Now, you should be able to test that everything is working. Connect to the Arduino XBee with the X-CTU terminal. Assuming your accelerometer XBee is powered on, you should see lots of data flying by. The data is transmitted in API packets over the XBee's UART, to the FTDI chip, to your computer's USB-serial device. The API packet specification is in the XBee 2.5 manual. Here's some Python that does part of the decoding.
import xbee
Just kidding. Although there is a XBee Python library, it doesn't currently support series 2.5 modules.
Click Here For Source CodeIf you read the spec for API packets, you'll notice I'm glossing over a lot of details. The analog IO bytes are always at the end of the packet. Since we enabled only 3 ADCs, we can just grab the last three shorts.
Finally, here is a picture of my breadboarded version (with voltage dividers) of this. It works great. I'm currently working on a PCB so that the whole thing is compact enough to be wearable.
Some further notes:
- The chip antenna versions are pretty directional. There's a lot of interference in my apartment (a long story for another post) and I don't get very good range. I plan to buy some more 60mW XBee Pros with wire antennas in the future. I'd recommend getting the high power ones unless you're really concerned about battery life. I wish I had.
- Digi's tech support is really pretty great. I had some trouble flashing one of my XBee's and they got in contact with me on the same business day.
- Unfortunately, the XBee only has 4 ADCs. If it had one more, you could add a pitch and roll gyro to the mix without an additional MCU. Oh, well.
- The XBee pin spacing doesn't match standard breadboards. But, the XBee Explorer USB doubles as an XBee breakout board for breadboard designs (as seen in the photo above) if you solder on some additional headers.
