Advice on first project

Hello everyone,

I hope this is the right forum to post this area in the forum to post this to.

I'm starting a project to create a wireless race timer and I want to make sure I'm getting hardware that is compatible because I was looking in the comments section and someone mentioned it might not be.

Here's the setup.

I wireless transmitter for a start timer, a wireless transmitter for stop timer, and a receiver to connect to a pc.

Here is my hardware list

2 arduino unos http://www.sparkfun.com/products/9950
2 xbee shields SparkFun XBee Shield - WRL-12847 - SparkFun Electronics
3 xbee 60mW http://www.sparkfun.com/products/8690
1 explorer board http://www.sparkfun.com/products/8687

Is this hardware compatible? Arduino was suggested elsewhere, but I want to make sure it'll work together before I buy it. I know almost nothing about electronics. I studied computer science and we don't really get training in electronics.

Thanks in advance,
-Nate

edit: 3 xbee

You have two xBee modules, and 3 places to "mount" them (the two shields and the explorer board). I am not exactly sure how you expect to use them.(OP updated his list)

If you want to have both units wireless, I believe you need an individual receiver for each unit (can someone else please varify this? I have never tried this, but the projects I am familiar with which use xBee work this way.).

If you only want one of the two units wireless, you can simply connect the second arduino to your computer via usb and you have no need for the explorer board.

You have two xBee modules, and 3 places to "mount" them

The list in the post prior to yours show 3 XBees.

OP: What range are you needing from the XBees? What kind of race are you timing? Indoors or outdoors?

What will the Arduino's be doing? You may not need any Arduinos (or shields) at all. The XBees have some digital IO pins, like the Arduino, and can read, and transmit, switch info directly.

Hello,

Thanks for your replies. Here's more info about the race:

Its an outdoor race and the range is a couple hundred yards. I is also a winter race, so I need to be able to store the electronics in a waterproof container (like a pvc pipe) and still be able to transmit. I chose the 60mW because the range would be more than enough (even in a waterproof containter) and I think you want some extra range as opposed to edge of the xbee's range.

I was thinking I would use an uno, shield and xbee at the start to send out a "start timer" message when a wire was tripped. (Maybe using a door alarm or something). The second uno/shield/xbee would send out a "stop timer" message. Then, the explorer/xbee would be a USB interface to connect to a pc and receive the messages.

What will the Arduino's be doing? You may not need any Arduinos (or shields) at all. The XBees have some digital IO pins, like the Arduino, and can read, and transmit, switch info directly.

The Arduinos are for controlling the message sending. I thought it would be easier to program the arduinos to send the messages because my background is in computer science and not electronics. However, if you think I could easily do it with pins, I'm open to that.

Thanks,
Nate

I thought it would be easier to program the arduinos to send the messages because my background is in computer science and not electronics.

Then I'd recommend keeping the Arduinos in the mix. You can always find another use for them when the race is over.

So will this setup work, the reason I ask is because there is a comment on SparkFun XBee Shield - WRL-12847 - SparkFun Electronics that suggests that the uno will no work with the shield.

Both the UNO and the Duemilanove use the same ATMega328 chip, but different USB to serial chips. Since the USB to serial chip is not involved in the shield to Arduino communication, I can see no reason why the XBee shield would not work with a UNO. It works fine on my Duemilanove.

Most of the issues seem to be getting the XBees to actually communicate with each other, not with getting them to communicate with the Arduinos.