Archive for the ‘Show-n-Tell’ Category

The Arachnio is something I’ve been working on for a few months, and it’s now up on Kickstarter! The subject line is the elevator pitch — it’s the first Arduino Micro variant with onboard WiFi, via the increasingly popular ESP8266. It’s pin and software compatible with the existing Arduino Micro, and only slightly larger to accommodate the antenna. Naturally, it’s entirely open source (unlike other Arduino variants with on-board WiFi, such as the Yun).



The Arachnio

The Arachnio

Putting WiFi together with the Arduino, especially in a small, low power package, is a really natural fit. For example, every Arduino-powered robotics or LED project is made immensely cooler by having the capability to control it from your smartphone baked right in.

Since the Arachnio is small and low power, it also makes a great brain for a remote sensor. The fact that it’s an Arduino variant makes the programming simple and the wealth of on-board peripherals make it straightforward to connect most common sensors. WiFi lets your remote sensor connect to your phone or tap into the Internet to get the data back to you.

Including both the ESP8266 and the 32u4 on a single board provides a much more useful package than either one alone. The capabilities of the ESP8266 and the 32u4 complement each other nicely. Here are some of the advantages of the Arachnio over an ESP8266 module alone:

  • More GPIO — The Arachnio has more than twice as many GPIO pins available as any ESP8266 module.
  • More ADC — The Arachnio has twelve usable analog to digital channels versus a single channel for an ESP8266.
  • Hardware PWM
  • Dedicated hardware I2C and SPI interfaces
  • Full Arduino library compatibility 
  • Native USB — The Arachnio’s ATmega32u4 provides a full speed hardware USB interface. The Arduino environment provides libraries that make the USB function as a serial port, a mouse, or a USB keyboard.
  • Breadboard compatible — The Arachnio’s headers are on 0.1″ centers and narrow enough to fit into standard breadboards with room to plug jumpers in on both sides.

And of course the ESP8266 provides WiFi and, for more advanced users, a more powerful processor to use for more computationally intensive tasks.

All of the vital statistics can be found on the Arachnio product page.

I decided I also needed a couple of expansion boards available immediately in order to really make it sing. The first is of course a prototyping board, the ArachnoProto.

ArachnoProto with Arachnio and supports

ArachnoProto with Arachnio and supports

The ArachnoProto is designed to fill the same role as an Arduino protoshield. It has two large prototyping areas, a programming header,  mounting holes for 3mm screws, two LEDs and a pair of push buttons.

You can tell this is a prototype because the board house managed to mess up my logo on the board.

There’s also another less obvious feature here, which is that this board has been assembled with bottom-entry headers on the underside. The upshot of this is that the assembled Arachnio + ArachnoProto is much thinner than with conventional headers. These headers are included with every ArachoProto.

The Arachnode is designed to give users a way to quickly build flexible and independent sensor and network nodes. It has a solar battery charger, a real time clock, a microSD card slot, and an optional crypto module.

I just got a new release candidate board which has some tweaks arising from the testing we’ve been doing, mostly to improve fit and clearances. This is the first one that’s really feature complete, since I’ve been focusing on the Arachnio rather than the Arachnode for most of my development. I haven’t had time to assemble the new ones, but here’s the bare PCB:

Arachnode bare board

Arachnode bare board

One of the things I’ve enjoyed doing that I wish more Kickstarter creators would do is post Instructables for the Arachnio. I’ve only got two of them up so far, but they address questions that people have asked me about using the Arachnio.

Please don’t forget to back the Arachnio on Kickstarter so we can make it a reality!


Thanks to gorgeous weather here in Seattle yesterday, I was able to get some great pictures of the ArachnoProto and Arachnode prototypes.








In our last post we discussed the goal and methods around capturing the birefringence found in frozen soap bubbles.   The good news is that we established a solid method for capturing birefringence, but so far have yet to see any real noticeable birefringence on soap bubbles.

Along the way we did capture some amazing photos of soap bubbles in several different states of frozen, and finally just shot some images of just ice crystals forming.  We have some videos of the growth of crystals which we might post later.

In order to capture images such as these, you need to polarizing sheets.   One covers your light source (flash, led, etc), the other over your camera. It is important that the polarizing sheet is the last optical element before the subject you wish to photograph.

First, more photos of “ice crystals we really wished showed birefringence “.  We have a few theories about why this doesn’t work (including: thin film from glycerine causing scatter, too many layers of ice, etc).  At this point it’s still unknown, any comments welcomed!  The good news is that the soap is showing it’s lovely colors!

Well, that sure was neat, but we didn’t really get the birefringence in water crystals we wanted. So it was time to just try old fashioned ice crystals and liquid nitrogen. The results where spectacular:

Here’s where it got interesting. By rotating the polarizing film different parts of the crystals would show birefringence based on the changing angles interacting with each other.

Frozen bubbles!

Posted by 3ricj on 3 February 2013

Transparent solids can show birefringence when they are under mechanical stress. This stress can be present in a part after it’s manufactured (in the case of plastic) or present due to thermal expansion. You can view these birefringence patterns if you view it between two crossed polarizers.

These patterns can also be found in ice. I decided, on a whim, that would attempt to photograph birefringent (cross polarized) crystals in frozen soap bubbles. This is what is hopefully going to be short set of posts with attempts to do so.

For starters, making frozen bubbles has it’s own challenges. When air cools, it compresses. This would likely lead to a fracture of the bubble. The first attempt to make frozen bubbles confirmed this – if you inflate a bubble using (warm) air from your lungs, it pops the moment it gets close to something cold. In this case, we tried this with a pool of liquid nitrogen – –  it fractured well before hitting the liquid. We did manage to make some ‘broken half bubbles’, which floated around on the gaseous nitrogen. I don’t have any photos of this, but let’s just say it didn’t work so well. After some trials and tribulations we developed the following method to make frozen bubbles:

  • Take a short (12″) copper pipe
  • dip one end into a “bubble solution”, adding additional glycerin may help.
  • Make sure that there is bubble solution coating the outside of the pipe; a thin film will work fine.
  • Submerge the other end into a cup of liquid nitrogen.
  • The warm copper will cause a phase change in the nitrogen, which will inflate the bubble with chilled nitrogen.
  • Before it pops, gently shake the pipe such that bubble ‘slides’ down to the pipe.
  • Take the pipe and hold it carefully over a pool of liquid nitrogen. There will be a thermal gradient there which enables the bottom of the bubble to freeze.
  • With some luck and skill, you can “thaw” and “refreeze” your bubble many times before it bursts.

Here are some photos of our first round of testing.  At the time we didn’t have a good setup for capturing the birefringence in the crystals then we ran out of liquid nitrogen!. We will have to try again. On the next post I’ll provide more information about how to capture birefringence using a camera.

A nitrogen filled bubble:

Frozen bubbles!

A shot of an old fashioned ice-cube under cross polarization (you can see birefringence!!):

Drip Drip goes the funding.

Posted by 3ricj on 30 August 2012

Our friends over at shift labs are seeking funding for one of their projects. Ya’ll should go fund their product they are building for the developing world. No lasers, but it’s still bad-ass. Even if they are excessively smiley on video. Go give them money. kthx.

Photonic Beam: Results

Posted by ratha on 15 August 2012

The laser was successfully deployed at Toorcamp. We operated it on Friday and Saturday nights (August 10 and 11, 2012). Design and construction of the laser is documented in previous posts here and here.

Here is the laser in operation:

H1kari took the following amazing photo of the laser punching through above the fog:

Joe FitzPatrick took this futuristic photo proving once and for all that we implement science fiction:

The Yurt

The yurt on which the laser was mounted was built by Ratha in 2008. It provided a stable, 8′ tall platform (above eye level) and it made the phrase “laser yurt” possible.

Safety interlocks

We had a bit of trouble with the motion sensors detecting motion *outside* the yurt (through the open lattice). On Saturday, Kyle attached cardboard blinders to the sides of both motion sensors, and this helped quite a bit.

We also found that a number of people couldn’t resist hitting the emergency stop buttons.

Future improvements

We could make the software much fancier for a future deployment. At Toorcamp, we simply operated the arduino microcontroller over PC USB, and interacted with it using keyboard commands over the Arduino IDE serial interface. What would be awesome would be to develop a graphical interface with continuous monitoring of the safety components and red/yellow/green display of their status.

Budget status

We are accepting donations through the end of August to cover budget overruns, which mostly occurred due to the cooling system. The array of 24 diodes we used came from a projector which was not designed to run the lasers at full power for any sustained period of time, so it was very difficult to extract the heat from the tiny module fast enough. The cooling system had to be rebuilt several times, with substantial enhancements and new parts each time.

To read more about this and to donate, please go here:


– h1kari and company from toorcamp for motivating the project and offering the grant.
– Owen Trueblood, Pierce Nichols, Phil Rutschman and Myles Conley for their work on the laser drivers.
– Ratha Grimes for majority of the electronics and software.
– Nathan Pegram for his work on the coolant system.
– Kyle Drosdick and Brian Campbell for setup and operations on site.
– DKP for software and making stuff happen, despite barely even going to toorcamp.
– Sirus for modding the OSPid so it works great with the TECs.
– Brett Beauregard for providing the OSPid and software and support.
– All of the folks offering support in various forms. Thank you!
– The fine members of hackerbot, who continue to do amazing shit.