Secret Serial Port For Arduino/ESP32

August 17, 2017 by 19 Comments

If you use the Arduino IDE to program the ESP32, you might be interested in [Andreas Spiess’] latest video (see below). In it, he shows an example of using all three ESP32 UARTs from an Arduino program. He calls the third port “secret” although that’s really a misnomer. However, it does require a quick patch to the Arduino library to make it work.

Just gaining access to the additional UARTs isn’t hard. You simply use one of the additional serial port objects available. However, enabling UART 1 causes the ESP32 to crash! The reason is that by default, UART 1 uses the same pins as the ESP32 flash memory.

Luckily, the chip has a matrix switch that can put nearly any logical I/O pin on any physical I/O pin. [Andreas] shows how to modify the code, so that UART 1 maps to unused pins, which makes everything work. it is a simple change, replacing two parameters to a call that — among other things — maps the I/O pins. You could use the technique to relocate the UARTs to other places if you choose.

If you want to learn more about the ESP32, we covered a good set of tutorials for you to check out. Or if you just want a quick overview, you can start here.

Living On Mars: The Stuff You Never Thought About

August 17, 2017 by 123 Comments

In The Martian we saw what kind of hacking was needed to stay alive for a relatively short while on Mars, but what if you were trying to live there permanently? Mars’ hostile environment would affect your house, your transportation, even how you communicate. So here’s a fun thought experiment about how you’d live on Mars as part of a larger community.

Not Your Normal House

Mars One living units under regolith
Mars One living units under regolith, Source video

Radiation on Mars comes from solar particle events (SPE) and galactic cosmic radiation (GCR). Mars One, the organization planning one-way trips to Mars talks about covering their habitats in several meters of regolith, a fancy word for the miscellaneous rocky material covering the bedrock. Five meters provides the same protection as the Earth’s atmosphere — around 1,000 g/cm2 of shielding. A paper from the NASA Langley Research Center says that the largest reduction comes from the top 15 to 20 cm of regolith. And so our Mars house will have an underlying structure but the radiation protection will come from somewhere between 20 cm to a few meters of regolith. Effectively, people will be living underground.

On Earth, producing water and air for your house is not something you think of doing, let alone disposing of exhaled CO2. But Mars houses will need systems for this and more.

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Multiple Monitors With Multiple Pis

August 17, 2017 by 26 Comments

One of the most popular uses for the Raspberry Pi in a commercial setting is video walls, digital signage, and media players. Chances are, you’ve probably seen a display or other glowing rectangle displaying an advertisement or tweets, powered by a Raspberry Pi. [Florian] has been working on a project called info-beamer for just this use case, and now he has something spectacular. He can display a video on multiple monitors using multiple Pis, and the configuration is as simple as taking a picture with your phone.

[Florian] created the info-beamer package for the Pi for video playback (including multiple videos at the same time), displaying public transit information, a twitter wall, or a conference information system. A while back, [Florian] was showing off his work on reddit when he got a suggestion for auto-configuration of multiple screens. A few days later, everything worked.

Right now, the process of configuring screens involves displaying fiducials on each display, taking a picture from with your phone and the web interface, and letting the server do a little number crunching. Less than a minute after [Florian] took a picture of all the screens, a movie was playing across three weirdly oriented displays.

Below, you can check out the video of [Florian] configuring three Pis and displays to show a single video, followed by a German language presentation going over the highlights of info-beamer.

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Krave antweight battlebots

Krave Antweight Robot Gets Eaten And Stays Alive

August 17, 2017 by 8 Comments

The battle’s are done and the results are in — [AltaPowderDog]’s, aka [Carter Hurd],  cardboard and foam armor, lightweight Krave robot beat its metal cousins in 2016 and fared well in 2017. How did a cardboard Krave cereal box and foam board robot do that you ask? The cardboard and foam outer structure was sliced, smashed and generally eaten while the delicate electronics, motors and wheels remained buried safely inside.

We covered the making of his 2016 version but didn’t follow-up with how it fared in that year’s Illinois Bot Brawl competition. As you can see in the exciting first video below, despite suffering repeated severe damage to its armor, it won first place in the 1 lb Antweight category!

Battery and RC receiver
Wheels, motors and speed controller
Finished Krave robot

For 2017 he made another one but managed to halve the weight — and so he made two of them! By starting them both within a twelve-inch by twelve-inch area, they were allowed to fight as a team. How did he make it lighter? Partly it was done by doing away with the ability to lift the metal lip in front, the wheels were reduced from four to two, and a smaller servo was used for opening and closing the mouth. The full build video is shown below along with a video of the 2017 battles wherein he won seventh place.

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Wield The Power Of Molten Metal

August 16, 2017 by 16 Comments

[TheBackyardScientist] at it again with another super villain-esque demonstration of gadgetry: a liquid metal squirt gun.

The squirt gun has a compressed air tank like most others — more on that later — but to fire its primary ammunition, a nozzle that connects directly to an air compressor is needed. Again, like most guns of this nature, air is forced into the gun’s reservoir, displacing the pewter and expelling it out the gun’s barrel. Yes, pewter.

Working around the heat tolerances of thread seal tape, pewter has a low enough melting point that an airtight system is preserved — plus it’s really cool to fire a stream of liquid metal. The ammunition is made from pewter ware melted down and cast into pucks. These pucks are stacked into the gun’s magazine, melted with a propane torch and carefully loaded into the gun.

The built-in compressed air tank lacks the oomph to push out the pewter — hence the air compressor, but any lighter liquids or condiments are fair game for rapid-fire exercises. Yes, condiments.

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A Great Way To Make Quick And Easy Knobs

August 16, 2017 by 34 Comments

Here’s a great way to quickly and easily make attractive and functional knobs with no tools required. All you need is some casting resin (epoxy would do in a pinch), a silicone mold intended for candy, and some socket head bolts. With the right preparation and a bit of careful placement and attention, smooth and functional knob ends are only minutes away. Embedded below is a short video demonstrating the process.

These may not replace purpose-made knobs for final products, but for prototypes or to use around the shop on jigs, clamps, or furniture they certainly fit the bill. With a layer of adhesive fabric or rubber, they might even make serviceable adjustable feet for low-stress loads.

This technique could be extended to reproducing broken or missing dakaware or bakelite knobs. This, of course, would require an original, unbroken knob and a small silicone mold, but it’s still a project that’s well within the capabilities of the garage-bound hacker.

While we’re on the subject of knobs, don’t forget we’ve seen an excellent method of repairing knobs as well.

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Bringing A 50 Watt Laser Cutter To Life

August 16, 2017 by 22 Comments

This is the future and we live in a world of 3D printers and laser cutters. Have you ever pondered the question of getting yourself a laser cutter? Well [Erich Styger] just landed a 50 Watt Laser Cutter from AliExpress and has written up a detailed guide to his experience.

[Erich] had been wrestling with the idea of buying one for himself for some time but was put off by the difficulty in their operation. This changed when [Scorch] published the K40 Whisperer control software which allows for better control over these machines. With the hopes of an interesting weekend project, [Erich Styger] took a leap of faith and spent $900 on a model 4040 laser cutter.

In his blog, he goes through the steps in setting up the machine as well as calibrating the laser. With a plethora of images and a detailed look at each aspect of the leveling and testing, [Erich Styger] had a weekend well spent and a working K40 laser cutter for his workshop. But perhaps the more valuable part of the stories is the overall experience.

It was not a “what you see is what you get” order, but it did turn out to be a hacker’s “what you want is what you get” adventure. The machine didn’t look the same as the picture, it came with a burned CD-R with a box full of small parts (in addition to separate shipment of a USB thumb drive and silicone sealant), and there were some mechanical touchups plus a stuck switch requiring reassembly. He has done an excellent job of documenting from order to test-runs and the photos alone are worth taking a look.

Adding value to inexpensive laser cutters in an often-featured project around here. If you are looking for more details on these wonderful machines, be sure to check out more tales of Cheap Laser Cutters and our coverage of the K40 Whisperer software launch from last month.