Perfecting The Solar Powered Web Server

October 8, 2018 by Tom Nardi 35 Comments

Running a server completely off solar power seems like it would be a relatively easy thing to do: throw up a couple of panels, tack on a charge controller and a beefy battery, and away you go. But the reality is somewhat different. Most of us hackers are operating on a relatively limited budget and probably don’t have access to the kind of property you need to put out big panels; both pretty crippling limitations. Doing solar on a small-scale is hard, and unless you really plan ahead your setup will probably be knocked out on its first cloudy day.

So when [Kris de Decker] wanted to create a solar-powered version of his site “Low-tech Magazine”, he went all in. Every element of the site and the hardware it runs on was investigated for potential power savings, and luckily for us, the entire process was written up in meticulous detail (non-solar version here). The server still does go down from time to time if the weather is particularly poor, but in general it maintains about 90% uptime in Barcelona, Spain.

The solar side of the equation is fairly simple. There’s a 50 watt photovoltaic panel charging a 12V 7Ah lead-acid battery though a 20A charge controller. With an average of 4 to 6 hours of sunlight a day, the panel generates 300 Wh of electricity in the best case scenario; which needs to be split between charging the battery and running the server itself.

As for the server, [Kris] chose the Olimex Olinuxino A20 Lime 2 in part because of it being open source hardware, but also because it’s very energy-efficient and includes a AXP209 power management chip. Depending on processor load, the Olimex board draws between 1 and 2.5 watts of power, which combined with charging losses and such means the system can run through two days of cloudy weather before giving up the ghost. A second battery might be added in the future to help improve the run time during low-light conditions, but for now its been working pretty well.

Perhaps the most interesting part of the whole project are the lengths to which the website itself was optimized to keep resource utilization as low as possible. Images are compressed using dithering to greatly reduce their file sizes, and the site eschews modern design in favor of a much less processor intensive static layout. There’s even a battery capacity display integrated into the page through some clever use of CSS. Even if you aren’t looking to set up your own sun worshiping website, there are tips here for building efficient web pages that could absolutely be put to use in other projects.

If you’re interested in solar projects, we’ve got you covered. From an open source charge controller to building DIY photovoltaic panels, there’s plenty of prior art you should find very…illuminating. Please clap.

Re-Using The LCD & Button Assembly From A Broken Inkjet Printer

September 11, 2014 by Rich Bremer 22 Comments

Inkjet printers are a dime a dozen. You probably have taken old printers apart to scavenge parts like motors, pulleys, belts, switches, linear rods, power supply, etc. These parts are easy to reuse in other projects, unlike the controller portion of the printer which not as easy to make use of. [Blaupause] has done something very interesting, and it probably ranks in the ‘extreme difficulty’ category for most tinkerers. He has taken the front panel off an otherwise non-working Canon Pixma inkjet printer and has figured out a way to interface with it.

The front panel of this printer has the standard buttons that you would find on any ole printer, but the Pixmas also has a small LCD screen. [Blaupause] has written a library for the Olimexino microcontroller that can communicate with and make use of the repurposed front panel. And the neat part of this project is that the front panel’s on-board processor does the heavy lifting when it comes to displaying images on the LCD screen or checking button states which frees up your microcontroller to do whatever else. Right now, the LCD screen can display bitmaps and supports image transparency. The library can not display video as of yet, but that option is being worked on.

[Blaupause] makes all his hard work available to the public on the project’s Sourceforge page. In addition to the library, he also includes printer panel pinouts and detailed information on how to communicate with the buttons and LCD screen. Video after the break…

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The Smallest ATtiny85 Based USB Board

May 7, 2014 by Nick Conn 41 Comments

Nanite 86

“Possibly the smallest ATtiny85 based ‘duino derivative”. Indeed! When Olimex announced the Olimexino 85s as the smallest Arduino ever, [Tim] took that as a challenge. His very small Arduino based USB devboard is quite a bit smaller than the Olimexino!

The Nanite 85 was carefully designed to be both small and functional. Not only is it 20% smaller than the Olimexino, but also sports a reset button! One of the coolest aspects of this design is that it has the same pinout and size as a DIP ATtiny85. This means that you can use the Nanite 85 for developing your code with the USB bootloader, and then you can directly replace it with a standard (pre-programmed) ATtiny85. The major downside to using this device over the aforementioned devices, is that it does not include a voltage regulator for powering the device via USB (or battery), the device is simply hooked directly to the 5V rail from the USB connector.

We can’t help but be impressed with this well-thought-out design. It is also easy to assemble since it uses larger surface mount components. If smaller components were used, even more features (such as a regulator) could be included. Do you have an even smaller USB Arduino? The race is on for the smallest Arduino ever!