Make: Online: Computers Archives

Archive: Computers

July 3, 2009

The USB... cigar?

This thing is wrong on so many levels, it almost reaches back around to right. Almost.

Some mobile carriers have started selling subsidized netbooks with integrated 3G radios. If you've already got a netbook and enjoy the form factor, but would rather not have to plug in a dongle, here's a quick run-through for integrating a Novatel EU850D 3G radio into a Dell Mini 9 that should give you an idea of what such a project entails.

How-to: 3G to Dell Mini 9. Not so easy way.. [via jkkmobile]

July 1, 2009

The first ethernet cable

Lisa Katayama writes on Boing Boing Gadgets:

Behind an ordinary door in a nondescript room hosting several printers and copiers at PARC is the world's first Ethernet cable. In 1973, Bob Metcalfe sent an internal memo to his colleagues at Xerox proposing a local system of interacting workstations, files, and printers. The devices would all be linked by one coaxial cable, he said, and would run within a local area network. He called the system an Ether Network, or Ethernet. By 1976, there were over 100 devices linked into Metcalfe's local network, and it was even used to test out the world's first laser printer, which was being developed concurrently in another research facility within Xerox. Metcalfe and his assistant David Boggs published their findings in the Association for Computing Machinery later that year. The rest is history.

Photo and original diagram of the world's first ethernet cable

June 29, 2009

SPARK Project #1, Post #5

Shawn Schaffert's ratcheting scheduler

Real Time Operating Systems?

Even though this project is about a smart home dashboard that doesn't necessarily have any time-critical tasks, it very easily could. What if a cloud covered the solar panels, and I wanted to dim the lights in response. I don't want my software to wait for all the temperature sensors to finish updated before changing the lighting. To avoid this potential problem, I want a "Real Time Operating System" for my project.

Systems using embedded controllers are often characterized by the need to exhibit real-time computing behavior. It's important to understand what this means and how it affects the choice of software to use in a project. No one would argue that computers have been getting faster and faster over the years. Hard drive, memory, video card, and motherboard speeds and clock rates have been steadily increasing with each new generation of hardware. This has meant that the user can run complex applications without having to wait unreasonable amounts of time, and that simple applications perform their functions in vanishingly small time increments. For most desktop applications, small delays in program execution are unnoticeable and insignificant. But what if part of your application monitors the emergency-stop button for your home-built CNC milling machine? You need the emergency-stop button to shut the machine down within a guaranteed amount of time. Not having this determinism could create a very dangerous situation if, say, a background task like playing music or saving a file have momentarily taken over the computer bandwidth. You press and release the emergency-stop and watch in horror as your mill bit keeps going right through your part.

It doesn't take a powerful or fast CPU to give a timely response to a single bit change in a peripheral I/O register. Anyone who has programmed a port interrupt in a simple 8-bit microcontroller can figure out how long it will take for the 8-bit processor to capture the I/O interrupt and call the code to respond to the event. With PC operating systems like OSX, Windows, and Linux, there is some ability to implement "real-time" threads, but this capability is often implemented by overriding the operating system's normal behavior by using an operating system add-on to achieve this capability. These operating systems were designed to be effective general purpose tools for running a wide variety of applications and interacting with numerous third-party hardware devices, but they were not designed to have real-time, deterministic behavior.

A true real-time operating system (RTOS) is designed with features such that a program can be split into tasks which run on a fixed schedule, and asynchronous events, such as the CNC mill emergency-stop button press, will have a guaranteed maximum latency before they execute. You can write a program to toggle one I/O pin at 5 kHz and another at 1 kHz with minimal jitter, or program the emergency stop button response to shut off your CNC mill motors within a guaranteed 1 millisecond.

Check out a list of real time operating systems and find out about Windows Embedded CE 6.0 R2 here.

This SPARK Your Imagination Make: Windows Embedded project series is sponsored by Microsoft Corporation.

How-To: Dual USB/serial cable for Nikon Coolpix cameras

I recently got it in my head that I wanted to take some time-lapse photos showing the oxidation of various bright-polished metals over the course of a week or so. Investigating the possibility of setting up an intervalometer for my elderly Coolpix 4300 quickly became frustrating, however, as I realized that I was facing a nightmare of proprietary connectors, unpublished protocols, and exotic cables. Nikon manufactured a time-lapse controller compatible with my camera (the MC-EU1), but all the reviews I've seen are unfavorable, and I can't find one for sale for less than $85.

To make matters worse, it turns out the proprietary 8-pin connector used on the 4300 and other older Coolpix cameras is dual-function: Four of the pins provide for normal USB connectivity, while the other four provide the serial interface used, for instance, by the MC-EU1 to remotely control the camera. My camera was supplied with a cable to access the USB half of the connector, but of course getting to the serial pins requires the purchase of a completely different cable (the SC-EW3), which can't be had for less than $30 plus shipping.

Fortunately, I then stumbled across this excellent tutorial by David Holmes about how to convert the connector on the bundled USB cable into a dual-use USB/serial cable that lets you swap out the proprietary end with two different harnesses that access the USB or the serial pins as needed. Thanks, David!

P.S. I've found a promising piece of freeware called Snappixx that claims to control the Coolpix cameras through the serial interface. I can't vouch for it yet, however, other than to report that it downloads, installs, and starts up without any apparent hitches.

June 26, 2009

Hack a Day's Bus Pirate

The folks over at Hack a Day have gone into the electronic components biz. Teaming up with Seeed Studio, they're producing the Bus Pirate. The Bus Pirate is a universal serial bus tool. Use it for understanding how components work before you build a full prototype. Their parts posts page shows many example uses. Here's more about the board:

The Bus Pirate is a universal bus interface that talks to most chips from a PC serial terminal, eliminating a ton of early prototyping effort when working with new or unknown chips. Many serial protocols are supported at 0.6-5.5volts, more can be added.

* 1-Wire
* I2C
* SPI
* JTAG
* Asynchronous serial
* MIDI
* PC keyboard
* 2- and 3-wire libraries with bitwise pin control

We added other stuff we need, like,

* 0-6volt measurement probe
* 1hz-40MHz frequency measurement
* 1kHz - 4MHz pulse-width modulator, frequency generator
* On-board multi-voltage pull-up resistors
* On-board 3.3volt and 5volt power supplies with software reset
* Macros for common operations
* Bus traffic sniffer (SPI)
* A bootloader for easy firmware updates

Since this has been such a useful tool for us, we cleaned up the code, documented the design, and released it here with specs, schematic, and source code.

The Bus is available for pre-orders and sells for $27.15.

Bus Pirate preorders open
How-to: The Bus Pirate V2 with USB
The Bus Pirate universal serial interface

June 25, 2009

Shapeways adds free 3D parts database

Shapeways now offers free, Creative Commons licensed mechanical parts models that we can use in our projects. I'm sure they'd love it if we used these CAD models to build the contraptions of our dreams on the computer and then printed them through Shapeways, but even if we don't, the virtual models are ours to keep.

I haven't built any 3D printed mechanical models yet, but I've been impressed by the results of other designers. Check out this functioning roll-back racer. This is science fiction, right?! Unlike the excellent Thingiverse, this is not a community-driven database, but Shapeways says they plan to allow user-contributions in the future.

The files are in the STL format, which most 3D modeling packages I've dealt with can import.

Shapeways 3D parts database

June 24, 2009

Adam and Jamie's giant coding cryptex

Those inspired crazies at Mythbusters, Adam Savage and Jamie Hyneman, built a giant, working coding cryptex. The device was built for a demo at the RSA Conference, held at the Mascone Center in SF, in April. Now the pair is auctioning it off on eBay. Proceeds from the sale will go to the EFF.

You can watch a video of the demonstration at the conference here.
The auction page is here (auction ends Jul-03-09 10:14:40 PDT).

June 18, 2009

Interactive ping-pong table / virtual aquarium

Ah, the gay (19)90s: before Y2K, 9/11, Gitmo, CDOs, and all kinds of other depressing modern acronyms. Venture capital fell from the sky like manna, and everyone was getting rich on the Internet, even though nobody knew exactly how. Enter, into that milieu, the following brilliant idea, courtesy of the wunderkinder at MIT's then-ascendant Media Lab: Ping-pong tables ought to contain schools of virtual fish that react to the impact of the ball. The rave toy to end all rave toys!

Pre-coffee sarcasm aside, this really is pretty cool. PingPongPlus is the work of Craig Wisneski, Julian Orbanes, Ben Chun and Professor Hiroshi Ishii. The "fish" mode is only one of several possible interactions, and they all include sound effects. Check out the vid:

June 17, 2009

SPARK Project #1, Post #4

One of the most important functions of an embedded system is the ability to connect to a variety of external signals. For my smart home energy efficiency dashboard, the signals come from a variety of sensors and use a range of different protocols. Ideally, I'd like to handle these signals in software by creating a custom driver for each signal, or better yet, by configuring an existing driver to connect each sensor. In some cases, the sensors may require additional signal conditioning or interface circuitry to before being connected to the embedded processor board. Sometimes it's appropriate to use a small microcontroller to provide the interface or signal conditioning. This provides additional flexibility, but also requires programming a second processor. Where possible, I like to avoid programming and debugging multiple computer systems. With that in mind, I'm taking a close look at computing system selection.

Microsoft has teamed-up with six hardware partners provide a range of computing system options with a variety of different feature options. Special pricing is available for non-commercial use as part of the SPARK promotion. These prices vary from system to system depending on capability and included accessories, and each computing system is ready-to-run out of the box. Ready-to-run means different things to depending on your level of exposure to embedded systems. In most cases, these computers are ready for you to load an operating system onto the device via a bootloader. Many of the configurations of the boards are managed through standard BIOS at power-on. With the exception of the VIA Artigo which doesn't come with RAM or disk storage installed, the computers include the basic components load an operating system and run applications.

Download my SPARK hardware comparison chart and read more about the available hardware features on the SPARK Project blog.

Learn to program music in Pure Data

Pure Data, or Pd as it's known, is an open source, visually oriented programming environment similar to the popular MAX/MSP software. One of the only issues with going with free Pd is the scant amount of formal documentation available to newcomers. Thankfully, Johannes Kreidler's loadbang Programming Electronic Music in Pd provides a bookfull of tutorials and lessons free via the web. Check out the html version here.

June 12, 2009

Building a dynamically generated city

Shamus wrote some impressive procedural city software in OpenGL and posted this simple summary of how the process works -

The project is bound to Windows right now. Several people made great suggestions yesterday for wxWidgets, Qt or SDL. I don't have time to examine those now (the interface is already done and I'm anxious to move forward) but I am making a note to make sure my next project is written on something portable.
I'm using OpenGL for rendering. The API seems more quaint every year, but it still gets the job done without getting in the way.
The look I'm going for is a helicopter-level view of a city, not a street-level view.
The city is going to be pretty basic. 30 hours is not much time, and I'm aiming for simple-yet-effective as opposed to profound and feature-rich. While a lot can be done with a procedural city, I'm not going to take this idea very far to begin with. I just want something that's fun to view for a couple of minutes.

Not much in the way of specifics, but much more info can be found on the Twenty Sided blog - p1, p2, & p3 [via Create Digital Motion]

June 11, 2009

SPARK Project #1, Post #3

I came across this very elegant residential energy efficiency dashboard from Agilewaves as I was thinking about user interfaces for my smart home project. I like the clean, intuitive design and the logical layout. Skilled interface designers were probably involved with creating this interface. I won't pretend to be a skilled interface designer, and I do want to create a simple user interface that communicates historic resource usage and current usage measurements. There are a lot of tools available to create complex user interfaces with back-end stub code to simplify programming. Much of my programming experience involves embedded systems, and I prefer hacking systems that hide inside larger electromechanical devices, with an embedded controller to handle measurement and control with specifically defined user interaction. Thus, AJAX and PERL are not the first tools I grab to create an interface. I do have pushbuttons, 4 bit to 32 bit microcontrollers, and LCD displays at the ready in my tool kit. With those tools in mind, I've set about creating a basic look and feel for my dashboard.

In my previous posts, I outlined some of the general requirements for a smart home network that aggregates energy generation and usage data for a net-zero building. I have looked at basic measurement and control needs of the building's users, and the sources of signals and the sensors needed to acquire those signals. I want to display this information to the users and occupants of the building. As a place to start, I've drawn some basic widgets that will be fed data for display.

Continue on to the SPARK Project blog to see more.

June 10, 2009

Multi-flash camera makes automatic line drawings

Here's an oldie-but-goodie from 2004: Kar-Han Tan, James Kobler, Rogerio S. Feris, Paul Dietz, and Ramesh Raskar, then of the Mitsubishi Electric Research Laboratory (MERL), produced a custom digital camera and software that derives line drawings of a scene, or an object, by analyzing the shadows in four otherwise-identical pictures that are illuminated from different quadrants. The MERL has a technical report from 2005 describing potential medical applications of the technology, and photo.net has a good general overview of the process. Raskar has since gone on to the MIT media lab (so you know he's doing something right), and his page there includes more up-to-date work on the technology.

Thanks to Jon Wolfe for bringing this to my attention.

Real-time 13" MacBook Pro teardown

Ifixit got ahold of a new MacBook Pro 13" and are posting the teardown as they take it apart and explore what's inside.

MacBook Pro 13" Unibody Teardown

Teaching mirrors new tricks

Andrew Hicks, a mathemagician at Philadelphia's Drexel University, has lately made headlines with one of those head-slappingly simple, brilliant, OMG-why-didn't-I-think-of-that sort of projects: He makes mirrors. Not the run-of-the-mill flat mirrors most of us use every day for identifying vampires, but totally unorthodox, heretical, downright blasphemous mirrors with convoluted surfaces that do tricks I didn't even know mirrors can do--like reflecting things the right way 'round! New Scientist has some nice photos, and PhysOrg the story.

June 9, 2009

Android/XP Frankenbook hybrid device

The Institute for Information Industry in Taiwan have cobbled together from existing parts a truly unique device. It's part netbook, part tablet. They started by gutting an HP Mini 1000 and replaced the Intel Atom chip with a Via processor running XP SP2. They then removed the standard display and replaced it with a tablet of the same size running Android. Pop the tablet out of its holder and you've got a fully functional Android tablet. Slide it back into the base with the keyboard and you're running XP.

via howtobemobile

June 8, 2009

ThinkSafe: A Magnetic Power Connector for Thinkpads

Got a ThinkPad and have a tendency to trip over the power cord all the time? Envious of all those silver MacBooks with their stark minimalism and futuristic MagSafe power cables? Well, you're in luck. This Instructable will show you how to assemble your very own ThinkSafe magnetic power connector.

My Thinkpad's power connection started getting flaky, so I made a magnetic connector that works just like Apple's MagSafe connectors. It's effective, cool-looking, and breaks away cleanly when kicked. I used common materials that I had around or could find at my local hardware store, so you should be able to duplicate my efforts.

June 5, 2009

SPARK Project #1, Post #2

In my previous post, I presented some background on the green building where the SPARK Project #1 is being installed, and I discussed the basic signals that need to be measured for the project. In order to create inputs into my smart home dashboard, I need to measure temperature and humidity, both indoors and out, photovoltaic array output, solar thermal usage, and grid-tied energy input. I described how temperature, humidity, and photovoltaic output were going to be measured.

The local utility has already installed devices that measure natural gas usage and grid-tied electricity consumption, but they don't provide the homeowner any way to read these measurements in real time. As with any dashboard, it's pretty important that the information displayed is as close to real time as possible. Imagine trying to optimize the efficiency of your car based on monthly reports. It can be done, but it's difficult to understand the impact of each change to the system. Electric and gas meters may be available with outputs suitable for monitoring, but I don't think most hobbyists have the option of retrofitting their homes. Fortunately, better and less intrusive options do exist.

Read further on the SPARK Project blog to see how the remaining signals will be measured.

More:
SPARK Project #1, Post #1
Sponsored projects series with Windows Embedded CE

This SPARK Your Imagination Make: Windows Embedded project series is sponsored by Microsoft Corporation.

Android on OMAP

Android seems to be popping up on everything these days. Netbooks, set-top boxes, embedded devices, washing machines, E-Ink displays, you name it. Of the many available solutions out there it seems that some folks are having great success with OMAP-based solutions such as Gumstix and the Beagle Board. The combination of low power and high performance delivers reasonably efficient Android-based solutions that fit well in tight spaces.

One thing that impressed me in the above videos is Android's ability to adapt to the display. Full-screen web browsing seems right at home on the Beagle Board connected to an external monitor.