Environmental Sensor Pack, Version 1

By kaydub


After I’ve got this all working well with the right hardware and software, I’ll be putting together a kit of all the components to build your own in the soon-to-be-opening store! I plan to have several versions of this sensor pack, a basic temperature/pressure unit, a more complete weather station, and a few other kits as well.

Using a batch of parts from SparkFun I set out to create a basic, but adaptable environmental sensor that could sit outside and be portable. The initial parts I put together were:

Wireless:

  • XBee Explorer Regulated
  • XBee 1mW Chip Antenna

Sensors

  • MEMs Barometric Pressure Sensor – SCP1000 Breakout
  • Humidity and Temperature Sensor – SHT15 Breakout

Charging:

  • Solar Cell Small – 0.45W
  • Polymer Lithium Ion Batteries – 1000mAh
  • LiPoly Charger – Single Cell 3.7-7V Input

Which I attached to an Arduino duemilanove and a simple protype shield:

Using code I found from around the net, I got the SP1000 and the SHT15 talking, and thanks to both the Making things talk book, and some more web research, not only got the XBee’s chatting, but got the remote XBee going to sleep between transmissions.

Next stage was to use a 3.3v Arduino board, which would work better with the LiPo battery, since the  duemilanove expects 5V+ in, and was getting 4V, degrading over time. Without the voltage reduction circuitry, I’d be able to get everything humming along for much longer before the voltage dropped enough for things to start shutting off. Here’s a fuzzy picture of that setup on a breadboard:

This worked quite well, except I couldn’t get the software reset to work on the Arduino Pro Mini, but I probably screwed up when I soldered the bottom connector. I can still download sketches to it, I just have to hit the reset button manually when I do. So, I made it a breadboard Arduino. I’m going to experiment with a few other Arduino boards as well, there are several nice compact boards to try out.

Currently, I’m working on power management, battery sizing, and simple logging/display software on the receiving end. I’ll update as the project progresses!

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