Oh this is exciting! I’ve been trying to figure out how to get motion events from my IP camera into my home-assistant instance running on my Raspberry Pi, and I just did a successful test! It works! Hooray. Briefly, I set up an email server on the Pi, have the camera email the Pi, have the email server trigger a script which parses the email for key words and sends MQTT signals as appropriate, at which point the home-assistant MQTT client sees them and triggers automations (like blinking a light to scare people off). Here’s how I did it.
As documented earlier, I made one of those CRT-in-a-winebottle things. I used a cheap 2-stage mechanical vacuum pump for it. Well, it was so good that my boss wanted to use it as a science demo at some dinners he gives, so it’s been permanently transferred to work. So I need a new pump, and a new chamber!
I got my first motorcycle, a 1997 Suzuki GS500, in 2007. It was great for a long time. I cut my motorcycle maintenance teeth on it, starting with gas line issues, shim adjustments, and an oil leak fix. Things escalated to taking the pistons out and head off to get the top-end rebuilt. Issues kept popping up more frequently than I liked so I sold it in 2012 and got a brand new Suzuki DL650A V-Strom ABS (aka “Glee”), feeling like I had had enough maintenance for a while. I only felt a little shame when I took it in to the shop for some routine maintenance
Well…I guess I’m back in the routine. After I totaled it but kept it, I got warmed up doing basic maintenance stuff on it. So when an issue came up recently, I decided to fix it myself.
UPDATE Jan 2017: Whaddaya know? The stator was just recalled due to a tendancy for this to happen.
I just configured a pretty slick burglar alarm with the open-source Home-Assistant platform running on my Raspberry Pi. It can be armed to trigger when a door is opened and/or when a motion sensor goes off.
Then, a sequence of events happens:
An IR LED turns on my stereo
A sound file I cobbled together starts playing. It starts with a computerized voice saying that yourentry been detected and recorded, then it beeps for a while (giving you time to disarm), and then it goes into a blaring siren noise. Quite the escalation!
A light blinks on and off a few times
A camera takes a series of snapshots of the area
An email is sent to my phone with the snapshots, showing me what’s going on
You may have seen my earlier post about my new home automation setup. Well I just upgraded it! I just finished testing out a new infrared remote control send and receive capability and it is pure awesome. Here’s what I can do now from within home-assistant:
Turn on and off my new DeLonghi portable air conditioner from Costco, and set the temperature to whatever
Turn on and off the TV and press any buttons from its remote control
Turn on and off the stereo and virtually press any buttons from its remote control (which I never even had!)
Use an old random blueray remote control to set scenes, turn lights on and off, etc. (basically do anything under home-assistant’s control)
This post is about how I did it on my Raspberry Pi.
I went over to my friend’s house last night to help get home-assistant on a Raspberry Pi working for his z-wave door sensors and siren. The Ecotech sensor showed up fine but the Aeotech recessed one (Recessed Door Sensor Gen5 , ZW089-A) did not show up by default. After poking around in the logs for a while, we realized that it was sending BASIC_SET command classes instead of BinarySensor commands. Apparently (I thought I had fixed this already), home-assistant doesn’t recognize the BASIC_SET commands just yet. But looking at the config file for this device, we discovered that config item 121 changes which kind of report this sensor sends: Continue reading Using an Aeotech recessed door sensor in home-assistant
Ever since I installed a mobile ham radio in my Subaru, there has been a pretty noticeable whine that revs up and down with the engine. I got a few complaints that the whine was on my transmitted signal. I can also hear the whine through my subwoofer, though it is quieter. I needed a low-pass filter to let the DC from my battery make it through to the radio while blocking any alternator-induced AC coming along for the ride. I was going to just buy one but then I searched the web a little and found that it was fun and easy to build my own!
In this post, we’ll take a brief measurement of regular old FM radio stations and try to determine where we are. It’s like a GPS but with local FM transmitters instead of satellites. I did this just for fun. I wonder if it could be used for indoor location and stuff? It is nowhere near as accurate as GPS. But whatever.
Reading FM radio signal power
The first step is to get a reading of all the nearby radio stations. I used gnuradio and a HackRF One software defined radio. A simple flow-chart that takes the FFT and dumps it to a file is all I needed. I had to throttle the I/O or else my computer would freeze. I used 16M sample rate to have as wide a bandwidth as possible.
The gnuradio flow-chart used to gather data
The file sink saves the FFT results in 4-byte integers and just has one 1024-length vector after the other. In a few seconds, I had a 50 MB of data. I did all the post-processing in an external Python script.
I’ve always dreamed of having a “smart-home.” There’s just something cool about being able to flip switches and read sensors and have a program turn a light on when you open the door, but only if it’s dark. This post is about home automation.
Turning 32 may not seem like a very excitingbirthday, but it is! In fact, it is the most momentous birthday of all, because it’s the first time in your life that you can’t show your age on a single hand.
Counting in binary.
First, a refresher. Binary, (popularly known as the number system of computers which think in terms of ons and offs, as represented by ones and zeros) is base-2, whereas good old decimal is base-10.
My wife got me an early birthday present: Philips HUE Color-Changing LED lights! They’re incredible. Look:
Right now I’m controlling them with my tablet, which is fine for changing colors and setting light alarms. I can even control them from afar thanks to my VPN. I will soon hook them up to my nascent Raspberry Pi powered home automation system (using the open-source Home Assistant program) that will allow me to trigger them based on various events like motion, doors opening, weather changing, or whatever. The future is here!
Each bulb uses 9 Watts but makes the same amount of light as a 60W conventional bulb, so they’re very eco-friendly. Furthermore, since they’re LEDs, they should last for 15 years of normal use! They communicate with a little hub that uses the ZigBee protocol (like Bluetooth but lower power and lower speed, good for home automation stuff).
Downside: They’re pretty pricey. I expect their coolness to drive demand enough to bring supply up. Expect these bulbs for $10 in the next few years.
Sending and receiving text with Morse code light pulses across the room (or to your neighbor) is a fun and cheap project you can do on a Raspberry Pi or Arduino or any other microcontroller. This post explains how I did it, and how you can do it too.
It’s working!
Hardware
The hardware is simple and cheap. Here’s my parts list:
Raspberry Pi B+ as the controller. This does the sending, receiving, and signal processing.
Photoresistor – Just a little guy that has variable resistance based on how much light is hitting it
A 220 Ohm resistor – to make a voltage divider with the photoresistor for reading the input signal
MCP3008 10-bit Analog-to-Digital Converter (ADC) – Since the RPi doesn’t come with an ADC, this is required for converting analog voltage from the photoresistor into a signal I can process on the RPi.
Laser module – to transmit with laser light. I got one from sunfounder.com for like 3 bucks.
Breadboard, wires
You can learn how to use the ADC at this Adafruit tutorial. I decided to talk to the ADC with the RPi’s hardware SPI interface, which I had already enabled. I wanted to be able to go very fast. (You can alternatively do SPI off of GPIO ports with software, if you prefer.) The laser just hooks directly between a GPIO and +5V. Here’s the layout:
Sensors are fun!I wanted to keep an eye on the temperature of one of my home physics projects and realized I needed a thermocouple and a convenient way to read it. This post is about how I got one and wrote a Python program to send the data from a Raspberry PI over the network to my laptop, which plots the results in real time.
Thermocouple in fridge
I bought a K-type thermocouple for several dollars that ranges from -100°C to 500°C. The Seebeck effect that makes it work only gives microvolts per degree so I needed a good amplifier for it. And since I wanted to read it on a Raspberry PI (which only has digital inputs), I’d need an analog-to-digital converter (ADC). Conveniently, the MAX31855 does amplification and ADC and is like $15, so I got one. Sweet. There’s even a Python library for it that makes it easy to access. Double-sweet.
Alright, this is an oldie, but ah… well… it’s and oldie where I come from. In 2005, I had some healthy spare time and decided to build a flux capacitor. I posted the details on my old webpage. I just rewired a battery pack on it and it’s working fine so I figured it was time to get it back online again. So, here it is. How to build a LED flux capacitor.
The Concept
In the movie Back to the Future, Dr. “Doc” Emmett Brown completed his life goal of making the flux capacitor a reality. Here’s the story:
“I was standing on the edge of the toilet hanging a clock, the porcelain was wet, I slipped, hit my head on the edge of the sink — and when I came to I had a revelation! A vision! A picture in my head! A picture of this! This is what makes time travel possible! The Flux Capacitor.”
-Doc, Back to the Future
The Flux Capacitor
Unfortunately, I didn’t have room for the time circuits or nuclear reactor to generate the 1.21 jigawatts that the flux capacitor needs to travel in time so we’re going to have to go with the next best thing: A 30 LED sequencer!
I recently got a HackRF One software defined radio (SDR) to go along with my new Ham radio hobby. I’m new to all this, but one of the first things I noticed was that I was picking up a lot of radio frequency interference (RFI). I had purchased a RFI shield as part of the kit but had to install it myself. This post shows how I did it.
Opening the HackRF enclosure
The first challenge is opening the enclosure. To do this, first take the bolts and washers off of each of the SMA antenna connectors. Now, go in above one of the connectors with a little screwdriver (maybe put electrical tape over it) and start popping up the enclosure. Eventually you will pop it all up.
Installing the RF shield
Now we have to solder the RF shield onto the board. There’s a dotted line that shows where it goes.
Linux is an open-source operating system that you can download and install on your computer to complement (or even replace) your current operating system (Windows or MacOS). It started out when some guy wrote some code and gave it to the world community for free. It has become huge, and now provides the engine of Android phones and tablets, runs about 40% of the servers that make up the internet, and powers 97% of the world’s supercomputers. It’s a stunning success in the social open-source experiment.
For home use, it is just now ditching a reputation of being only for nerds, scientists, and hobbyists like me, with lots of headaches getting software and hardware working nicely with it. Really, I’ve been using it at home on my laptop since 2007 and it’s evolved to a point where I think it’s totally usable for most people. It also has a focus on privacy, security, and stability. Since the code is open (everyone can see and change how and why it works), there’s less mystery about what anyone is doing with your computer and more control to get it to do what you want. It was the speed and low-resource requirements that brought me to Linux originally, and it’s the quality and open philosophy that has made me a real proponent.
I was doing some speed tests with cython in Windows and started wondering what the import precedence was between py, pyc, and pyd files (not to mention pyo). So I did a simple little test with two files, test.py and test2.py. Test.py just had a print statement in it and test2 just imported test1 (so it would create the pyc). I compiled test.py with cython into test.pyd and then changed test.py to print something else.
Conclusion: The pyd file was always imported if it was present. If it wasn’t there, then the new print statement from the new test.py was printed out. I’m sure this is documented somewhere but I’m not sure where. The conclusion holds if there are “optimized” pyo files present as well.
So with all the recent revelations about everyone spying on everyone, I decided to look into what it would take to get fairly secure communications capabilities so my stuff wasn’t just in the open. I became a cryptography dilettante, and it is pretty fun. I have explained what I’ve learned to a few people so I figured I’d just write it all down here. It’s surprisingly easy and free to do.
Writing secure emails or transferring files securely
One basic thing you should be able to do securely is to send an email or file to someone that only they can open. To do this, you can use a free technology called Pretty Good Privacy, or PGP. Some nice free software that uses this is called the Gnu Privacy Guard. Go to GnuPG.org and download the relevant files. If you’re on Windows, get gpg4win (be sure to install GPA when it asks), Mac users can use GPGTools, and Linux users can just get GPG and GPA (Gnu Privacy Assistant) from the repos. Step 1 now is to generate your public/private key pair. These are basically just really large numbers that are intimately tied together in a way that if someone encrypts an email or file against your public key (which you will give to them), then only he/she who possesses the private key can decrypt it. So you publish your public key far and wide (here’s mine) and keep your private key very secret and safe (and backed up on a USB stored in your safe). Anyway, just go into the GPA program and click Keys->New Key. This will generate your keypair. Protect your private key with a strong password (10+ characters, no dictionary words. And don’t do capital letter + lower case letters + numbers + symbols in that order. Everyone does that!)
Now that you have a keypair, just right click it and say export key. This will export your public key to a file. Email the file or publish it online or whatever to anyone and everyone. When they send you an email or file, they will encrypt to this public key. Meanwhile, have your friends do the same and then import their keys that they send to you (keys->import key).
To actually encrypt, just go to Windows->clipboard and type some juicy secret. Then click encrypt and choose who you want to encrypt it to. Finally, just email them the ciphertext. It’s best to use a text-mode email by the way, so do that (it’s an option in gmail, etc.). They will get it and they can copy and paste it into their GPA and click decrypt, enter their secret password (which unlocks their private key), and they’re off. Phenomenal. Files can go the same way, just choose window->file manager instead of clipboard.
a secret message
Alright! Super easy. If you use Thunderbird to read your email, you can use the Enigmail plugin that seamlessly encrypts for you. Nice! If you want a web-based email account that has tightly integrated PGP and no ads, try out hushmail.
There are a bunch of other cool things you can do with PGP like electronically sign your messages. This is something that you put at the end of an unencrypted (or encrypted) message that someone can “verify” against your public key. If no one has tampered with the message and you wrote it, then this verification proves that it was you who wrote the message. So cool.
Chatting and browsing the web anonymously and securely
So, great. Now, what if you’d like to chat with someone online and not have it be read? That’s your right. One pretty easy way to do it is through something called cryptocat. This is a Firefox extension that allows you to very easily have fairly secure chats. You COULD just click the link and install it, but you should really use The Onion Router too, which anonymizes your web traffic as well. That way, whatever you do online cannot be traced back to you because it hops through a secure set of encrypted layers on different volunteer servers first. So, FIRST go to https://www.torproject.org/ and install Tor and the Tor browser (there’s an android version too!). Then, open up the Tor Browser (which will automatically connect you to the Tor network), and then go to cryptocat and install the extension. Now you can open up a chat room and have a nice time chatting securely and anonymously. Excellent! You can use the Tor browser for anything else too.
Besides using Tor, you might want to stop using Google for many things. I started using DuckDuckGo, which doesn’t save your search history for hackers or rouge employees (or anyone else) to steal later. It’s not as good as google really, but it’s the principle that counts.
Security on your phone
If you have an Android phone, you can get these three cool apps that help with security. First is TextSecure, which allows you to exchange encrypted texts with anyone else who has TextSecure. It also stores your texts on your phone in an encrypted database, so if you lose your phone, no one’s reading your stuff. The same company makes RedPhone, which allows you to speak with anyone securely who has RedPhone. That’s totally sweet. I will admit that the voice quality in the case I used it in so far was mediocre. Finally, there’s Orbot, which is Tor for your phone, anonymizing your web traffic. Fun times.
Securely store files
If you want to keep a USB stick or a part of your hard drive that is encrypted (in case it gets stolen or something), the TrueCrypt tool is fantastic. It can even make a Hidden volume, where if you type a dummy password, dummy files show up but if you type the real password, the real files show up. And no one can prove the real files exist. That gives you what’s known as plausible deniability, a term coined by the CIA.
Encrypting with Truecrypt is different than with PGP because to send the file, the recipient would need to know the password. But how can you send the password securely? With PGP. So might as well just use PGP for the whole transfer.
If you’re a friend of mine who wants to try any of these technologies out with someone, just drop me a line and I’ll play along. I got a lot of this info from a reddit AMA, which you can read here.
Privacy is important, even if you have nothing to hide. Ok have a nice day!
Update: There’s a great collection of related information at this page.
