Create Cheap Philips Hue Compatible Devices

The Philips Hue range is a great way to add wirelessly controllable lighting to your home, but the protocol is proprietary which makes it difficult to add our own custom hardware. [Peter] found a way to create his own Hue compatible devices based on cheap JN5168 modules that are able to connect to the Hue bridge. This means you can roll out your own lamps using cheap RGB or White LEDs, a power supply and the JN5168 Zigbee Light Link module.

He started off by trying to clone a Zigbee Light Link device to a MeshBee — Seeed studio’s open source Zigbee Pro module based on the NXP JN5168. Even though the MeshBee used the same device as a Hue lamp, it would not connect to the Hue bridge. But another clone lamp called Innr that he purchased from the local hardware store did connect quite easily. Using NXP’s open source tools, he was able to download the flash and EEPROM contents from the Innr and copy them to the MeshBee which did the trick.

After the EEPROM transfer trick, he figured out how to modify the two keys used for the ZigBee protocol — one for Home Automation and the other for the Light Link. With this final discovery he is able to take the ZigBee Light Link demo project, edit it using Beyond Studio, and then load the binaries on the MeshBee device so it can connect to the Hue bridge.

All of this work culminates in two custom firmware binaries; one for white dimmable lights and another for RGB dimmable ones. It even runs on these cheap JN5168 breakout kits he found for a few bucks. With all of the software taken care of, and having cheap ZigBee Light Link compatible modules on hand, building low cost Hue compatible lights becomes pretty straight forward.

Thanks [wind-rider] for the tip.

Where Are The Autonomous Lawnmowers?

It’s impossible to know when society began to manicure its front lawns. Truth be told — cutting the grass was, and still is a necessity. But keeping the weeds at bay, trimming, edging and so forth is not. Having a nice lawn has become a status symbol of modern suburbia all across the globe. When the aliens arrive, one of the first things they will surely notice is how nice our front lawns are. This feature of our civilization could have only been made possible with the advent of specialized grass-cutting machines.

reel mower
Reel Mower [Public Domain]
It could be argued that the very first lawnmowers were live stock. The problem was they were quite high maintenance devices and tended to provide a very uneven cut, which did not bode well for families striving for the nicest front lawn on the dirt road. Coupled with the foul odor of their byproducts, the animals became quite unpopular and were gradually moved out of site into the back yards. Other solutions were sought to maintain the prestigious front yard.

The first mechanical lawnmower was invented in 1830 by a man named Edwin Budding, no doubt in an effort to one-up his neighbor, who still employed a Scythe. Budding’s mower looked much like today’s classic reel mowers, where a rotating cylinder houses the blades and rotates as the mower is pushed forward. Budding was granted a patent for his device by England, much to the dismay of his fellow neighbors — most of whom were forced to buy Budding’s mower due to the fact that everyone else in the neighborhood bought one, even though they weren’t actually needed.

By the early 1930’s, the cold war started by Budding and his neighbor had spread to almost every front yard on earth, with no end in sight. Fast forward to the modern era and the lawn and garden market did 10 billion in sales in 2014 alone. Technological advances have given rise to highly advanced grass-munching machines. For smaller yards, most use push mowers powered by a single cylinder IC engine. Many come with cloth bags to collect the clippings, even though everyone secretly hates using them because they gradually fill and make the mower heavier and therefore more difficult to push. But our neighbors use them, so we have to too.  Larger yards require expensive riding mowers, many of which boast hydrostatic transmissions, which owners eagerly brag about at neighborhood get-togethers, even though they haven’t the slightest clue of what it actually is.

Us hackers are no different. We have front lawns just like everyone else. But unlike everyone else (including our neighbors) we have soldering irons. And we know how to use them. I propose we take a shot-across-the-bow and disrupt the neighborhood lawn war the same way Budding did 85 years ago. So break out your favorite microcontroller and let’s get to work!

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Using A Jewelry Kit To Resin-Encase Electronics

clear-cast-squareSome of us have looked at clear resin jewelry casting kits online and started to get ideas. Hackaday’s own [Nava Whiteford] decided to take the plunge and share the results. After purchasing a reasonably economical clear resin jewelry casting kit from eBay, a simple trial run consisted of embedding a solar lantern into some of the clear resin to see how it turned out. The results were crude, but promising. A short video overview is embedded below.

The big hangup was lack of a proper mold. [Nava]’s attempt to use a plastic bag and a cup as an expedient stand-in for a proper mold was not without its flaws, and the cup needed to be broken before the cured resin could be removed. Despite this, the results were good; the mixing needed careful measurement and the curing process was lengthy but the cured resin is as attractive as the advertisements promise. Mixing introduced many air bubbles into the mixture, but most of them seemed to disappear on their own during the curing process. The results of this quick test may not be pretty, but the resin seems to have held up its end of the bargain and delivered the expected smooth, clear finish.

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DIY 3D Slicer Is A Dynamo

We all know that hacker that won’t use a regular compiler. If he’s not using assembly language, he uses a compiler he wrote. If you don’t know him, maybe it is you! If you really don’t know one, then meet these two. [Nathan Fuller] and [Andy Baldwin] want to encourage you to write your own 3D slicer.

Their post is very detailed and uses Autodesk Dynamo as a graphical programming language. However, the details aren’t really specific to Dynamo. It is like a compiler. You sort of know what it must be doing, but until you’ve seen one taken apart, there are a lot of subtleties you probably wouldn’t think of right away if you were building one from scratch.

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Beefy 100 Amp Electronic Load Uses Two MOSFETs

[Kerry Wong] had some extreme MOSFETs (IXTK90N25L2) and decided to create a high current electronic load. The result was a two-channel beast that can handle 50 A per channel. Together, they can sink 400 W and can handle a peak of 1 kW for brief periods. You can see a demo in the video below.

An electronic load is essentially a load resistor you can connect to a source and the resistance is set by an input voltage. So if the load is set to 10 A and you connect it to a 12 V source, the MOSFET should look like a 1.2 ohm resistor. Keep in mind that’s 120 watts–more power than a common incandescent light bulb. So you are going to need to carry some heat away.

The circuit is pretty simple. The FETs accept a voltage on their gates that sets them to look effectively like a resistor that varies with the voltage. A very small source resistor develops a voltage based on current (only 75 mV for a 50 A draw). That voltage feeds a comparator which generates the gate voltage after looking at the input control voltage. Each millivolt into the comparator translates to an additional 1.33 A through the load.

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Looking Back At QRP Transmitters

When you get to a certain age, you get unsettled by people calling “your” music oldies. That’s how a few of us felt when we saw [Mikrowave1’s] video about Retro QRP – Solid Gold Years (see below). “QRP” is the ham radio term for low power operation, and the “solid gold” years in question are the 1960s to 1980. The videox has some good stuff, including some old books and some analysis of a popular one-transistor design from that time. He even tries a few different period transistors to see which works best.

[Mikrowave1] talks about the construction techniques used in that time frame, old transistors, and some vintage test equipment. You can even see an old ARC-5 command receiver in use to listen to the transmitter. These were made for use in military aircraft and were very common as surplus.

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Reverse Engineering The Smart ForTwo CAN Bus

The CAN bus has become a defacto standard in modern cars. Just about everything electronic in a car these days talks over this bus, which makes it fertile ground for aspiring hackers. [Daniel Velazquez] is striking out in this area, attempting to decode the messages on the CAN bus of his Smart ForTwo.

[Daniel] has had some pitfalls – first attempts with a Beaglebone Black were somewhat successful in reading messages, but led to strange activity of the car and indicators. This is par for the course in any hack that wires into an existing system – there’s a high chance of disrupting what’s going on leading to unintended consequences.

Further work using an Arduino with the MCP_CAN library netted [Daniel] better results, but  it would be great to understand precisely why the BeagleBone was causing a disturbance to the bus. Safety is highly important when you’re hacking on a speeding one-ton metal death cart, so it pays to double and triple check everything you’re doing.

Thus far, [Daniel] is part way through documenting the messages on the bus, finding registers that cover the ignition and turn signals, among others. Share your CAN hacking tips in the comments. For those interested in more on the CAN bus, check out [Eric]’s great primer on CAN hacking – and keep those car hacking projects flowing to the tip line!