Let's Make Robots!

Xbees and rf modules

Hello guys. 

I was thinking about buying a few xbees for my lasertag project but since they're a bit costly i wanted to ask you if it fits my project before buying them.

I'll tell you what i want to to: basically lasertag is a game where there are lots of players that "shoot" at each other with IR pulses. What i wanted to add to it is some sort of "hit feedback", something, be it sound or LED, that tells me whether or not i have succesfully hit my target.

I was planning on having a "server" at the center of the playing field, and an xbee on every player's module. Once a person is hit, his system check the ID of the bullet understanding who shot it, then it sends a "this ID shot me!!111" code to the server xbee, which then sends it back to the ID of the shooter, and finally his system plays a sound.

Couple of questions:

a) is the server really needed or is player to player communication possible? Do consider that number of players might be around 4 per team or more.

b) since these modules cost a lot, could i have a powerful and costly xbee working as the server and cheaper ones on each player's module? Say the server xbee is a 60mW pro and cover 1.5km, does that mean that a player at 1.5km can also have a weaker 500m module or not (as long as he is in range of the powerful server xbee)?

c) is there a better solution to xbees or any tip you'd like to give me?



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There exists 2 modules, the RFM12 is a 5V device, the RFM12B is 3V. Some distributors in Euroland: pollin.de, jeelabs (only RFM12B 868MHz) and tme.eu (only RFM12B). The interface is SPI, for Arduino ready-to-use libraries exists:


One thing to note is the pin spacing on the rfm12's are smaller as you may have noticed, so you'll have to make a custom mount or pin setup for them. example of how I did it using some machine pins... This however may be overkill as I don't think you need to use all of the pins...custom pcb would work as well....

I gotta find myself some more powerful modules i think. Datasheets say these things reach a distance of around 150m. I would need something like 250m to be 100% sure it is gonna be transmitted. Anyone know of something capable of that similar to these modules? (or even different, as long as it is cheap :=) )

Just saw rik's post!

have you had a look at quasars 2.4ghz tranceivers?

the maplin link is here

and the manufacturer link is here

Looks like the range on those is too limited, i'm looking for about 200m.