Picture of XBee PCBs

During the course of this week, I have received my XBee PCBs (right) and started playing with them!

First of all, I’d like to say thanks to the folks at Seeed Studio / Fusion PCB whose service I used to fab these boards. I went for the slightly more expensive ENIG finish on these, but they were still very reasonably priced and have come out very well indeed. I would definitely use them again.

So anyway, after a quick order for some extra TC2117 regulators that I found I ran out of, and a fistful of LEDs and that sort of thing, I built two backpacks up complete with XBee modules and set out to get them to talk. This was my first foray into the world of XBee / ZigBee so was a very interesting process!

XBee Backpacks on my two Raspberry Pis

After upgrading the firmware on the modules using X-CTU and my trusty FTDI cable (with the modules on the backpacks), I set one up as a coordinator and connected them up (using the AT commands) so that they had a sort of serial session open between them. I then put jumper wires across the TX/RX lines on the two FTDI connectors on one module, and I had a wireless serial console to my other RPi!

 Features

Populated backpack – front

Let’s talk about what my backpacks can do:

• Use a Digi XBee ZB SMT with your Raspberry Pi, thus joining your Raspberry Pi to a ZigBee network – either as a coordinator or as a router.
• You could also use a “normal” XBee module (or compatibles) with the standard headers also included.
• Communicate with the module using SPI (ZB SMT only) or TTL serial (after bridging two solder jumpers).
• Two FTDI compatible headers are included, one for the Raspberry Pi’s serial console and one for the XBee module. Fully compatible with X-CTU for configuration and firmware upgrades.
• Three LEDs are included for OK, Association and RSSI.
• Solder jumpers for configuration:
  • SPI chip select line (CE0 or CE1 or none)
  • Interrupt line (GPIO4 or GPIO17)
  • DTR / Sleep Request line (GPIO24 or GPIO25)
• Features an on-board 3.3V regulator so the Raspberry Pi’s own limited 3.3V supply is not used. Alternatively, a solder jumper can bridge the connection to use the Pi’s internal supply.
• If you use a stacking connector (recommended), you still have access to all the pins on the GPIO header for things like I2C or another SPI device!

What next?

Populated backpack – rear

Well the hardware is done and appears to work quite nicely. Next, we need a software stack to actually use the ZigBee network in more ways than just a dumb serial console. There is a libxbee that may be useful, though I feel I may end up writing my own library and client/server architecture for use with SPI and UART ZigBee XBees and multiple client programs.

Onwards and upwards!