Mini Waterproof LED Lanterns Charge Without Wires

June 19, 2012 by Mike Nathan 23 Comments

inductive-charge-led-lights

If you’re in search of a flashlight that can stand up to the elements, or simply looking for an easy way to spruce up your pool for those hot summer nights, check out these rechargeable PVC LED lights. Inspired by a post in Make: Magazine featuring Indestructible LED Lanterns, [John Duffy] decided to take the project one step further.

While he liked Make’s iteration of the waterproof lantern, he thought it would be best to permanently seal the lights for maximum durability. Not satisfied with a one-use light, he equipped the PVC lanterns with a single rechargeable AA battery, step-up circuitry to drive the LED, and an inductive charging coil.

His floating, waterproof lights sport a slightly bigger footprint than their predecessors to house the extra electronics, but we think that’s more than a fair trade off considering they can be charged wirelessly.

Place your Digikey/Mouser/Jameco orders now and check out [John’s] how-to video – you just might get some of these built in time for the weekend!

[via HackedGadgets]

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STM32 Demo Code Carries Extra (hidden?) Copyrights

June 19, 2012 by Mike Szczys 31 Comments

Recently I started a repository that houses a template which may be used to compile STM32F0 projects with a GCC toolchain. There are two code packages from STM that I used when putting this together, the firmware for the Discovery board itself, and the Standard Peripheral Library for the chip family. I read the license agreements in the root of both packages and I think they’re quite fair. Basically the agreement is you can use them for any purposes as long as the code is only being used on STM hardware. Fair enough.

You can image I was quite upset so see a comment from a reader stating that I have a copyright violation with one of the files in the repo. It seems the linker script that is given as an example for Atollic’s TrueSTUDIO has it’s own extremely strict copyright:

** (c)Copyright Atollic AB.
** You may use this file as-is or modify it according to the needs of your
** project. Distribution of this file (unmodified or modified) is not
** permitted. Atollic AB permit registered Atollic TrueSTUDIO(R) users the
** rights to distribute the assembled, compiled & linked contents of this
** file as part of an application binary file, provided that it is built
** using the Atollic TrueSTUDIO(R) toolchain.

First off, I’m in violation just for posting the file in a repository. But read a bit deeper. Any code that is compiled with this using a GCC toolchain also breaks the copyright unless it’s Atollic’s toolchain.

My beef here is that STM is distributing this. Why? Why put something so restrictive into a software library with such an otherwise reasonable license? Surely there are many engineers at STM capable of writing a linker script that they could release under their own license which would work with TrueSTUDIO. And, it would have the added benefit of allowing other GCC-based toolchains a convenient (and legal) method of linking code.

So I’ve completely removed the file from the repository. If you were one of the ten people watching it on github, this had the unintended consequence of dumping your watch request. In the mean time I’m trying to learn how to write my own linker. This guide regarding Cortex-M3 linkers has been a great help. If you have the skills to contribute a working linker script, please issue a pull request or raise an issue over at github.

Multi-channel Analog Input Module Is A Good Jumping-off Point For Many Projects

June 19, 2012 by Mike Szczys 12 Comments

[Scott Harden] has already produced some projects which measure analog inputs. But he’s got plans for more and wanted a base system for graphing analog signals. You can see the small board next to his laptop which offers the ability to sample up to six signals and push them to a PC via USB.

The ATmega48 and a few supporting components are all you’ll find on that board. The USB connection is taken care of by an FTDI cable. He went that route because the cables are relatively cheap, easy to come by, and already have driver support on all the major operating systems. If you look at the screen you can see a window graphing one analog input in real-time. He wrote this in Python (which is once again a cross-platform tool) and it has no problem graphing all six inputs at once.

This is immediately useful as an upgrade to [Scott’s] ECG machine. His future plans include a Pulse Oximeter, EEG, and EEG.

Using Solar Cells To Track The Sun For Your Solar Cells (dawg)

June 19, 2012 by Mike Szczys 13 Comments

This solar panel tracks the sun using solar cells. It’s a pretty interesting technique, and can be done on the cheap.

The rectangular panels are doing the actual energy harvesting. The circular modules seen below are solar cells from some landscaping lights. They’re being used as sensors to help judge if the device is aimed directly at the sun. We’ve already seen this type of thing done with a quartet of light dependent resistors. In this case, if the negative leads for both landscaping lights are connected, a voltage may be read from the positive lead of each panel. If you measure that voltage, and use a rotating stand to adjust the position until the readings balance, you can be assured that your array is getting the optimal amount of sunlight.

[Gtoal] had been trying to drive motors directly from the output lines of these panels without success. We’re sure there’s a simple analog comparator circuit which would facilitate this. Grabbing a small microcontroller is another option (and some chips have an analog comparator built in).