Electric Window Mechanism Into A Electric Screen Door

September 29, 2020 by 10 Comments

In many parts of the world leaving open a door or window is a good way to get a house full of bugs. Remembering to close doors behind them can be surprisingly hard for members of the human race, so the [DuctTape Mechanic] used the components from a car’s electric window to automate his sliding screen door.

After the excess pieces were cut off the rail, the motor and rail were mounted on top of the door frame. A long bolt is attached to the moving plate on the rail, which pushes on the pack of the door to close it. After closing, the mechanism returns to its open position, allowing the door to be opened by hand again. The motor is controlled by an Arduino running a very simple sketch, which senses if the door is closed with a microswitch and starts a 10 second countdown once opened. Two relays are used to create an H-bridge circuit to drive the motor in both directions.

It doesn’t look like there is any provision to detect if it is obstructed. A simple solution could be to make the push rod spring-loaded, so it can slide over the door if there is excessive resistance.

If you only want to let certain creatures into your house, we have no shortage of automated pet door for your hacking pleasure.

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Push Pedal For Privacy

September 29, 2020 by 17 Comments

Many of us in the secret Hackaday lair use gaming hardware at our work desks because it is reliable and performs well. We are not alone, and maybe you are reading this on your coffee break over a 20-button mouse. We wager that [Thiago Ribeiro de Azeredo] has this mindset because he converted some old analog gaming pedals into teleconferencing tools for his home office. Now that he is not racing to the office, he has to take a lot of computer calls, and he must quickly and covertly mute his microphone when his howling son tries to take the stage.

The pedals were gathering dust when he started working from home, but they are unretired for the upgrade. Inside, there is no mystery, just a couple of spring-loaded variable resistors, so he adds an Arduino Nano a couple of 4.7 kΩ resistors to create a voltage divider. The Nano doesn’t have native Human Interface Device (HID) functionality, so a Python script receives the serial port signals and toggles an application bar notification so he can see the microphone status. With two pedals, he can press-to-talk or lock his microphone on and off. We have to wonder, did he write the software during a meeting?

We love the idea of controlling our battle stations with our feet or seeing a bunch of RGB keyboards used as a low-res display.

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A Good, Hard Look At Pre-Stressed Concrete

September 29, 2020 by 43 Comments

From the looks of the average driveway or sidewalk, it may seem as though concrete is just destined to crack. But if concrete is so prone to cracking, how are we able to use it in so many high-stress applications like bridges and skyscrapers? This question came about while I was researching 3D-printed thermite for an article. Thermite is often used in welding railroad tracks, and I linked a video of fresh tracks being welded that had concrete ties. I knew I had to find out how concrete could be made to withstand the pressure of freight trains.

On its own, concrete is brittle and has no give to it at all. But that doesn’t mean it isn’t strong. Although concrete has good compression strength, the tensile strength is quite poor. Around the late 1800s, someone thought to fortify spans of concrete with steel reinforcing bars, better known as rebar. Steel can stretch, adding steel bars gives the concrete some tensile strength to go along with its compressive strength. Rebar also allows for thinner slabs and other members.

Rebar Only Goes So Far

Parking blocks are meant to be replaced occasionally. Image via Checkers Safety

Rebar or mesh-enforced concrete is good for things like parking lot blocks and roads, but it still fails before it ought to. In fact, it usually has to crack before the rebar can chip in any of its tensile strength.

In high-stress concrete applications like bridges and skyscrapers, it’s terrifically important to avoid deflection — that’s when a concrete member flexes and bends under load. Deflection can cause the modern glass skins to pop off of skyscrapers, among other problems.

A solid, rigid bridge is much nicer to walk, drive, and bicycle on than a bridge that sways in the breeze. But how do you do make a rigid bridge? One solution is to apply stresses to the concrete before it ever bears the load of cars and trucks or a steady schedule of freight trains.

Pre-stressed concrete is like rebar-enforced concrete, but with the added power of tension baked in. By adding stress to the concrete before it goes into service, deflection will be reduced or perhaps eliminated altogether. With the addition of tensile strength, more of the concrete’s own strength is able to come into play.

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All The Workshops, And The SMD Challenge Happening At Hackaday Remoticon

September 29, 2020 by 16 Comments

Last week we announced the first fifteen workshops happening at Hackaday Remoticon, November 6-8, 2020. The weekend really is packed full of these hands-on events, and you’re invited to participate from anywhere in the world. Today we’re excited to announce the rest of the workshops, all of which are currently open for registration.

Can we get a few hundred people to show off their soldering skills (or amusing lack of skills) from their own workbench during the event? We think we can, so we’re running the SMD Challenge virtually this year. All of this, plus keynote talks, demos, a show-and-tell, and more make for one wild weekend. Read on!
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Linux-Fu: Making AWK A Bit Easier

September 29, 2020 by 18 Comments

awk is a kind of Swiss Army knife for text files. However, some of its limitations are often a bit annoying. I’ve used a simple set of functions to make awk a bit better, although I will warn you: it does require GNU extensions to awk. That is, you must use gawk and not other versions. Your system probably maps /usr/bin/awk to something and that something might be gawk. But it could also be mawk or some other flavor. If you use a Debian-based distro, update-alternatives is your friend here. But for the purposes of this post, I’m going to assume you are using gawk.

By the end of the post, you’ll see how to use my awk add-on functions to split up a line into fields even when there is no single character to separate all fields. In addition, you’ll be able to refer to the fields using names you decide. You won’t have to remember that $2 is the time field. You’ll say Fields_fields["time"] instead.

The Problem

awk does a lot of common work for you when you use it to process text files. It reads files a record at a time. Normally, a record is a single line. Then it splits the line on fields using whitespace, or some other choice of field separators. You can write code that manipulates the line or individual fields. This default behavior is great, especially since you can change the end of record character and the field separator. A surprising number of files fit this sort of format.

Until, of course, they don’t. If you have data coming from a data logging instrument or some database, it could be formatted in a variety of ways. Some fields might have structured data with a variety of separators. This isn’t a deal-breaker. Since you can get at the whole line, you can do almost anything you want, but the logic is harder and the whole point to using awk is to make things easier.

For example, suppose you had a file from a data recorder that had an eight-digit serial number, followed by a six-character tag, and then two floating point numbers separated by colons. The pattern might look like

^([0-9]{8})([a-zA-Z0-9]{6})([-+.0-9]+),([-+.0-9]+)$

This would be hard to handle with the conventional field splitting and you’d normally just write code to split everything apart.

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WiFi Hacking Mr. Coffee

September 29, 2020 by 42 Comments

You wake up on a Sunday, roll out of bed, and make your way to the centerpiece of your morning, the magical device that helps you start your day: the coffee machine. You open the companion app, because everything has an app in 2020, and select a large latte with extra froth. As you switch open a browser to check Hackaday, the machine beeps. Then the built-in grinder cranks up to 100, the milk frother begins to whir, and the machine starts spraying water. Frantic, you look at the display for an error code and instead see a message instructing you to send $75 to a bitcoin wallet, lest your $300 machine become a doorstop.

Outlandish though it may seem, this has become quite a real possibility, as [Martin Hron] at the Avast Threat Labs demonstrates. In fact, he could probably make your modern macchiato machine do this without setting foot in your house (so long as it comes with a built-in ESP8266, like his did).

Building on others’ work that identified the simple commands that control the machine over it’s WiFi connection (nothing says “brew me a nice cup o’ joe” like 0x37), [Martin] reverse-engineered the Smarter Coffee companion app to extract and reverse engineer its firmware. He was actually able to find the entire firmware image packaged within the app- relatively uncommon in the world of Over-The-Air (OTA) updates, but convenient in this case. Using Interactive Disassembler (IDA) to sift through the firmware’s inner workings, he identified the functions that handle all basic operations, including displaying images on the screen, controlling the heating elements, and of course, beeping. From there, he modified the stock firmware image to include some malicious commands and ran an OTA update.

The mind-boggling part here is that not only was the firmware transmitted as unencrypted plaintext over unsecured WiFi, but the machine didn’t even require a user to confirm the update with a button press. With one quick reboot, the trap was set. The machine operated normally, while waiting for “Order 66,” causing it to turn all the heating elements on, spool up the built-in grinder, and beep. Constantly.

While a broken coffee machine seems relatively innocuous, there are some pretty significant lapses in hardware/firmware security here that, while avoidable, almost seem unnecessary in the first place. It makes us wonder- why does Mr. Coffee need a smartphone in the first place?

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