method except that the pack would have an individual cooldown for each player. i.e. If player A uses pack 1 then he can't use it again for x minutes but player B could use it immediately afterward.

How ever it gets implemented you should probably limit the number of times an individual player can use a pack to keep them from just taking it with them. Either that or tether it in place, somewhere relatively exposed to prevent camping, so it can't be moved.

DoctorWoo (author)  bwrussell2 years ago

He has readers, I have tags (not chips).

I kinda figured they were powered off induction (just due to the coils in them).

Out of curiosity...how expensive is expensive when you talk about the chips? Chances are there is no way we'd use them, as this is just a "spend little to no money" pet project.

As for the networking idea, as I said to steveastoruck answer, my mate and I had the same idea a few moments ago (it came around from the idea of seeing about making a 'team captain' that can see over his team). Long run, I think this would work better, as we can add more features to the setup. My only concern is how to setup such a network, and the range of it.

As for the implantation of the pack, it will be nailed down somewhere! Not to be rude, but my group of friends (myself included) aren't what you would call "active" and we'd camp out next to things like this with not a care in the world. If we do go down the network path, I might change it up a bit and set up a base for ammo and health that can be "upgraded". All tenative, at this time.