While I’m logging data and waiting for it to become substantial enough to test another project with, I thought it would be nice to kill the time and start building some new sensors: motion, temperature and light.
My goal is to monitor the complete second floor. For the 3 bedrooms I want to monitor motion, temperature and light. The passage will only require motion and light, while measuring the humidity in the bathroom would be nice too.
So, for that I need the following:
- 5 * motion;
- 4 * temperature;
- 5 * light;
- 1 * humidity.
OK; the amount of sensors I want to use is a bit too much for a single JeeNode I guess. Maybe 2 JeeNodes will suffice? I didn’t do any math on this yet, but I don’t think a single JeeNode can do the job all on its own. 2 JeeNodes maybe, cause the temperature sensors can be on a single 1-Wire bus, so those sensors won’t use up much ports on the JeeNode; and maybe I can use an Analog Plug to measure the LDRs? We’ll see. But for now, I assume I’ll need more than 1 JeeNode. However, I don’t like to spend an XBee module on each of those JeeNodes, cause I want to keep it relatively low cost. Yeah I know, there are cheaper alternatives for XBee..
But wait, I’ve still got an Arduino Fio; I’ve bought it sometime in January, not for a specific purpose but just to have a look at it, and I never found a good use for it yet. This Fio is also based on the ATmega328P and runs at 3.3V and 8 MHz. And it also has an XBee socket and USB connector. And it’s getting old, gathering dust on the shelf…
Now why don’t I use this Fio as a ‘hub’, or ‘central node’? It shouldn’t be too hard to make the (1,2,..) JeeNodes talk to this Arduino Fio over a few wires and use the Fio to transmit all the sensor values to the Zigbee coordinator; now that would be nice! I could power this Fio with a small USB power adapter and run a few wires (for power and serial connection) to the JeeNodes. Maybe I could just as easily use 1 JeeNode per room; this leaves enough ports available for future expansion… well, let’s think this one over for some time!