Since my previous post I have added a couple additional temperature sensors to my piHouse project. One is an outdoor temperature sensor that I previously programmed but never installed outside, and the other is a new sensor in my bedroom. This involved some hardware planning and effort installing because I had to run a cable through the house and outside, but once I tested the new cable run, it was relatively simple to duplicate the software for the sensors I already had.
The part of this that took the most time was pulling the cable and then soldering the connections. The biggest problem I have is placement of the outdoor sensor. I am having issues with direct Sunlight.
Here are some highlights, you can find the whole story here. This time I also include some examples of the commands I use on the raspberry pi to obtain the data.
When testing my hardware connections, I use this command to ask the pi to take a reading and then display the result to the command line:
house@raspberrypi ~ $ cat /sys/bus/w1/devices/28-00000512f401/w1_slave 2>&1
The Laboratory B crew had a great time at this year's two day Champlain Mini Maker Faire! This year we had additional support from FairPoint Communications to allow us to teach kids & adults how to solder. We had really impressive students this year, many of whom have seen us before at the previous events. Many people were coming back for their second or even third time. Good work everybody and thanks for coming out to see us! As usual, if you had trouble with your kit or ran out of time please feel free to swing by the Lab, but let us know your coming (Info@labotatoryb.org) Awesome!
Laboratory B is all set up and ready to see you at Champlain Mini Maker Faire this weekend! The event is on Sat. October 4th 10am - 5pm, and Sun. October 5th 11am-4pm at Shelburne Farms in Shelburne Vermont.
Lab B has been at the Maker Faire since it started 3 years ago, and like last year and the year before, we'll be teaching kids & adults how to solder! FairPoint Communications made a donation to help provide kits, and we have four kits from SparkFun in the mix this year; Weevil Eye, Big Time Watch, Simon Says & Mr. Roboto.
From our excerpt in the schedule:
"Join the folks at Laboratory B for a self-paced soldering workshop. We bring the soldering irons and the kits, you bring the desire to learn. We will have kits from SparkFun and all the required supplies and safety gear for you to sit down and learn how to solder, and when you finish you take the kit home! Have you soldered in the past but are not familiar with some of the newer techniques such as surface-mount soldering? No problem! There will be beginner kits, intermediate kits, and advanced level kits to fit all skill levels."
In March I posted about using my Raspberry Pi to monitor my furnace and the temperature of my apartment. I moved over the summer and the new apartment does not have the same type of heating that the last apartment did. So I had to make some changes.
The Pi now interfaces with a Rinnai heater, which was slightly more complicated than the furnace thermostat.
Here are some highlights, you can find the whole story here.
I get asked about being a hacker, what's a hacker, isn't hacking bad etc etc, all the time. Thanks Nova Labs for putting together this video which says everything I would have!
Keep up with some of the Laboratory B open source code by joining us on GitHub!
Last weekend Doug whipped together a toy steganography device called "Stegosaurus" [github] -- it will take a PNG image, and using a (very very basic) steganography [wikipedia] algorithm stores a payload in the least significant bits of the color definition of pixels in an image. It's a node.js module, and you can even install it with NPM.
It could use a little improvement if anyone is interested in forking it! It needs some testing with binary files. It needs a way to store the length of the message. And ideally, it'd use a pre-shared key (maybe?) to allow you both: A. define where the payload is hidden in the image, and B. actually encrypt the payload (which is, as of now, unencrypted). Which makes it so it doesn't follow Kerckhoff's Principle [wikipedia].
...Unfortunately every single message is decoded as "Drink more ovaltine" [youtube] (...just kidding. it'll do whatever payload you want)
When Laboratory B got started we were excited about the possibility of other hacker/maker/community workshop spaces starting up and sustaining in Vermont. That's why we created Vermont Hackerspaces Inc as non non-profit designed to help others do great things. The Foundry is a community workshop getting started in the Northeast Kingdom. Building on the grit, and hard work they are going to bring together a community of creators, tinkers, crafter, artist and entrepreneurs. This great community is going to build a great new space for creation and innovation!
On July 7th, Vermont Hackerspaces Inc, agreed to become the Foundry's fiscal sponsor while they get started. The Foundry is looking to develop it's own 501(c)3 but it's a long when from getting going to handling your own books. Check out the website or Foundry's facebook page and Foundry Info Pack for more info.
I made an upgrade to my Lego key ring. Now With USB! Basically, I put a 16G flash drive into some Legos and put them on the key ring.
Here are a couple shots, you can find the whole story here.
tldr? "Life giving bazooka" is an example of an Ethereum contract that represents a pyramid scheme. Check out the scheme @ github. It's called "life giving bazooka" as a knock on multi-level-marketing schemes.
We've been having a lot of fun having some nights where we're chatting up Crytpocurrency, and recently we got together and had a working session taking a look at Ethereum. We got the client up and running, and moments later gdot had a little "banking contract" running, from an LLL (lisp-like-language) tutorial.
Which is awesome... But, I really wanted to write in the "c-like-language" (CLL) -- that's what I tend to get. So, I found Vitalik's got a CLL compiler, but it's pretty alpha. Also, it's made progress to work with PoC4, which isn't released yet. All the main releases of the clients (which you can download), are PoC3 based. So, I went ahead and fixed a few things in his compiler, and I'm maintaining my own branch @ https://github.com/dougbtv/compiler/tree/poc3-compat.
But, to make it easier, I've been maintaining my own pre-processor (inspired by the C pre-processor) that makes a few things a little easier to work with. You can download my cll-preprocessor at github, and it includes submodules that fix the things that I needed to get Vitalik's compiler working properly, especially with PoC3.
So... Where's this pyramid scheme!?! It's also on github! There's quite a bit more information there for you to read about how it works, and instructions to run it if you so please.
I've been working on a Raspberry Pi project and got it running this weekend. This post is about the hardware and the installation. I will post later about how the code works.
I have been using microcontrollers for a long time now. I started in college as part of the program and have never stopped. Professionally, educationally, hobby, I've done projects of all types.
Recently I decided to try something with a Raspberry Pi. It is the next step up, basically being a little computer. This was so I could play with Linux again (it's been years) and do something with a web browser. These are things I don't have experience with and have been interested in learning for some time.
The project I settled on was a monitor for the furnace in my apartment. This monitor will measure temperature(s) and sense if the furnace is running, then log this data. There will be a web interface that will draw graphs of the data on a daily basis. There will also be an LCD screen on the pi so that I can see the current data without needing a web browser.
Part 1: Hardware
The first step was to make sure I could sense whether the furnace was running. My furnace is controlled by a thermostat. A thermostat is a temperature controlled mechanical switch. Mine looks like this (The wire hanging down was added later):
I needed to open this up to see how it worked. So, I pulled off the ring on the front and exposed 3 screws holding it to the wall. I took out the screws and pulled the switch off the wall. I was left with a mounting plate that included a set of screw terminals with a 2 conductor wire attached. This is the wire running to the furnace in the basement that controls the furnace.
The screw terminals were labeled as RH and W. I took out my mult-meter and started doing some measuring.
Open (Furnace off): RH -> W, 25.8 VAC
Closed (Furnace on): RH -> W, 0 VAC @ 95mA
This means that I need to monitor the voltage across terminals RH and W. If voltage is present, the furnace should be off. The 95mA is mostly unimportant because the thermostat is going to stay in place. I just need to make sure the pi doesn’t draw so much current that it turns on the furnace on it’s own. I drew up the below circuit to accomplish this using a rectifier circuit and an opto-isolator fed into GPIO24.
In this circuit, when the thermostat is open, the 10K resistor attached to the terminals limits the current feeding the 4 diodes, which function as a bridge-rectifier. This rectified AC then drives the LED of the opto-isolator. When the LED is lit, is turns on the transistor, shorting GPIO24 to GND with a 1uF cap for smoothing because its an AC signal. When the thermostat is closed, there is no current driving the opto-isolator and GPIO24 is pulled up to to 3.3V by a 100K resistor.
With the furnace monitoring designed, I had to decide on a temperature sensor. Unfortunately, the raspberry pi doesn’t have any built-in analog inputs. This was a little disappointing because it’s a standard feature on most microcontrollers I have used, however this is a computer. After a little research, I settled on a sensor that uses the Dallas 1-wire protocol. This is a serial bus that is similar to I2C. I liked it becuase there is pi support and since it is a bus, it is expandable (multiple sensors) without using more inputs. I found some DS18B20 1-wire Temperature Sensor ICs in a probe package with wire attached on Amazon, a bought a few.
Following the datasheet recommendations, I wired up the temp sensor like this:
The last piece for this was an LCD screen. I did some research and picked a product from Adafruit that has a 16X2 RGB LCD Screen and 5 buttons on a “shield” style board that plugs into the GPIO header on the pi. I ordered one and when it came in, I soldered it together.
After much programming (That will be a future post), I had all the parts working. So it was time to put the unit together. I plugged the LCD screen into the pi, then soldered some wires to the backside of the header-pins on the LCD shield. The other ends of the wires go to some proto-board where I built the schematics pictured above. I then added a 2-conductor wire in parallel to the thermostat and connected the other end to the pi’s “furnace” input. I wired up the Temperature sensor. I mounted it all to a bookshelf and fired it up.