XBee Doorbell Lab

For Rob Faludi's Sensitive Buildings class, we were told to make a wireless doorbell using two XBee radios. Since my router and coordinator radios were already set up from the previous chat lab, I was expecting this assignment to be a plug-and-chug exercise (we were even given the code!) However, when the project didn't work I embarked on an epic troubleshooting journey. I tested everything from contact continuity, to swapping XBees, recalibrating them, an even doing the entire chat lab over again.

I had it narrowed down to an issue between the Router Xbee's serial communication with its attached Arduino. The indicator LED on pin six would light up when I pushed the coordinator's button, but the test LED for my "bell" coming from the digital pin on the Arduino refused to light up. I even ran a "hello world" sketch just to make sure the arduino was functioning properly with the LED. Oddly enough, once I pulled the indicator LED off pin six, the Arduino's LED started working! It was dumb luck that I discovered this, and as far as I know, my classmates did not have the same issue. I'm now wondering if this is a documented bug or not. I'm meeting Rob tomorrow and will update this post once we've taken a look at it.

UPDATE! Somehow the solder joint on the power pin of the XBee breakout board broke, but there was still a thin connection being made to the XBee. It was getting just enough current to either light the indicator LED, or send the serial communication to Arduino, but not both at the same time, which explains the strange problem I was getting. Once all the solder points were warmed up everything then worked like a charm.