Raspberry Pi Home Datalogger

I've wanted to do something like this since I first started playing with microprocessors.  The idea of an inexpensive, distributed sensor network throughout the house is really cool.  In Hollywood we always see someone sitting at their computer console accessing their security system.  It's typically a wire-frame display with sensors all over the place.  They're getting all kinds of data, and even providing the occasional remote output (displays, lights or sirens, etc).

The $35 Raspberry Pi is almost the ideal basis for this kind of sensor network.  It runs a (relatively) well developed Linux distribution.  It has two USB ports, runs on 5v, sports an ethernet port, and will support almost any video display out there.  More importantly, it has several exposed general purpose I/O pins and supports I2C.

I'm using Lady Ada's Occidentalis distro.  So far it has been incredibly stable (though it swaps between video outputs if I cut power to the system).  I'm using this distro because there are examples using Python to access the various GPIO's and the I2C.

My previous post detailed some of my earlier experiments with the system.  Since then, I have worked on building a series of programs to access a BMP085 board attached to the I2C bus.  I haven't done much with Python in quite awhile, so I'm fairly rusty and lacking a definite style.

I finished a series of programs last night that check the sensor, log the sensor data to a logfile and update a webpage, and a simple program to automate the whole process.  Currently I've got the sensor being checked and logged every minute.  The logger program is using the Python Logging module.  I'm recording the event level (I'm generating a warning if the temperature reaches 30c), the epoch time (to facilitate graphing later), and the temperature and pressure (I don't care about the altitude).  Using epoch time versus Python's asctime also saves some memory.  The log files are between 1.8 and 18 megabytes per day (one measurement per minute).  This yields recordings between 50-500 days per gigabyte.  I'm not sure why there is such an insane difference between "Total Size of Files" and "Size on Disk".  Given that it's close to an order of magnitude, I need to address that at some point.

I'm looking to increase the number of sensors on the board.  I'm playing around with a GY-80 board that I got off of eBay some time ago.  It includes the BMP085 sensor, plus an IMU/Gyro component with a compass.  It was about $20.  I'm wondering if the resolution is tight enough to work as a seismograph, though I'll have to increase the polling rate to something much higher than once a minute.  Luckily, with the processing power of the Raspberry Pi, I could poll the sensor very quickly, analyze the data locally, and only report data that was relevant.  This idea is going to be an add on after some of the other to-do list is achieved.

A big thank you to the write of the Giuseppe Urso Blog.  He's found the datasheets for all of the components on this board (I think).  The ebay seller has not been able to provide good information for me.

Things to do:
I want to improve the webpage.  Right now it's a simple Apache text page that shows the temperature and pressure, along with the system time of the latest measurement (actual time, not epoch time).

I want more sensors.  I'd like a light and motion sensor (again, we're trying to get close to that Hollywood sensor system).  It would be great to incorporate a smoke/carbon monoxide/gas sensor into this build.  A networked, web-enabled hazard detector would be incredible.  I've already got a couple of sensors for this. To get them to work, I need to grab something that will let me add analog to digital feeds to the board (perhaps this?).

I really think I'd like to incorporate a second temperature sensor.  I'd like my first sensor node to be located just inside the front door.  Running a cable outside to a sensor (MPL115A2) would be pretty easy, and would give me the ability to log the weather outside compared to the environment inside.  The capability would also be nice if Angel decides to start working with herps again.  This would allow us to monitor the inside and outside of the tank.

The webpage needs serious work.  I'd like to be able to generate graphs of the data, on the fly (click on the parameter, and it brings up a graph of the last hour.  Click on that graph it shows the last 12 hours.  Click on that, it shows the last day.  Week, month, year, etc).  My skills with Python are not up to the task yet.  Hell, my skills with HTML are essentially non-existent (My webpages in the past have all used Dreamweaver).  I need to see if I can merge the two, and someone get the Python code to play nicely with a Dreamweaver generated page.

Automated alerts.  We'll go back to the Hollywood example for this one:  When the bad guys are breaking in, I need the network to tell my cellphone (or bring up an alert on my computer).  A more practical concept:  When the house gets too hot, I need to be told.  When the house is on fire, I need to be screamed at.

I want to keep the cost down.  The average cost, per node, should be less than $100.  At this price point, folks can afford to pick up a couple of nodes to watch their doors.  As they like it more, they could grab additional nodes for other rooms in the house (I want to be able to control my small home theater system using my cellphone and an IR equipped node).

Webcam support.  The Pi has two USB ports.  Once the node is developed, there is no reason to have the USB ports in use.  A web cam is a cheap (I saw a couple for under $10 the other day) way to gain tremendous amounts of information about a locale.  Even if the camera is only used to snap stills to send to a remote site (or just log locally) the idea has tremendous value.  As it stands, I haven't even tried hooking up a camera to the USB ports.

Free and open code.  An idea like this is only as usable as the guy making everything.  I'm not an engineer or computer scientist.  If I could get a couple of those guys interested in the project, they'd be able to do incredible things with it.  More to the point, they'd see ideas that I'd never even consider.  This project, as an open source project, has real potential.  I'm going to work on setting up a GitHub account, and making my code public (I'll warn you, it's ugly code).

I'll post up more as I get it.

Late edit:  I'm starting to look at Lady Ada's Raspberry Pi WebIDE.  I spent the afternoon/evening learning BitBucket, and now I've got a BitBucket account with the code on it (PiLog).  I may not be doing things correctly, so the repository may be a little bizarre over the next couple of days.  The code that was loaded tonight was tested to work, though your mileage may vary.

WiFi Sniper Rifle

I'm working an insane amount. Between the hospital and school, it doesn't leave much time. I stuff that time with the consulting work, and efforts on a new project to make a fair amount of money.

This post is about none of that.

One of my classes last semester was Wireless Network Security. It seemed to me that like many security problems, this was one of access. To top it off, because many people (and still some organizations) use shoddy security, if you can just get access, you are on the network. I've sat in a couple of dining rooms and offices showing clients how quickly their network can be compromised by not using their security tools correctly.

I'm also getting ready to go on vacation in the wilds of Canada. I'll be honest, I like my internet to be readily available, wherever I go. The last time I was there, we had some issues with signal and antenna aiming. I've been thinking about that problem ever since.

I had some parts lying around the house. Specifically for this project I used only a couple of real parts:
1x 802.11 2.4GHz "25dBi" antenna (Supposedly it works on 5GHz as well, I haven't tried)
1x 802.11n MIMO USB adapter, with two removable antennas
1x AR-15 Lower Receiver with handle (Airsoft Surplus, no modifications needed)
1x Removable stock
1x Cheap Bushnell Scope w/mounts
1x Short length of P-rail to mount the scope

I also used some PVC piping (1 inch, I think) to act as a pillar for the antenna, lower receiver and scope to attach to. I made a small acrylic block and secured it to the PVC pipe as a connection point between the PVC and the lower receiver. Various screws, nuts and some scrap wood were used (The scrap wood was planed to fit in the butt of the PVC, to further secure the PVC to the lower receiver. Another plug was fit to secure the pistol grip to the lower receiver).

I sent a picture to a friend of mine. I think I need to do this with all of my kit-bashes from now on. In the past he's typically been working next to me, when I do these things. He frequently says things like "Are you sure you want to....", or "Hey man, that's not real smart....", or "Is something burning?"
In short, he's the safety cut-out for many of my projects (Despite the fact that he literally has an entire self-inflicted injury category named after him).

His first reaction "Dude! (He's 37 or something) Dude! Is that a railgun?"

So I disappointed my best friend, but again, he probably saved me some grief by showing me a big problem.

This thing looks just like a firearm. More to the point, it's a scary firearm that will make everyone twitch if they see it. Not exactly the kind of thing you want to hang out with on a hill, and point at random dwellings to get an idea of its range.

Now, as an aiming device, this thing is going to be great. I'll be able to visualize my target antenna, and then slowly move the system around to get the best signal. However, I already recognize the difficulty of typing while shouldering the "rifle".

To combat that (and the scary pointing issue), I'm working on a tripod mount for the antenna and PVC assembly. Once the signal is established, I can disassemble the stock and lower receiver around the antenna/PVC assembly, which are secured using a stable tripod.

This is going to work really well in the Wilds of Canada (It sounds cooler when I capitalize it), and at home, I probably won't need the extreme range features of the whole build. I may look at a method of just securing a hand grip directly to the PVC. Then it's going to look like I'm aiming a giant linear antenna, instead of a railgun.