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[on:]

Hi everybody,
i've been around Arduino for a long time now, and now I have decided to do my first (TA-DAA!!!) Arduino project. I know what i need, more or less, but I'm looking for suggestions. Very very welcommed!
My project will be about a couple of bracelet capable of detecting XYZ movements.
I want it to be as small (and wireless) as possible.
These are my first cooking list's items:

- 2 Arduino Mini
- 2 Triple Axis Accelerometer (i was thinking about "Breakout - ADXL345")
- 2 Xbee (what kind??)

Do I miss something?
Would you suggest a different approach, or items?
I'm also trying to figure out how to deal with batteries... i'd like to have amsll/flat ones, is that possible?
Thanks, thanks a lot.
I'm looking forward to start my first project!

[Reply #1 on:]

- 2 Xbee (what kind??)

Where are you going to send the data? What are you going to do with the data?

How will the bracelets be attached? Loosely, like a charm bracelet, or tighter, like a watch band?

[Reply #2 on:]

well... i'm going to send data to a computer with MAX/MSP, so that i use those values to make some music.
The bracelets will be attached as tight as possible, much like a "tennis foam bracelet" (it's obvious I don't know the propoper english word! ahah. sorry for that, but i'm sure you'll figure out)
thanks much

[Reply #3 on:]

So you need 3 xbees - one sender on each wrist, and one as the receiver.

Does the receiver need to communicate with the senders? In other words, is there any data to send back to the wristbands? I can't imagine that there would be.

If not, then the Series 1 xbees are the way to go. They come in two power levels - regular and Pro. Better battery life with the regular version; better range with the Pro version.

They come with 3 different antenna styles. Chip antennas don't provide much range, but they are flat on the board. Wire antennas provide better range, but stick up 2 - 3 cms. External antennas provide the greatest range, but are the largest.

[Reply #4 on:]

great! thanks much!
no, i don't need feedback from the computer-based Xbee to the wristbands (i got the word!).

Sooo... this should be my final (if i can't optimize it anymore) shopping list:

- 2 LilyPad XBee (for the wristbands)
- 1 arduino (with the receiver Xbee attached on it: aren't there other ways?)
- 3 XBee 1mW with "chip" Antenna (just need 5-10 meters range; they are 2 for the wristbands and 1 to receive both)
- 2 LilyPad Power Supply
- 2 LilyPad Accelerometer ADXL335

I think that's all. no?

[Reply #5 on:]

You don't need an Arduino connected to the computer, with a xbee on it. You can connect one of these, instead:

http://www.sparkfun.com/commerce/product_info.php?products_id=8687

[Reply #6 on:]

Word of warning: working out movement from just an accelerometer is a bit tricky. They pick up gravity as well as your movements, which will vary between axes depending upon how the accelerometer is tilted. With no extra reference (compass, gyro) it's not necessarily possible to disambiguate the two.

Sounds like a fun project though, good luck!

[Reply #7 on:]

thanks much RaygunGothic!
At this point, I guess, I'll try to attach a gyro as well... you are right...
One other thing... i see Xbee + Arduino is gonna be very big for the intended idea. Even in the Lilypad version.
I am thinking about Arduino Mini + BlueTooth Mate... Do you think bluetooth have too much latency for some ambient music project (i mean... it's not a techno with very high beats per minute)?
again, thank you for your reply

[Reply #8 on:]

Don't let me put you off! It sounds like a good project. I just wanted to say "be prepared for a snag"... I made a mistake there myself :-)

My recommendation would be to try to get to grips with components in small doses before trying to integrate too much together, but I'm quite cautious like that (or I am now!)