Month: March 2014

Using An NRF24L01 For Air Bootloading

March 7, 2014 by 16 Comments

nrfboot_small

[Necromant] wrote a library to flash his microcontroller over an RF link using an NRF24L01 wireless communication module. The NRF24L01 is a cheap RF module that can be easily integrated into many microcontroller projects. Though there are Arduino libraries for driving the NRF24L01, [Necromat] decided to make a port of one with no Arduino dependencies.

The resulting bootloader fits into 4K of RAM flash with packet loss and recovery along with user-configurable hardware or software SPI. Programming speeds are not the highest, but [NecromatNecromant] believes this to be a property of the VUSB rather than the transfer rate from the NRF24L01 or the target microcontroller.

To program the target AVR chip, [NecromatNecromant] used another NRF24L01 module connected to his uISP dongle over USB.  Using a custom tool to interface with the uISP, the target board can be programmed in a similar fashion as avrdude. Check out the code for the ISP dongle and the AVR bootloader on his GitHub page.

I Can Fix The Space Station With A Metronome, A Metronome, A Metronome

March 7, 2014 by 42 Comments

ISS

If the space station were left to its own devices, the living quarters would get incredibly hot. There are computers, hardware, and six crew members, all generating heat that must be gotten rid of. To do this, there are two heat exchangers inside the station that take warm water, dump that heat to ammonia, and send that ammonia out to panels outside the station. On December 11, 2013, Loop A of the thermal control system shut down, putting the station one failure away from evacuation. Plans for a spacewalk were tabled, but the ground crew managed to fix this hardware failure by telling the astronauts to push buttons, a metronome, and a software patch.

The problem with Loop A of the Internal Thermal Control System was a flow control valve that regulated the amount of ammonia flowing through the heat exchange. Too much ammonia, and the station would be far too cold. Too little, and it would be too hot. This valve is electronically controlled and takes exactly 13 seconds to move from open to closed. The first attempt at fixing the problem was having ground crew send the command to open the valve and cut the power halfway through. This involved using a metronome app on a phone to send two commands 6.5 seconds apart. It worked, but not quite well enough.

The failure of the metronome technique led [Todd Quasny] to write a script to turn the ‘on’ and ‘off’ commands from the ground to the ISS with millisecond resolution. This meant the commands to control the valve could be sent with the right delay, but they weren’t received with the right delay. This is a problem that had to be fixed from the station’s computers.

To finally solve the problem, ISS software engineer [Steve Joiner] was called in to write a software patch for the thermal control system. This is spaceflight and writing software is a long a laborious process of testing and code reviews. Nevertheless, the team managed to write and upload a patch in just two days.

This patch gave controllers the ability to control the valve with a resolution of 100 milliseconds, good enough for very fine control of the thermal system, and all without requiring the massive amount of planning that goes into a spacewalk or resupply mission.

Ups to [Ed Van Cise] for this tip. If you’re curious about the headline….

SOAP: The Home Automation Router And Kickstarter Scam

March 7, 2014 by 141 Comments

How would you like a 7″ tablet with a Quad-core ARM Cortex A9 processor, USB 3.0, 32 GB of storage, 802.11ac, four ports of Gigabit LAN, Bluetooth 4.0, NFC, SATA, HDMI, built-in Zigbee and RFID modules, a camera, speaker and microphone, all for $170? Sound too good to be true? That’s because it probably is. Meet SOAP, the home automation router with a touchscreen, that’s shaping up to be one of the largest scams Kickstarter has ever seen.

There have been a few threads scattered over the web going over some of the… “inconsistencies” about the SOAP kickstarter, mainly focusing on the possibility of fake Facebook likes and Twitter followers. There’s also the question of their development process: they started building a router with an Arduino, then moved on to a Raspberry Pi, a Beaglebone, Intel Atom-powered Minnowboard, the Gizmo Board, PandaBoard, and Wandboard. If you’re keeping track, that’s at least six completely different architectures used in their development iterations. Anyone who has ever tried to build something – not even build a product, mind you – will realize there’s something off here. This isn’t even considering a reasonably accurate BOM breakdown that puts the total cost of production at $131.

The most damning evidence comes from screenshots of the final board design. These pics have since been removed from the Kickstarter page, but they’re still available on the Google cache. The SOAP team claims they’re putting USB 3.0 ports on their board, but the pics clearly show only four pins on each of the USB ports. USB 3.0 requires nine pins. A closer inspection reveals these screenshots are from the files for Novena, [Bunnie Huang]’s open source laptop.

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Turning A Router Into An Arduino Yún

March 7, 2014 by 13 Comments

yun

The Arduino Yún was the first of a new breed of Arduinos that added a big honkin’ Linux System on Chip to the familiar ATMega microcontroller and unique pin headers. It’s a surprisingly powerful system, but also very simple: basically, it’s just an Atheros AR9331 running Linux, an ATMega32u4 doing its Arduino thing, both connected by a serial connection. The Atheros AR9931 is also found in a router popular amongst hardware hackers. It really was only a matter of time before someone ported the Yun software to a router, then.

[Tony] took a TL-WR703N router and put OpenWRT on it. Turning this router into the Linux side of a Yún was a simple matter of uploading the Yún software to the root directory of the router and rebooting it. The Arduino side of the Yún is handled by an Arduino Mega connected to the USB port of the router. A quick update to Arduino’s boards.txt file, and a hacked together Yún is just a strip of duct tape away.

The Yún may not be extremely popular, but it does have a few interesting use cases. Maybe not enough to drop $70 on a board, but if you already have a WR703 router, this is a great way to experiment.

Thanks [Matt] for the tip.

Hanging Table Makes Room For Activities

March 7, 2014 by 15 Comments

F2N02EOHS18CAZE.MEDIUM

[Matt Silver] usually enjoys a cup of tea in the evening. Unfortunately, this habit can be frustrating and dangerous while sitting in bed. He rectified the problem by building this awesome space-saving table, which can be stored on the ceiling of all places! Depending on the supplies you might already have, this could be a relatively cheap build of about $40 or less. [Matt’s] using pine board for everything, but notes you could save time and money by re-purposing an existing coffee table. You will, however, need to make the ceiling frame to support it.

At the heart of this build is our favorite rope—Paracord 550. [Matt] used a single piece to tie the whole thing together, which can cause the table to lower crooked, but [Matt] found he can keep it level by putting a hand on it while it descends. You also get mechanical advantage from the pulleys this way! If you’re not crazy about the potential unevenness, you could redesign the pulley and eyelet layout to allow for four ropes to ensure a reliably horizontal surface.

Why not pair this idea with the portable electronics lab we shared a few days ago? You could have a full series of drop-down tool labs in your workshop. Think of all the space saving opportunities!

Face Tanner PCB UV Lamp Is So Bright, You Gotta Wear Shades

March 6, 2014 by 11 Comments

There may be nothing new under the sun when it comes to etching PCBs with UV light, but [Heliosoph] has brought finer control to a used face tanner he bought that now exposes his boards in ~50 seconds.

The original system allowed for exposure times from 1-99 minutes to be programmed in 1-minute increments. [Heliosoph] though it would be perfect as-is, but the lamp is so powerful that even one minute of exposure was too much. He hoped to find TTL when he opened the thing and was pleasantly surprised to discover a COP410L microcontroller and an MM5484 display driver. Unfortunately, the COP410L’s clock range is too small and he didn’t want to overclock it.

[Heliosoph] built a new board based on the ATMega328P with a salvaged 16×2 LCD, which he was able to easily integrate using the library that ships with the Arduino IDE. He then replaced the BT136 triac lamp switch with a solid state relay, conveniently isolating the electronics from mains power. He re-purposed the unit’s push buttons using the M2tklib, which supports a plethora of common menu functions.

If you need some help with the whole UV PCB etching process, you can’t go wrong with this tutorial from [CNLohr].

Building A Chainsaw Mill To Make Planks

March 6, 2014 by 20 Comments

Here’s a chainsaw hack that makes a lot more sense than the last one we shared…  It’s a setup you can build to help cut down logs into usable planks for your own projects!

Our guide on this tool hack is [BongoDrummer], who is the co-founder of a group in Wales called the Flowering Elbow, dedicated to imagining and making better futures by helping inspire people with inventions, encouraging project collaborations, and contributing to the community. We think he’s just a wee bit more knowledgeable than our previous grinder-chainsaw inventor…

[BongoDrummer] starts out with a proper note on safety, explaining accident statistics and offering up a refresher guide on proper chainsaw use. From there he gets right into the design and build of the mill. He’s chosen to use aluminum extrusion because it’s strong, light, and easy to work with—not to mention easy to assemble! Videos and more info after the jump.

Continue reading “Building A Chainsaw Mill To Make Planks” →