New Project: GSM Motion Sensor

My first project will be a motion sensor that will alert me thousands of miles away if it's triggered.  There's actually a really good reason why this is the first thing I'm making.

When I was packing up to move to France, I rented a storage unit.  When I was signing the lease, I overheard the manager talking to a new employee, explaining that theft occasionally happens there and all the stuff she had to do to be vigilant.  That made me think: if someone broke into my storage unit then put a new lock on, it would be months before I knew about it.  The video tapes and access records would probably be long gone.  So, I set out to make something that would let me know as soon as someone entered my storage unit.  

The requirements are simple:

• It must run on a battery for up to 12 months
• It must not rely on WiFi
• It must be relatively cheap

I couldn't find any product that combined these three.  There are GSM game cameras ([1], [2]), but they're very expensive and I couldn't find anything about their battery life.  I considered using my Raspberry Pi with a GSM shield, but the power draw on a Raspberry Pi would kill even the one of the largest USB battery packs you can buy in a week (40000 mAh / 230 mAh for an idle Pi = 174 hours = 7.25 days).

I know a passive infrared (PIR) sensor draws very little power – on the order of 5 µA.  And I know the MSP430 from TI has an ultra low power draw in sleep mode.  Plus, you can get a SIM300 or SIM900 GSM chip that supports serial or SPI communication and can sleep using very little power.

So, it seems like I've got a basic plan sketched out: An MSP430 that will be triggered by a PIR sensor with a SIM300 or SIM900.  I was able to find a MSP430 combined with PIR sensor, so that would eliminate all of the analog electronics.  I bought that, then started asking for advice.

I asked on Facebook, and I got some helpful feedback from one of my old coworkers, Eric, and my wife's cousin, John.  Plus a not-so-helpful comment from my mom.

After I ordered everything with next-day shipping so I could bring it to France, I started thinking if I was getting in over my head.  Is this too big of a first hardware project?  Did I just waste a bunch of money on projects I'm not going to finish?



Next up: GSM Motion Sensor: Everything arrives.