I was trying to get an XBEE S1 pair to work together with an Arduino Pro Mini (5V), or an Arduino Trinket (3.3V). It was working with an Uno, and a SparkFun XBEE shield, but I was unable to find a shield to go with the smaller-size Arduinos.
I never did get the XBEE communicating in transparent mode with the small Arduinos, and I was wondering if it had to do with the shield doing some mojo for the 5V Uno with data pin voltage conversion, since the XBEE wants 3V, not 5V. Since I didn't have a shield for the smaller Pro Min 5V, that may have been a problem. No idea why I could never get it working with the 3V Trinket.
I have just joined the forum, and wanted to search around for info on using XBEEs with tiny Arduino packages. If anyone has been through this, please share any tips you have.