Hackaday Links: June 7, 2015

I’ve said over and over again that Apple’s MagSafe port is the greatest advancement in laptop tech in the last 15 years. Those charger connectors break, though, so how do you fix it? With Lego, of course (Google translatrix). Use a light-colored 1×4 brick so the LED will shine through.

Want to learn Git commands? Here’s a great game that does just that. It’s a really well-designed game/tutorial that walks you through basic Git commands.

Lets say you’re just slightly paranoid about the Bad Guys™ getting into your computer with 0-days and roller blades. You’d like to connect this computer to the Internet, but you don’t want to leave it connected all the time. The solution? A timer for an Ethernet switch. It’s actually a better solution than doing the same thing with scripts: there’s a real, physical interface, and if the Bad Guys™ get in when you are connected, they could just enable the network adapter anyway. An extremely niche use case, but that’s 99% of the security hacks we see.

The DaVinci 3D printer is an okay printer if you’re cool with the Gilette model. The filament cartridges are chipped, and the software is proprietary. These problems have been solved, and now you can use a standard RepRap heated bed and glass with the DaVinci. At this point, people are buying the DaVinci just to tear it apart.

An Arduino Device that Monitors Your External IP Address

[Bayres’] dad setup a webcam as a surveillance camera for a remote property. The only problem was that the only stable Internet connection they could get at this property was DSL. This meant that the external IP address of the webcam would change somewhat often; the needed a way to keep track of the external IP address whenever it changed. That’s when [Bayres] built a solution using Arduino and an Ethernet shield.

The main function of this device is to monitor the public IP address and report any changes. This is accomplished by first making a request to checkip.dyndns.org. This website simply reports your current public IP address. [Bayres] uses an Arduino library called Textfinder in order to search through the returned string and identify the IP address.

From there, the program compares this current value to the previous one. If there is any change, the program uses the Sendmail() function to reach out to an SMTP server and send an e-mail alert to [Beyres’] dad. The system also includes a small LCD. The Arduino outputs the current IP address to this display, making it easy to check up on the connection. The LCD is driven by 74HC595 shift register in order to conserve pins on the Arduino.

The system is also designed with a pretty slick setup interface. When it is booted, the user can enter a configuration menu via a Serial terminal. This setup menu allows the user to configure options such as SMTP server, email address, etc. These variables are then edited and can be committed to EEPROM as a more permanent storage solution. Whenever the system is booted, these values are read back out of the EEPROM and returned to their appropriate variables. This means you can reconfigure the device on the fly without having to edit the source code and re-upload.

Display Your City’s Emotional State with Illuminated Snow

[Hunter] wanted to do something a bit more interesting for his holiday lights display last year. Rather than just animated lights, he wanted something that was driven by data. In this case, his display was based on the mood of people in his city. We’ve seen a very similar project in the past, but this one has a few notable differences.

The display runs off of an Arduino. [Hunter] is using an Ethernet shield to connect the Arduino to the Internet. It then monitors all of the latest tweets from users within a 15 mile radius of his area. The tweets are then forwarded to the Alchemy Sentiment API for analysis. The API uses various algorithms and detection methods to identify the overall sentiment within a body of text. [Hunter] is using it to determine the general mood indicated by the text of a given tweet.

Next [Hunter] needed a way to somehow display this information. He opted to use an LED strip. Since the range of sentiments is rather small, [Hunter] didn’t want to display the overall average sentiment. This value doesn’t change much over short periods of time, so it’s not very interesting to see. Instead, he plots the change made since the last sample. This results in a more obvious change to the LED display.

Another interesting thing to note about this project is that [Hunter] is using the snow in his yard to diffuse the light from the LEDs. He’s actually buried the strip under a layer of snow. This has the result of hiding the electronics, but blurring the light enough so you can’t see the individual LEDs. The effect is rather nice, and it’s something different to add to your holiday lights display. Be sure to check out the video below for a demonstration. Continue reading “Display Your City’s Emotional State with Illuminated Snow”

The Giant Flip-Dot Display at CES

Flip-dot displays are grand, especially this one which boasts 74,088 pixels! I once heard the hardware compared to e-ink. That’s actually a pretty good description since both use a pixel that is white on one side and black on the other, depend on a coil to change state, and only use electricity when flipping those bits.

What’s remarkable about this is the size of the installation. It occupied a huge curving wall on the ooVoo booth at 2015 CES. We wanted to hear more about the hardware so we reached out to them they didn’t disappoint. The ooVoo crew made time for a conference call which included [Pat Murray] who coordinated the build effort. That’s right, they built this thing — we had assumed it was a rental. [Matt Farrell] recounts that during conception, the team had asked themselves how an HD video chat for mobile company can show off display technology when juxtaposed with cutting edge 4k and 8k displays? We think the flip-dot was a perfect tack — I know I spent more time looking at this than at televisions.

Join us after the break for the skinny on how it was built, including pictures of the back side of the installation and video clips that you have to hear to believe.

Continue reading “The Giant Flip-Dot Display at CES”

Home Automation Setup Keeps You Informed

[johannes] wrote in to tell us about his latest project, a home automation setup he named Botman. While he calls it a home automation system, controlling lights and home appliances (which it does wirelessly on 433MHz) is just a small part of its functionality. The front panel of Botman includes a servo which points to laser-etched icons of the current weather. It also has a display which shows indoor and outdoor weather conditions along with the status of public transportation around [johannes]’s house.

Botman is built around an Arduino with an Ethernet shield. The Arduino has very little memory, so [johannes] used the Google Apps engine as a buffer between his Arduino and the JSON APIs of his data sources. This significantly reduces the amount of data the Arduino has to keep in memory and parse.

[johannes] also wrote an Android app that communicates with Botman. The app has buttons for controlling lights in his house and duplicates all the information shown on the front panel. [johannes] also built some logging features into Botman. The temperature readings and other information are uploaded from the Arduino to a Google Docs spreadsheet where he can view and graph them from anywhere. Check out the video after the break to see Botman in action.

Continue reading “Home Automation Setup Keeps You Informed”

Bridging Networks With The Flip Of A Switch

The TP-Link TL-WR703n is the WRT54G for the modern era – extremely hackable, cheap, and available just about everywhere. Loaded up with OpenWRT, it’s capable of bridging networks: turning Ethernet into WiFi and vice versa. This requires reconfiguring the router, and after doing this enough times, [Martin] was looking for a better solution. The SOC inside the WR703n has two exposed GPIO pins, allowing [Martin] to choose between WiFi access point or client and between bridged or NAT/DHCP.

According to the OpenWRT wiki, there are a few GPIOs available, and after connecting these pins to a DIP switch, [Martin] could access these switches through the firmware. The hard part of this build is building the script to change the settings when the system boots. This script looks at the state of the GPIOs and changes the WiFi into client or access point mode and tries not to muck about with the DHCP somewhere off in the cloud. Yes, we just used cloud in its proper context.

The only other hardware to complete this build was a simple USB to serial converter that should be shoved into the corner of everyone’s workbench. Not bad for an extremely minimal soldering and configuration required for a something that’s extremely useful.

Protocol Snooping Digital Audio

More and more clubs are going digital. When you go out to hear a band, they’re plugging into an ADC (analog-to-digital converter) box on stage, and the digitized audio data is transmitted to the mixing console over Ethernet. This saves the venue having to run many audio cables over long distances, but it’s a lot harder to hack on. So [Michael] trained popular network analysis tools on his ProCo Momentum gear to see just what the data looks like.

[Michael]’s writeup of the process is a little sparse, but he name-drops all the components you’d need to get the job done. First, he simply looks at the raw data using Wireshark. Once he figured out how the eight channels were split up, he used the command-line version (tshark) and a standard Unix command-line tool (cut) to pull the data apart. Now he’s got a text representation for eight channels of audio data.

Using xxd to convert the data from text to binary, he then played it using sox to see what it sounded like. No dice, yet. After a bit more trial and error, he realized that the data was unsigned, big-endian integers.  He tried again, and everything sounded good. Success!

While this is not a complete reverse-engineering tutorial like this one, we think that it hits the high points: using a bunch of the right tools and some good hunches to figure out an obscure protocol.