150,000 Members Strong, Hackaday.io Flies Past Another Milestone

We’re growing so fast that soon your mom will be on Hackaday.io. That’s fine, everyone who loves hardware is welcome. 150,000 members have made Hackaday.io a home for their creativity — looking for inspiration in the work of others, sharing successes and temporary failures, and building their dream team to take on amazing new challenges. There is no place in the world that can come close to matching the Open Hardware ecosystem that is Hackaday.io.

What is in that one number, 150k? It is a monumental chunk of a much bigger picture: the thriving Hackaday ecosystem that spans from staking down your own workshop full of projects and skills, to following the editorial pulse of hardware used in new and creative ways. Looking over the last twelve months on all of the Hackaday sites we’ve seen about 18.5 Million visitors and registered nearly 85 Million views. Hackaday is not a passive community. We all have an insatiable hunger to delve into the next big trick, and to celebrate the accomplishments that made it happen.

Want to find a new and unique way to use the tech you find most interesting? Your leap forward needs input to pollinate the idea. Hackaday has a critical mass of hackers, designers, and engineers waiting with excitement to hear and help out in exploring and expanding the frontier. These interaction are what has packed Hackaday.io with interesting people. Most would say: I came for a specific hack or to see what a particular hacker was up to, but then I felt at home and decided to stick around and share what I’ve spent way to much time doing (but I wouldn’t have it any other way).

As we continue to knock down one membership milestone after another I want to thank you all for being involved, for valuing the free and open sharing of information and ideas, and for sharing your own time and talent. You are what moves this community of hardware hackers to dizzying heights of excellence and awesome.

This is all too good to be a secret. Talk to your hardware-loving friends, colleagues, family, and acquaintances and invite them to Hackaday.io if they’re not already with us.

What Could Go Wrong: Asynchronous Serial Edition

It’s the easiest thing in the world — simple, straightforward serial data. It’s the fallback communication protocol for nearly every embedded system out there, and so it’s one that you really want to work when the chips are down. And yet! When you need it most, you may discover that even asynchronous serial can cost you a few hours of debugging time and add a few gray hairs to your scalp.

In this article, I’m going to cover most (all?) of the things that can go wrong with asynchronous serial protocols, and how to diagnose and debug this most useful of data transfer methods. The goal is to make you aware enough of what can go wrong that when it does, you’ll troubleshoot it systematically in a few minutes instead of wasting a few hours.

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Gawking Text Files

Some tools in a toolbox are versatile. You can use a screwdriver as a pry bar to open a paint can, for example. I’ve even hammered a tack in with a screwdriver handle even though you probably shouldn’t. But a chainsaw isn’t that versatile. It only cuts. But man does it cut!

aukAWK is a chainsaw for processing text files line-by-line (and the GNU version is known as GAWK). That’s a pretty common case. It is even more common if you produce a text file from a spreadsheet or work with other kinds of text files. AWK has some serious limitations, but so do chainsaws. They are still super useful. Although AWK sounds like a penguin-like bird (see right), that’s an auk. Sounds the same, but spelled differently. AWK is actually an acronym of the original author’s names.

If you know C and you grok regular expressions, then you can learn AWK in about 5 minutes. If you only know C, go read up on regular expressions and come back. Five minutes later you will know AWK. If you are running Linux, you probably already have GAWK installed and can run it using the alias awk. If you are running Windows, you might consider installing Cygwin, although there are pure Windows versions available. If you just want to play in a browser, try webawk.

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Mosaic Palette: Single Extruder Multi-Color and Multi-Material 3D Printing

Lots of solutions have been proposed and enacted for multi-color and multi-material 3D printing, from color mixing in the nozzle to scripts requiring manual filament change. A solution proposed fairly early on was to manually splice the filament together, making a custom spool. The printer would print as normal, but the filament would change color. This worked pretty well, but it was tedious and it wasn’t entirely possible to control where the color change happened on the model.

You’ll find some examples of the more successful manual splicing hacks in the pictures below. Scroll down a bit further to find our interview with Mosaic Manufacturing at Bay Area Maker Faire 2016. They have a new product that automates the filament splicing process with precision as the ultimate goal. It unlocks a single extruder printer to behave like a multi-extruder model without stopping and starting.

Mosaic pulled off a very difficult combination of two methods mentioned above. Their flagship product is a machine they’ve dubbed, “Palette”. It’s an automatic filament splicer. Up to four different filaments can feed into Palette, and it will splice them at determined intervals. This would be cool by itself, if only to save the tedium of splicing and winding a custom spool by hand.

The real killer app with Palette, however, is the software that runs alongside it. Palette can take the GCODE output of any properly prepared multi material file from any slicer, and then precisely combine and splice the filament. This can feed into any printer without modifying it, aside from sticking an encoder somewhere in the filament path. The results are indistinguishable from a dual, or quad extruder set-up.

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Hackaday Links: June 19, 2016

Wait a minute. We’re almost through June and we haven’t seen anyone’s ‘DIY air conditioning’ setup. Oh the shame! How could we ever argue about thermodynamics otherwise? Here’s some copper tubing wrapped around a fan. Does it make sense? Assuming you’re making the ice (or cold whatever) in a room separated from the crappy air con, and you don’t have to pay for electricity (or ice), and you don’t mind hauling buckets of ice every few hours, yes. It’ll work. Now we can argue if you should put salt in the ice water…

I know I mentioned this in last week’s links post, but [Arsenijs]’s Raspberry Pi project is growing by leaps and bounds. He already has more than 33 followers to this project (awesome!) and 3.3k views on his project page. Not only is it climbing in popularity, but this is also a great use for the Raspberry Pi. You don’t see projects like this come around very often.

The Goliath is a quadcopter powered by a lawnmower engine. It was an entry in the first Hackaday Prize, but the project literally never got off the ground. There’s now a Mk. II version in the works. Goliath is getting a new frame made out of aluminum tube and rivets. There’s going to be ducts on the props, and this version might actually fly.

You did know Hackaday has it’s own Hackaspace, right? Technically it’s the Supplyframe Design Lab, but there are still a few skull ‘n wrenches hidden in the rafters. The Design Lab is hosting an open house this week on June 23rd, and the design lab residencies will begin July 1st. If you have an idea for something you’d like to build, here’s the residency application.

The LimeSDR is a powerful next generation software defined radio that’s currently on CrowdSupply The crowdfunding campaign ends in just a few days. It’s a very impressive tool, able to send and receive anything from 100 kHz to 3.8 GHz.

Last week one of our writers posted a review on the Monoprice MP Select Mini 3D printer. This printer is becoming stupidly popular, and Monoprice has depleted their inventory twice since then. I’ve been watching the product page for this printer for a while now, and here’s what happens: 1) Printer is out of stock, with an ETA of about a month in the future. 2) Printer is still out of stock, ETA is a few days away. 3) Monoprice has this printer in stock. This cycle seems to repeat every week or so.

Arduino Raycasting. When you think of raycasting, you probably think about Wolfenstein 3D, or other barely 3D games. You don’t need a powerful CPU like a 386 for raycasting – you can do it on an Arduino. The display is a 32×16 matrix of LEDs, control is through a Wii Nunchuck, and yes, head-bobbing is implemented. Here’s a video.

Hacklet 112 – Skateboard Projects

Skateboarding is a sport that was born of hacking. The identity of the person who first nailed roller skate wheels to a board with a milk crate box is lost to history. Those crate scooters were a staple of the 1940’s and 1950’s neighborhoods. Everyone built their own scooter, so the designs evolved. Eventually the milk crates disappeared. At some point, surfers realized that they could use these wheeled boards to surf the concrete jungle. Things just took off from there. Skateboarding is now a multi-billion dollar industry, but at its heart there are still hackers trying out new designs. This week’s Hacklet is all about skateboarding projects.

long1We start with [brian.rundle] and Electric Longboard. [Brian] built his board using trucks and mechanical parts from a DIY skateboard online shop. The motor is a brushless outrunner R/C plane motor from HobbyKing. Batteries are of the LiPo variety. An Arduino Nano provides the PWM signal which drives the Electronic Speed Control (ESC). Throttle control is via RF link using the popular Nordic Semi NRF2401. [Brian] is focusing on building a safe skateboard. He designed it to carry two batteries, though only one is in use at a time. Rather than use a switch, he’s created a fool-proof system with arming plugs and jumpers. Each battery has its own arming plug. There is one jumper, so only one battery can be connected to the board at a time.

brake1Next up is [suiram21] with Longboard Brake. Downhill longboarding can be a dangerous sport. Running downhill at 40MPH or more with no brakes makes for quite an adrenaline rush. [suiram21] loves longboarding but wanted the safety of having a brake if and when he needed it. He started with a Onda board, which is a longboard with large diameter wheels. He 3D printed brackets for a cable actuated braking system. The brake is activated by stepping on a lever at the rear of the board. A lever presses a bicycle brake pad into the inside edge of the tire. This brings the board to a gentle stop. [suiram21] is thinking of adding a second brake to the other wheel to increase braking authority.

speedo1Next we have [edbraun] with Skateboard Speedometer by inventED. [edbraun] wanted to know how fast he was going. A GPS would work, but GPS signals are often blocked in cities. A more accurate way to gather speed data is directly from the wheels. Two tiny magnet plugs are placed in holes drilled in the wheel. A hall effect sensor detects the magnets and passes this data on to an Arduino Pro Mini. Once the speed is calculated, it’s sent to a Bluetooth radio. [edbraun’s] Android phone receives the data and displays current speed and total distance traveled. The speedometer and its slick 3D printed case almost hide between the trucks and the board itself. Nice work [edbraun]!

josh1Finally we have Hackaday alum [Josh Marsh] and EV Commuter Longboard. [Josh] uses an electric longboard for his daily commute. His project is an excellent overview and tutorial on building an electric skateboard from scratch. Like many others, [Josh] utilizes R/C Airplane brushless motors and speed controllers. An Arduino or similar microcontroller is all you need to drive these devices. For batteries, [Josh] loves LiPo packs. Long form six cell affairs provide 22.2 Volts with a capacity of 5000 mAh or more. Plenty of power for carving your way to work!

If you want to see more skateboard projects, check out our new skateboard projects list! If I missed your project, don’t be shy, just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Ask Hackaday: Whatever Happened to LED Light Sensors?

If you’re a long-time Hackaday reader like we are, you’ll certainly remember a rash of projects from around ten years ago that all (mis-)used an LED as a light sensor. The idea wasn’t new, but somehow it made the rounds and insinuated itself into our collective minds. Around the same time, a cryptographic cipher with an exceptionally small memory footprint was also showing up in hacker projects: TEA (Tiny Encryption Algorithm).

This old project by [Marcin Bojanczyk], [Chris Danis], and [Brian Rogan] combines both the LED-as-light-sensor meme and TEA to make a door-entry keyfob that works over visible light. And they do so using almost nothing — a few LEDs and just over 2Kb of code. It’s pretty sweet.

Which brings us to the question: where are they (LED-sensors and TEA) now?

ledtouch_photoLED-as-light-sensor was just cool. We certainly loved the idea back in 2006. But [Forrest Mims] had been using the phenomenon for decades back then. It certainly makes sense when you’re trying to squeeze as much as possible out of as little as possible, or when budget is a main concern and you just can’t afford an extra photodiode.

But our own experience with LEDs as light sensors is that the results are extremely variable across different LEDs. Code that works with water-clear red LEDs might not work with the ones that come in red-tinted plastic, for instance. Is that why they went extinct?
4746123271_7888160588Similarly, the TEA family of ciphers showed up in a bunch of projects around this time, from the badge for the HOPE conference in 2010 to a widely used RFM12B radio library. There are a couple of attacks on XXTEA, but they only affect reduced-round versions of the cipher, and rely on a tremendous amount of intercepted data — more than we’d see in a home-automation network over years.

Over the last five years or so, there’s been a lot more Internet of Things, which means using standard Internet-style encryption methods (AES and so on) that are widespread on non-memory-constrained computers. Is that what happened to XXTEA?

Anyway, we got tipped off to a project that combined a few of our favorite (old) ideas in one, so we thought that we’d share. Thanks [Blue Smoke] for the walk down memory lane. Any of you out there keeping the flame(s) alive? Have you used sensing LEDs or XXTEA? Are those projects still going, or do you have any future projects planned with these tricks still up your sleeve? Let us know in the comments below.