Looks like the Lightweight USB Framework for AVRs (LUFA) has just been ported for ARM microcontrollers. NXP recently released a package for their LPC Cortex M3 family of ARM controllers. You won’t find a reference to LUFA on their nxpUSBlib description page (which we think is kind of sad), but if you grab a copy of the beta code the Version.h header file shows that it is indeed a port of the project. This is further backed up by the LUFA creator, [Dean Camera], who consulted with the NXP team doing the work.

The package provides an open-source USB stack that you can use in your projects as a USB host or USB device. We’re advocates of open source packages like this one as it makes it much easier for hobbyists to get help using the tools, and it allows the community to give back through bug fixes and feature additions.

We’ve highlighted a few LUFA projects, like this keyboard remapper and this AVR programmer. We’re looking to seeing the first set of NXP LUFA projects roll through!

[Thanks Johnny]

We asked for responses to our last Development Board post, and you all followed through. We got comments, forum posts, and emails filled with your opinions. Like last time, there is no way we could cover every board, so here are a few more that seemed to be popular crowd choices. Feel free to keep sending us your favorite boards, we may end up featuring them at a later date!

The Popular:

Parallax Propeller: We heard the loudest cries from the Parallax fans out there. The Propeller is a unique chip, in that it contains 8 cores called cogs which each take turns executing separate code. This design allows for disregarding of interrupt style programming in favor of assigning each core a specific task. There are a number of boards available, including Gadget Gangster’s platform as well as boards from Parallax. Thinking in terms of 8 cores rather than one may present a learning curve to some embedded programmers, though there are a number of code examples to pull from online to get beginners on their feet.

Atmel’s AT90USB and AT32U4 based boards: Atmel’s AT90USB and ATmega32U4 chips are common on low part count boards like the Teensy/Teensy++ because of their built-in hardware USB support, which means no FTDI or equivalent chip required. These development boards tend to be low-cost, easy to implement on a breadboard, and in cases such as the Teensy, are Arduino IDE compatible. The chips these boards are based on are also an excellent place for those trying their hand out at microcontroller circuit design for the first time because of their simplicity and low hardware requirements.

Microchip’s PIC line: Somehow, we managed to leave the entire Microchip crowd in the cold last time. A popular set of microcontrollers with a similar market segment to Atmel’s chips, these chips vary from the low-end and low-cost 8-bit series to the higher end 16 and 32-bit models. We received a good number of development board recommendations, all ranging in price, features, and ease of use. We’ll rely on comments and forum posts to help convince you what specific model to try.

[edit: Added the PicKit3 as per popular request]

The Powerful:

mbed: Possibly one of the most popular hobby development boards for ARM’s Cortex-M3 chip, the mbed features a similar footprint to the Teensy, but with a huge jump forward in power. The mbed includes hardware for a number of peripherals, including support for ethernet with the addition of an RJ-45 port. The major difference between the mbed and other similar boards is the entirely web-based IDE. We have previously reviewed the mbed, so for more details be sure to check it out.

Renesas’ RX62N RDK: Whenever a company gives away development boards for free, the community often jumps on the offer. Rather than the normal free barebones boards though, the RDK has a good number of on board peripherals, including an Ethernet port as well as a 3 axis accelerometer. Unfortunately you can’t get one for free anymore (at least not this contest), but from all we have heard from our readers, it may be worth investing in anyway.

The Maple: The Maple from LeafLabs is an excellent example of the effect open hardware tools such as the Arduino have had on the hobbyist environment. Featuring an ARM Cortex-M3, the Maple has plenty of processing power and also can brag that it has the same header layout as the Arduino. This means that almost all commercially available Arduino shields will work on the Maple, a major selling point for anyone who has invested into a well stocked Arduino setup but needs an injection of performance.

Bonus Points:

OpenWRT based routers: Often, projects need to be networked either by wire or wirelessly to operate as desired. Rather than buying a high-end development board with ethernet or Wi-Fi built-in, many readers suggested buying (or salvaging) any one of a number of low-cost wireless routers, and installing a custom linux based firmware on them. These boards often tend to have UARTs or USB ports originally meant for debugging available for expansion with sensors or other low-end microcontrollers. A hack in the true sense of the word, we applaud this sort of creativity. Some popular firmwares to check out would include DD-WRT, OpenWRT, and the Tomato firmware. Be sure to make sure support exists for your device before you go buying anything though.

FPGA boards: When we set out to cover development boards, we had microcontrollers in mind. However when it comes to signal processing, custom high-speed logic, or flexibility, FPGAs are an excellent choice. The two major players for hobbyists these days are Xilinx with their Spartan line, and Altera with their Cyclone line. Both companies offer their IDE for free, and it comes down to personal preference when choosing which way to go. Both companies also support SoC designs to implement virtual microcontrollers on the FPGA, which adds an additional layer of flexibility for any hobbyist or engineer. Chances are, most hobbyists will not need the performance of cutting edge FPGAs (or CPLDs), so keep an eye out for older development boards on sale, or development boards made by third parties.

Build your own: Although it may appear as a sort of “Get off my lawn” answer to our question, there is a lot to be said about building a development board from scratch. These days, many 8-bit or 32-bit microcontrollers require few if any external components to run in a basic mode, and can be combined with a JTAG or FTDI cable for programming and communication. There are countless tutorials on using perf-board or etching a board to make a custom circuit, and the experience is invaluable for breaking away from high cost development boards in simple projects.

Ah, the heady aroma of damp engineers! It’s raining in Silicon Valley, where the 2010 Embedded Systems Conference is getting off the ground at San Jose’s McEnery Convention Center.

ESC is primarily an industry event. In the past there’s been some lighter fare such as Parallax, Inc. representing the hobbyist market and giant robot giraffes walking the expo. With the economy now turned sour, the show floor lately is just a bit smaller and the focus more businesslike. Still, nestled between components intended to sell by the millions and oscilloscopes costing more than some cars, one can still find a few nifty technology products well within the budget of most Hack a Day readers, along with a few good classic hacks and tech demos…

(Is that a promise or a threat?)

First order of business was to follow up on a couple of products we’ve covered in the recent past…

We reviewed NXP’s mbed prototyping platform in November of last year. While there’s no stunning new revision, the good news is that the mbed community is going strong and economies of scale have made it possible to trim the starter kit price from $99 back down to the original early adopter cost of $59.

Additionally, they’ve thrown together a project in just a few days to demonstrate the prototyping ease of the mbed platform. Reading like a checklist of Hack a Day clichés, the demo brings together Twitter, the Logo programming language, live web streaming, servos and an Etch-a-Sketch. You can read more on the mbed blog, or watch the live stream and participate during ESC show hours.

We also liked this little breakout board which adds the most essential interfaces to mbed: MicroSD, Ethernet and USB host & client. This was something quickly made for an mbed workshop, and while there are no plans to officially productize it, we’re told the unpopulated board might be available through SparkFun’s BatchPCB service in the future.

Many readers were put off by the web-centric development approach used by mbed, as well as the lack of a debugger. Another NXP entry-level evaluation product called the LPCXpresso provides an affordable ARM development kit from a more traditional angle.

The $30 LPCXpresso boards are available in Cortex-M0 or -M3 varieties and include an integrated JTAG debugger. The downloadable Windows development environment is based around the Eclipse IDE and GNU toolchain. With headers installed the LPCXpresso is breadboard-friendly and in fact shares the same pinout as mbed, so there’s an existing ecosystem of hardware to work from.

STMicroelectronics’ STM8S-Discovery made a huge impact when we mentioned this $7 kit in November, clearing out distributors in a matter of days. At ESC, ST was showing their new ultra-low-power 8- and 32-bit MCUs with demos powered by a cactus (a variation on the classic lemon battery), a cup of warm water sitting atop a Peltier junction, and a modest induction charger. (What, no wind power?)

A new version on the STM8S-Discovery based on the new lower-power chip should be available within a couple of months, and is expected to be similarly affordable.

(Left: the original STM8S kit that created the ruckus. Right: the forthcoming STM8L kit.)

At the Texas Instruments booth, the BeagleBoard XM was being demonstrated, which improves upon its predecessor in nearly every regard.

We’re told BeagleBoard XM stands for “extra MIPS,” “extra memory,” (and “extra money,” they joked). The XM does not replace the original BeagleBoard, but will be sold alongside it at a premium price of $179 when it ships in June. The XM includes a faster processor (1 GHz), more RAM (512 MB, and a 1GB model may be forthcoming), Ethernet, more USB ports and improved power protection. The NAND flash is gone, replaced by a MicroSD slot on the underside. The new board is slightly larger but retains the same mounting holes, so it may fit as an upgrade into some existing BeagleBoard projects.

Microchip’s iPod/iPhone accessory development boards that we mentioned last month were on display. Unfortunately it appears one must be signed on with Apple’s “Made for iPod” developer program before these kits can even be ordered from Microchip, which really puts a damper on the fun for anyone who might just want to tinker.

Drifting further from product specifics and more into hacks and eye candy…

Product teardowns have become a staple of tech culture. “Zero-day” and live blog teardowns of new products are particularly exciting. ESC’s gone one better, making a show of ripping into a product (if a rather esoteric one) months before its official release: a high-end Zircon AC wire detector built around a Microchip dsPIC and a bevy of e-field sensors. It’s like engineer pr0n!

National Instruments certainly had one of the most entertaining booths at the event. Rather than passively showing dry PowerPoint summaries and monitors running LabVIEW (their graphical programming environment for engineers and scientists), they instead presented physical demos and projects making use of the software. Some serious, others not-so-serious. Hacks!

Remember Waterloo Labs’ iPhone-controlled car hack? There it is! Rather, there it is minus the actual car, but with all the essential parts nicely laid out where we can observe the rig in action. At the other end of the booth, one can challenge “RockBot” to a round of Frets on Fire, not unlike prior hacks we’ve seen.

Hack a Day readers might be familiar with Digi International for their XBee wireless modules, such as used in Adafruit’s Tweet-a-Watt power monitor. Easily distracted by shiny things, we were initially smitten with this addressable LED matrix wrapped around their booth; not a product, just something to catch peoples’ interest:

As it turns out, there’s an added bonus hack behind the hack. Most of Digi’s booth displays could be controlled and monitored using their own custom web apps, so it was a simple matter of walking around with an iPod touch to run the show:

At the ARM pavilion, this “Speedcuber” was solving Rubik’s cubes in under half a minute. The camera and puzzle-solving logic comes from a Motorola Droid. Commands are issued over Bluetooth to a pair of LEGO Mindstorms NXT controllers to drive the motors that manipulate the cube.

Macraigor Systems produces a line of JTAG debuggers…but to be honest, we (and pretty much everyone else passing the booth) nearly missed that fact, as we were all so distracted by their demo application involving one spectacular and elegant Intel hexapod robot:

We similarly fanboyed over Cryptography Research’s German Enigma cipher machine, as it was our first time seeing one not under lock and key in a glass museum case:

ESC Silicon Valley runs through Thursday, April 29th, and last we checked one could still register for a free exhibits-only pass on the ESC web site.

mbed is a next-generation 32-bit microcontroller platform. It’s a prototyping and teaching tool somewhat along the lines of Arduino. On steroids. With claws and fangs. Other contenders in this class include the MAKE Controller, STM32 Primer and Primer 2, Freescale Tower, and Microchip’s PIC32 Starter Kit. The mbed hardware has a number of advantages (and a few disadvantages) compared to these other platforms, but what really sets it apart is the development environment: the entire system — editor, compiler, libraries and reference materials — are completely web-based. There is no software to install or maintain on the host system.

The Hardware

The mbed board is sensibly priced at $60; about middle of the road among its peers. mbed’s size (or lack thereof) is among its greatest assets, measuring only about 1″ by 2″ (26 x 52mm) in a stout 40-pin DIP package that just barely manages to fit in a breadboard…a major win.

The top of the board is dominated by the microcontroller itself: a 60MHz NXP LPC1768 based on the eminently capable 32-bit ARM Cortex-M3 core, sporting 64K of RAM and 512K flash, and rounded out with an embarrassment of peripheral riches: Ethernet, USB (host, device, and to-go), CAN bus, multiple serial, I2C and SPI buses, 12-bit A/D and even a 10-bit D/A converter and realtime clock/calendar. Also on top is the USB connector (mini-B), some power regulation circuitry (operating on 4.5 to 9 volts DC, or USB power), several indicator LEDs, and the reset button (a plain vanilla tactile switch on our purchased unit, not the candy-like blue button seen in product shots).

The underside conceals an Ethernet transceiver chip (requiring only the addition of an RJ45 jack to get the board on a network) and a DiskOnChip-style component that provides a small (about 2MB) FAT filesystem when attached to a host system through USB, much like a thumb drive.

This latter feature — the FAT filesystem — is half of the key to mbed’s software-free, cross-platform magic. Getting new code onto the device is simply a matter of copying the compiled program (as a .bin file) to this drive. Press the reset button, and the new code is copied to the MCU’s internal flash and run. No special programming hardware dongle, no special bootloader software, just drag and drop. This has some serious implications. Pretty much any system these days can mount a FAT filesystem. We’re not just talking about getting Mac and Linux users into the fold alongside Windows…there’s also the impending wave of featherweight netbooks with ARM and VIA chips running peculiar, instant-on operating systems. Or the OLPC XO-1. Or older PowerPC Macs. The computers in the school’s lab that you’re not allowed to install any software on. Game consoles.

The Software

“Cloud computing” is still the hot buzzword this week, and the mbed project has adopted the concept wholeheartedly, comprising the other half of their softwareless strategy. Everything with mbed — everything, even your own source code — resides on their servers and is accessed through a web browser. This carries with it all of the good and bad points of any other network-based service such as Google Docs. There’s the potential for this to be a fantastic tool for teaching and collaboration, and in fact they’ve created such an online community for mbed, with forums and publicly-shareable code libraries. One can move between home and office, or travel around the world, and resume editing code on any system with a solid ’net connection. No need to check for software updates; the server will always be current.

mbed programs are written in C++ (yes, thankfully it’s “programs” and “C++,” not “sketches” or “the mbed language”) using their JavaScript-based online editor. When ready, click the Compile button. The compiler and linker run on the back end, on the server at the other end of the network connection. Provided your code is all syntactically valid, a compiled .bin file will then be downloaded to your computer…save this to the mbed USB disk, press the reset button, and you’re good to go. In Arduino-like fashion, the mbed device also appears as a virtual COM port, so you can monitor a program’s serial output using any terminal program.

The Good

We were taught that you should always say something kind before criticizing, so we’ll point out that the above process does, in fact, work exceedingly well, and has proved to be both quick and reliable. Once you get into the groove, the sequence of operations is no more onerous than with Arduino or any other microcontroller-specific programmer dongle.

To their credit, unlike some microcontroller evaluation kits, there are no artificial limitations to the mbed compiler; the full code and memory space of the processor is available to your code. The editor has realtime syntax coloring and multiple undo levels. And double-clicking on an error message in the compiler output will take you directly to the offending line, as in any decent IDE. You can import existing code from your local system to the mbed “cloud,” or likewise export individual files or an entire project. All good stuff.

The real saving grace of this setup is the libraries, both the official functions in what they call the “Handbook,” and community-contributed code in the “Cookbook.” A tremendous amount of functionality has been implemented in a concise and usually object-oriented manner. It’s almost comical sometimes, after having worked with other microcontrollers and girding for some expected coding nightmare, only to find that the corresponding library handles a task in a couple of lines (browse through the Handbook and Cookbook for examples). There’s a tendency also to follow stdlib or “UNIX-like” conventions for file access, character I/O, realtime clock access, etc., so existing systems programmers new to microcontrollers will feel right at home, no weird function names or syntaxes.

The mbed’s FAT filesystem is also accessible to the microcontroller, making it useful for more than just program storage. Web pages can be served from this space, or a data logging program can store results here. If the two megabyte capacity is too limiting for your needs, have a look at the SDCard library in the Cookbook — it’s almost trivial to wire up and use. Pretty much all of the libraries are like that!

The Bad and the Ugly

Hardware-wise, there are just a few minor nitpicks:

First is with the local FAT filesystem. Even though this is one of the device’s most unique features, and the very thing that enables its platform neutrality, the implementation just seems a bit anachronistic. The aforementioned SDCard library demonstrates how readily that format can be used. It’s faster, with the potential for far greater capacity, and cards could be easily swapped out for different code or data files. Not a major disappointment, just seems like an opportunity was missed to make this product even better.

Second is with the indicator LEDs on the board. Four of them, scant millimeters apart, all blue…making them pretty much worthless as status indicators from across the room, where they all blur into a singular blob. Ten years ago, blue LEDs were novel. Five years ago, they were mainstream, festooning every last USB hub, mouse, flash drive and imported piece of crap. Today they’re just tired, let’s get over it. Different colors would indicate status at a distant glance.

Finally, not a problem with the mbed board itself, but it would be nice to see one of the Cookbook projects, the “BoB2” breakout board, made into an available product. The blank board can be ordered through BatchPCB, but after postage and handling the price for just the empty board — no components — is $33. Have this populated and mass-produced, bundle it with the mbed in a $100 package, and it sounds like a winning setup, ready to go head-to-head with the MAKE Controller.

But really, those are just nitpicks. Our real beef is with the software…the code editor specifically. If you find the Arduino editor aggravating, the mbed editor will have you seeing red (or maybe purple if you factor in all those blue LEDs). Like Arduino, there’s no true tab formatting; everything’s expanded to spaces, like it or not. Auto-indent cannot be disabled, and there’s seemingly no command to increase or decrease the indentation of a block of code. If you’re accustomed to anything more than arrow keys to move and click-and-drag to highlight text, the editor disregards a lot of system-native editing behaviors that may be deeply ingrained in your muscle memory (such as shift-clicking to select a range of text, or triple-click-and-drag for multiple contiguous lines). What’s more, the quirky behaviors are a little different across each browser and operating system. Don’t even try that triple-click-and-drag in Firefox for Mac…you won’t get your text cursor back without a complete reboot (seriously, just restarting the browser isn’t sufficient). And at present, only the most common browsers are supported; all others are currently shut out.

The closed-source nature of the tools may also be off-putting to some. If one finds the Arduino editor distasteful, there are options: get in there and change the code, or simply use a different editor and link with the Arduino libraries manually…it’s all legal and encouraged. With mbed, there are no alternatives. Access to the compiler and libraries is “free as in beer,” but not “free as in speech.” There’s little recourse should the service ever be taken down, or if they should suddenly start charging a subscription fee (there’s no indication this is planned, just a hypothetical scenario).

The good news, at least with regard to the former, is that software is of course infinitely more malleable than hardware, and it’s almost certain the tools will improve with time. The site is under active development…new “Home” and “Notebook” features were added for registered users just yesterday. Perhaps, given time, they’ll get the Command key working properly on the Mac. The selection of user-submitted code will expand regardless, making it progressively easier to do more and different things with this board.

In Summary

The mbed Tour page is frank about what the platform is good for, and what it’s not. mbed was intended as a quick prototyping and educational tool, and at that it excels. A lack of features such as a debugger or offline compiler keep this from being a professional-strength development platform, which is okay. Think of it as Arduino: The Next Generation. Although the mbed board costs more up front than Arduino, there are capabilities here that would otherwise require costly “shields” and strain every last byte and CPU cycle of the 8-bit ATmega328 processor: Ethernet, USB, SD cards…mbed handles these tasks with aplomb.

mbed is not without its flaws, and the “cloud” development approach may never sit right with some. For a product that’s just weeks out of beta testing, the results thus far are extremely encouraging. There’s immense potential here: a seriously powerful chip, easy to interface and to program. If the online tools can be improved, or if open source alternatives become available, mbed could be a major player. We expect to be seeing a lot more of this device in future hacks.