I'm running into a problem with a SparkFun XBee Shield (WRL-10854) when used with a RedBoard (DEV-10908) (Arduino Uno compatible) where it doesn't receive the signal being sent to it. When the same shield is connected to a regular Arduino Uno R3 it receives the signal. When either the RedBoard or the Arduino are connected to the XBee while it is on a breadboard they work correctly. But when the XBee is moved to the Shield the Arduino works, but the RedBoard doesn't. Does anyone know what this problem could be or how to debug it? (I'm aware of the UART/DLINE switch and it is in the right position.)
Also, I have a connection indicator LED hooked up to pin 6 (Received Signal Strength (RSS)) of the sending XBee and it is turning on even when the RedBoard is being used. This means that there is a connection, but somehow the RedBoard isn't receiving it. Similarly, an LED hooked up to pin 6 of the receiving XBee also lights up.
One strange thing I found is that if I connect a wire to the TX pin of the RedBoard and going through a LED to ground the RedBoard starts receiving the signal, but it is corrupted, that is there are garbage characters mixed in with the correct characters.
edit After switching a different ATMega328P onto the RedBoard, this problem goes away. So this problem must be due to some differences in the settings on the pre-programmed ATMega328P from SparkFun.