Sensor pack prototype assembly

Step-by-step of building the first sensor pack protoboard with basic temperature, humidity and pressure sensors, using an Arduino Fio.

Parts list:

  • Radio shack perf board – Catalog #: 276-148
  • Arduino Fio – Arduino board, with XBee socket and built-in battery charger
  • SHT15 – Temperature and humidity sensor, on a break-out board
  • SCP1000 – Pressure and temperature sensor, on a break-out board
  • 22GA wire
  • XBee – Easy to use, and affordable wireless boards. I use both the low-power and the extended range versions, with chip antennas, and with wire antennas. You can mix-and-match to match your transmission distance needs.
  • Solar panel. Still looking for the optimal size for my location. This one generates more power than I need.
  • 2000mAh LiPoly battery – With my current power-saving code, and 10 minute transmission settings, I’m getting around 200 hours of power from a fully charged battery.

The solar/LiPoly combination is overkill for this setup, but since I’ll be adding wind/rain sensors to the next iteration, I’m going to stay with the overrated solar cell/battery combination. You could easily get by with a 1000mAh battery and/or a smaller solar cell. I’ve tried both, and got acceptable performance in an area with good sun.

First, I put a jumper between DTR for the XBee and Arduino pin #4, which I use to put the XBee into sleep mode between transmissions. Since the sensor pack only transmits data, it only needs to be powered up when it sends a data packet.

I also soldered headers onto all the Arduino pins, since I’ll be using more of them in future sensor pack versions. For the basic version, only pins 4-7 (SHT15) and 10-13 (SCP1000 via the SPI library) are being used.

On the left side of the board, you can see the 2-pin 90 degree header soldering into the 5V input for charging the battery. This was to make it easy to connect, as well as change the solar panel.

Now for the ugly part. Using a small project board, I soldered female headers in for the sensor break-out boards and the Arduino (I only soldered a header for one side of the Arduino, since the other side is currently unused).

Then, I soldered wires in to the rows next to the headers, bent them over to bridge the gap, and create a good electrical connection.

Finally, I routed the wires to the appropriate destinations on the Arduino header. It’s a little extra ugly, because I screwed up and reversed the pins for a header, then had to remove and re-solder the wires.

And finally, after testing all the connections for continuity and fixing any unintentional crossed connections, simply plug the Arduino and break-out boards in their spots on the project board.

Then, to complete the project, simply plug in the battery and solar cell (which I cut the power wire, and attached a 2-pin female socket to) to the Ardino Fio.