Why hasn't Brandon been blogging recently?

May 11, 2011 | categories: rascal | View Comments

This blog has tended toward dormancy over the last year because I've been pouring all my energy into a new project, the Rascal. It's a small computer aimed at artists and scientists who want to add web interfaces to their projects. It similar to the Arduino, but much more powerful.

Recently, I've been alternating between working on the Rascal and various renewable energy engineering projects with Matt Dorson at Mystic River Engineering. In April, the first batch of Rascal beta units arrived from an assembler in China; I've sold 4 of them to various adventurous friends of mine for hardware testing. In the immediate future (May, June), I'm working on a project at MIT with Matt, but on the side, I'm selling more Rascals and gathering results from hardware testing. Depending on the results of the tests, I'll either commit to a larger batch of 100 Rascals, or run another small batch with improved hardware. If you're interested in the Rascal, you should follow the Rascal on Twitter here, or add your email address to the announcement list on the main page of the Rascal website. There's also a quick video interview of me explaining how the Rascal works. It was shot by Chris Connors at the 2011 mini-Maker Faire in Cambridge, MA, USA.

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Thoughts on the 2010 Open Hardware Summit

September 28, 2010 | categories: rascal, openhardware, embedded | View Comments

Last Thursday, I went to the Open Hardware Summit in Queens, NY. The Summit had a lot going for it-- people from all of the major open hardware players were there (Arduino, Adafruit, Sparkfun, Bug Labs, and Beagleboard, to name a few), and it took place at the New York Hall of Science, a cool science museum right next to Flushing Meadows with its enormous, awesome Unisphere.

For the past few months, I have been working solo on a device that I intend to be open hardware. In my circumstances as not just a "small business," but the smallest possible business, the crucial question is whether opening my hardware designs to the world will result in someone taking a design and replicating it more cheaply than I can, thereby stealing all my customers. Against that fear, I have the hope that opening my designs will result in people improving them in ways that I can't predict.

This issue came up repeatedly at the summit. Many of the speakers were actually building and selling open hardware. Very few came from VC-funded companies (Bug Labs is the notable exception). Most of them were engineers who had bootstrapped their way from a few small designs they made themselves. They are evidence that my fears are unfounded, particularly in my current state of obscurity.

The explanations varied. Limor Fried of Adafruit said something like, "People say they will copy you, but it's hard to actually do. . . . Being obscure is worse than being ubiquitous." (A video of her talk is now available.)

In a later talk, Chris Anderson, who runs DIY Drones, mentioned the power of the community. They design small, autonomous aircraft and release all the plans on the internet. Their customers buy the electronics from DIY Drones and then tweak them. Anderson isn't worried about closed competitors: "We think the customers will go with the community." He also pointed out that the community of drone zealots was innovating faster than most private companies; even if you were to copy the hardware today, you'd be obsolete in short order.

After one of the panels, I talked to Nathan Seidle of Sparkfun for a few minutes. Sparkfun is the internet version of what Radio Shack was in the 70's, when they sold lots of electronic components. They have over 80 employees and around $10M in annual revenue. I asked Nathan why Sparkfun, if run by an evil version of him, wouldn't just collect open hardware designs and start replicating them. His answer was that breaking the trust of the community like that would devastate his sales.

Later in the day, I talked with Chris Gammell of the Amp Hour for a few minutes. He said that he was worried about what was going to happen when larger distributors enter the open hardware market. This is an interesting point viewed in the light of Nathan Seidle's and Chris Anderson's comments about the trust of the community. When the open hardware community is a small subgroup of a 10-100 thousand people forming a somewhat cohesive culture, losing the support of the community might be catastrophic. But if the electronic hobbyist world grows so that most of Sparkfun's customers don't even know that the hardware they're buying is open, it might be worth it for a giant like Digikey to risk alienating the hardcore open hardware folks. The situation might be like the libertarian anti-Obamacare editorial published by the CEO of Whole Foods in the Wall Street Journal last year-- hardcore liberals started boycotting Whole Foods, but the majority of their customers didn't care, because have you tried their almond cookies?

For me, as a new entrant to the market, I have no worries about a large corporation stealing my ideas-- risking the $100,000 it would take to beat me on volume on the hope that this solitary engineer has come up with a winning product would be colossal folly. I do think that the Rascal will be a great product, but it's definitely not there yet, and it will take a community of users to get it there.

Footnote: mbed.org

One other interesting note-- during lunch, I met Simon Ford and Dan Ros of mbed.org, a small group within ARM that is making development tools for ARM processors. The Mbed is not fully open hardware, though they do distribute schematics of the system. Simon said it was because he wanted to be sure they were built right.

The Mbed is an interesting board. It actually has two microcontrollers on it. The main processor, on top, is an LPC1768 running at 96 MHz. There is a second processor running at 12 MHz on the underside of the board that acts as the programmer for the first processor. You compile your code on their website and then transmit your programs to this supervisory processor via USB. It puts the code on the second processor via JTAG. The advantage of this is that the main processor behaves exactly as it will in a final design. You can design a device using the mbed, and when you're done, you can buy the same LPC1768 processor and replicate what you've got, minus the second processor, which is no longer necessary. It's an elegant architecture.

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Dynamic image listing in PHP

August 20, 2010 | categories: code, php | View Comments

I've been working pretty hard on a top secret project for the last couple of months, so the blog posts have been a little scarce. More details about the top secret project (TSP) shortly, but in the meantime, here's a little PHP script I wrote this morning.

Having switched from Wordpress to Jekyll (a blog compiler, if you will), I needed a way to quickly browse a directory of images on a webserver and copy links to the images for insertion into blog posts. The PHP script below, if saved as index.php into a directory of images you want to browse, will create a page showing 200-pixel wide versions of all the images in rows of 5. You can tweak the image size and row length by changing the 200 and 5 in the script.

It's not kind on bandwidth, as it makes you download all your images, but it's simple. Save the code below as index.php with your images, and then browse to that file in your image directory (something like http://yoursite.com/img/index.php). Assuming your webserver has the PHP engine running, you'll see rows of images. You can then grab links by right-clicking and paste them wherever you like.

The code

<!DOCTYPE html>
        echo "<table>\n";
        echo "\t\t<tr>\n";
        $i = 0;
        if ($handle = opendir(".")) {
            while (false !== ($file = readdir($handle))) {
                if (strstr($file, "png")||
                    strstr($file, "jpg")||
                    strstr($file, "bmp")||
                    strstr($file, "gif")) {
                    echo "\t\t\t<td><a href='".$file.
"'><img src='".$file."' width='200px' /></a></td>\n";
                    if ($i%5 == 0) {
                        echo "\t\t</tr>\n\t\t<tr>\n";
        echo "\t\t</tr>\n";
        echo "\t</table>\n";
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Liquid metal batteries

April 29, 2010 | categories: energy, engineering | View Comments

I've recently started a contract at work for Professor Donald Sadoway's lab at MIT working on liquid metal batteries. I can't describe the details of the project I'm working on, but the research going on in the lab is quite interesting. The idea is to solve the problem of energy storage that accompanies all of our promising renewable energy solutions, like wind and solar. When the wind stops blowing or a cloud obscures the sun, the electrical grid still needs to supply energy to the world. If you only have a small amount of renewable power attached to your grid, you can just ignore the problem, but around 20% penetration, you get into trouble. Our best solution right now is either firing up natural gas turbines to cover the peak loads or pumping water up a hill when we have extra capacity so it can run down through a generator when we need it back.

What we really need are massive, cheap, efficient batteries. The idea in the Sadoway lab is to make something like an aluminum refinery, but instead of just sinking huge amounts of electricity to extract aluminum, you set up a reversible reaction so you could get the electricity back later.

Go take a look at this awesome, enormous picture of one of these furnaces in an aluminum refinery so you know what I'm talking about. Look at the size of the guy in the picture, and then look at how many furnace chambers there are in the row. That's an industrial scale operation.

To make aluminum, you dig bauxite out of the ground and use heat and sodium hydroxide to extract the part that's aluminum. What you get out, unfortunately, is oxidized aluminum, known as alumina. This is because aluminum, in its elemental form, reacts with oxygen, and when it sits in the earth for eternity, there's plenty of air seeping around, so all of the aluminum bonds with oxygen.

Fortunately, we have electrochemistry on our side. The large smelting furnaces in the picture you looked at a moment ago are long steel troughs that are lined with carbon and filled with aluminum oxide. These form the two electrodes in a chemical reaction. When electricity is run through the carbon into the aluminum oxide, the oxygen releases from the aluminum and bonds to the carbon, creating carbon dioxide, which is then vented to the atmosphere to help keep the planet warm. During the reaction, the aluminum oxide in the center heats up and liquefies, while the outer crust remains solid, sort of like the liquid-filled gum of the 70's, Chewels. (You may also recall Freshen-up, "the gum that goes squirt.")

To turn this process into a battery, we need an electrode that doesn't turn into a gas, and we'd like both electrodes to be cheap and lightweight, relative to the amount of energy they can store. Sadoway's lab started with one magnesium electrode and one antimony electrode, with a salt electrolyte in between. (They have since moved on to better combinations that I'm not at liberty to describe.) If you heat the core of the battery up to 700 C, everything becomes liquid, and the resistance drops substantially. Most remarkably, the three materials separate by density โ€” electrode, electrolyte, electrode โ€” all in a stack.

What's so great about a liquid metal battery? They have several advantages, notably extremely low internal resistance and huge current capability. Aluminum refineries run at currents above 100,000 amps. For comparison, most household circuitbreakers blow at 15 amps. The low resistance of liquid metals means that the battery is likely to charge and discharge very efficiently.

At first, the fact that the battery needs to run at high temperature seems like a major disadvantage โ€” if you have to dump a lot of energy into heating, that makes the battery less efficient. This is true, but what's not obvious is what happens to a furnace's thermal behavior as it grows in size. In general, hot objects cool off in proportion to their surface area, which grows proportional to the square of the size of an object, roughly speaking. The capacity of a battery, however, grows with its volume, which is proportional to the cube of its size. This means that as the battery becomes huge, the amount of heat loss per unit of capacity decreases, i.e. the volume overwhelms the surface area. It's this same property that allowed icehouses in pre-industrial times to store ice well into the summer. There's some hope that at the right scale, with the right insulation, the small inefficiency in charging and discharging the battery will suffice to keep the core in the molten state.

So that's what I'm working on recently. (I'm still working on a Linux board on the side, but it's kind of on the back burner for the next month or so.)

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Designing embedded systems with web frameworks

April 12, 2010 | categories: rascalmicro, python, embedded electronics, django, engineering, geekery, linux | View Comments

I have a prediction.

We're about to see a shift in embedded systems development. Around 2008 or 2009, embedded microprocessors like the one in your cellphone, reached a threshold where they can perform as decent webservers without special tuning. Even with a slow database query or some inefficient templates, they've got the speed to handle real web serving. This means that suddenly the most efficient development pattern for embedded systems is not the proprietary hardware and software tools that have dominated the industry for the last 30 years, but the open source web development tools that have arisen in the last decade.

The transition will be painfully slow, and of course there are some niches where specialized hardware and real-time control will preclude the use of generic web tools-- motion control springs to mind. But I think that the combination of cheap hardware and modern web frameworks will crush the industrial controller market, like digital cameras did to film cameras.

First, some background on tiny computers

There are millions of tiny computers used for monitoring and control systems around the world. Let's break them into two categories: small (microcontrollers like the Arduino or a PIC development board, which runs $10-500) and large (embedded controllers like National Instruments hardware, which cost $500-5000).

To use the small ones, you write code from scratch, perhaps with some pre-written libraries to talk to certain peripherals and a bootloader to run your code on power-up. The vast majority cannot be connected to the internet without substantial effort, and when connected to the internet, they aren't powerful enough to work like most servers on the internet. For example, a webserver built on a small microcontroller would be overwhelmed by the background noise on the internet, i.e. traffic from bots and viruses. This kind of system is perfect if you want to log temperature in your basement, or turn on a light whenever the garage door is open. They're no good for running an inventory management system in a warehouse with 20 workers.

Below: an Arduino

The large ones come with an operating system, like Windows CE, Linux, or VxWorks. Most of the devices are reworked versions of hardware from the pre-internet days that have had Ethernet ports added to them. They can handle real internet traffic, but they usually use proprietary software to do it. They're shaped like a long, skinny shoebox.

Below: a larger controller

A programmable logic controller

The change is that something equivalent to the iPhone, which uses a 600 MHz ARM processor, can store years of data and serve it up to anyone with a web browser in seconds with hardware cost of a few hundred dollars. Industrial controllers lose on cost of both hardware and programming time, and performance. The hardware has to be expensive to support the R&D costs, which are borne entirely by each manufacturer. There's just no way that even a large industrial control company, which might have a dozen dedicated programmers at best, can compete with the thousands of developers working on open source web software worldwide.

How web software development has changed

In the 90's, software development for the internet meant either writing server software or designing static web pages. Starting around 2000 (give or take a few years), websites started incorporating dynamic data, which was stored in databases. Around 2005, a new kind of web software gained popularity-- the web framework-- with the release of Ruby on Rails.

With old-style web development, a web programmer would write code that inserted data into a database, more code that updated the database with new data, and more code that retrieved and sorted the data for presentation in a web page. With a web framework, the programmer writes out a template for how the data should be presented on a webpage, and the framework figures out what to request from the database. Web frameworks can't scale to the level of a big website like Amazon, but for low traffic systems, they work fine and reduce the programming time needed dramatically.

Most of the time, what people want to do with microcontrollers is log some data from sensors and maybe trigger some actuators in response. After they log the data, people want to analyze the data, make graphs with it, and then do it again, maybe with a different sensor. This matches well with the typical database-backed website. The only substantial additions are code to interact with hardware-- read sensors and trigger actuators. I think this is the least developed part of the systems I expect we'll see in the next few years.

Proof of concept

It's definitely possible that I'm just some blowhard on the internet. I mean, I'm at least some blowhard on the internet, but I might still be right in predicting this change. To that end, I've done some testing to see whether I'm going in the right direction.

Using an off-the-shelf microcontroller kit that cost $339 plus shipping, I installed a Python web framework called Django and wrote code to make it act like a thermostat to replace the one in our house. It took about 2.5 weekends to write the code, which is much faster than I could write a similar application for something like an Arduino with an Ethernet carrier board, and this was my first try. I had played around with Django a few times previously, but this was my largest effort by far.

Below: the proof of concept

The web thermostat in place

The hardware interface is just a cron job that runs once per minute. It queries a temperature sensor on the PCB using a short C program called by a Python script, which also logs the data to a SQLite database. Retrieval of a webpage that queries the database for the last 300 datapoints (5 hours worth) and generates a chart of the data using Javascript takes around 1.5 seconds. That's with a processor running at 250 MHz (relatively slow) and the database stored on an SD card. Most of the time is spent converting Python datetimes to Javascript timestamps.

I could have written a similar application even faster using a GUI tool like LabView, but that requires specialized hardware that cost 3-10 times more-- either a dedicated PC with a USB device for sensors, or a industrial controller with a sensor module. With Django, I got an administrative interface, allowing different users and groups different levels of access, for free. If I want a central repository of users with LabView, I'm looking at another $800 for the "Datalogging and Supervisory Control Module." If I want to talk to a SQL database, I'll need the "Database Connectivity Toolkit" for another $1000. This is on top of the $1500 I would have paid for LabView already, plus the hardware.

Embedded control systems running web services are still an immature technology at best, but I think they'll grow up quickly in the next few years.

Why are you writing this?

I've been thinking about this change for a year or two now. I'm working on developing something like the Arduino, but a little heavier duty, so it can run a web framework, but with the hardware drivers pre-integrated. Send me an email at brandon at pingswept.org or post a comment if you want to know when it exists for real.

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