Prolific Hack a Day author [Mike S] has been playing in his lab again and he’s come up with a neat way to talk to microcontrollers with an LCD monitor. The basic idea behind [Mike]‘s work isn’t much different from the weird and/or cool Timex Datalink watch from the 1990s.

Despite the fancy dev board, the hardware is very simple – a photoresistor is pointed at a computer monitor and reads bits using Manchester encoding. The computer flashes a series of black and white screens thanks to a simple Javascript/HTML page, and data is (mostly) transmitted to the micro. [Mike] says he has about a failed message about 60% of the time, and he’s not quite sure where the problem is. He’s looking into another kind of Manchester encoding that uses samples instead of edges, so we hope everything works out for him.

This build is very similar – and was inspired by – an earlier post about microcontroller communication with flashing lights. Still, [Mike]‘s build reminds us of the strangely futuristic Ironman watch we had in ’97. Check out [Mike]‘s demo of his computer/micro comm link after the break and his code on github.

The usual way send data from a microcontroller is either over RS-232 with MAX232 serial ICs, crystals, and a relatively ancient computer, or by bit-banging the USB protocol and worrying about driver issues. Not content with these solutions, [Scott] came up with sound card μC/PC communication that doesn’t require any extra components.

[Scott] bought a cheap USB sound card dongle on eBay (although a built-in sound card will do) and wired up the tip and ring of the plug to the microcontroller. The data is sent from the microcontroller a lot like Morse code – a short gap between pulses is a zero, a long gap is a one. This is parsed by a Python script using PyAudio. Synchronization, timing, and calibration is automatic because of a 10-bit ‘packet header’ explained in this video.

After he had a really great way of sending data from a microcontroller to a PC, [Scott] asked himself if it would be possible to have bidirectional communication. Using the same sound card setup, he managed to get bidirectional communication off an ATtiny44a. You can see his demo video of this here.

The cleverness of hack is overwhelming, and we’re kind of amazed that this technique isn’t in the standard repertoire of solder monkeys. After looking at this, we’re tempted to throw out the half-dozen USB/RS-232 adapters we have lying around. They never worked anyway. Check out [Scott]‘s highly informative video of his build below.

[follower] prototyped a 2-line external display for his Nexus One using an Arduino with a USB Host Shield, and the Android Open Accessory Protocol. There are two basic software pieces at work: an Arduino sketch that handles displaying data sent from the phone, and a lightweight android app to detect the presence of the external screen and send data to it. As shown here, it diplays the time and the beginning of the most recently received SMS message.

This project coalesced from several other things [follower] had been working on with regards to USB accessories, background services, interfacing with the Arduino and handling SMS messages, so it’s modular and open-source.  If you’re interested in mashing up microcontroller projects and your android phone, there’s plenty of stuff in this project to help you get off the ground.

As hacks go, this is very much a “because you can” sort of deal that’s designed to tie a bunch of cool things together. You’re unlikely to catch us carrying an LCD and breadboard around in our pockets any time soon, but it paves the way for some potentially fun phone accessories.

Hackaday reader [Louis] wrote in to call our attention to a neat project over at Kickstarter that he thought would interest his fellow readers. The AlienCortex AV is a pre-built FPGA board from [Bryan Pape] with gobs of ports and a ton of potential. At the heart of the board is an Xilinx PQ208 Spartan 3e 500k FPGA, which can be configured to perform any number of functions. The board sports a healthy dose of analog and digital I/O pins as you would expect, along with PS/2 inputs, VGA outputs, and even a pair of Atari-compatible joystick ports.

The AlienCortex software package allows users to easily load projects into the FPGA, which can run up to four different emulated microcontrollers at once. The software comes with half a dozen pre-configured cores out of the box, with others available for download as they are built. The default set of cores includes everything from a 32-channel logic analyzer, to a quad processor Arduino-sketch compatible machine.

Now, before you cry foul at the fact that he’s emulating Arduinos on a powerful and expensive FPGA, there’s nothing stopping you from creating an army of whatever microcontrollers you happen to prefer instead. We’re guessing that if you can run four Arduinos on this board at once, a good number of PICs could be emulated simultaneously alongside whatever other uC you might need in your next robotics project. A single board incorporating several different microcontrollers at once doesn’t sound half bad to us.

The team at Leaf Labs just released a new library to demonstrate the VGA capabilities of their Maple dev board. Although it’s only a 16 by 18 pixel image, it shows a lot of development over past video implementations on the Maple.

The Maple is a great little Ardunio-compatible board with a strangely familiar IDE. We’ve covered the Maple before. Instead of the somewhat limited AVR, the Maple uses an ARM running at 72MHz, making applications requiring some horsepower or strict timing a lot easier.

We’ve seen a few projects use the increased power, like a guitar effects shield. It’s possible the Maple could be made into a game console that would blow the Uzebox out of the water, but we’re wondering what hackaday readers would use this dev board for.

Watch the video after the jump to see how far the Maple’s VGA capability has come after only a few months, or check out Leaf Lab’s Maple libraries.

For some projects, it’s okay to have a microcontroller twiddling it’s thumbs most of the time. When a project requires the cpu to do just one thing over and over, there’s no loss with inefficient code – it either works or it doesn’t. However, if a project requires a microcontroller to do several things at once, like reading sensors, dimming LEDs, and writing serial data out, cpu utilization can become an issue. [Robert] wasn’t happy with the code he used to control a string of LEDs, so he rewrote his code. With the old implementation, [Robert]‘s code used 60% of the cpu time. With the new and improved code, the cpu was only busy 8% of the time.

The code works by using a hardware timer to trigger an interrupt. After calculating the next time it should run again, and changing the state of the data line, the code just sits quietly until it’s needed again.

It’s not a pretty hack, or even one you can hold in your hands, but [Robert]‘s determination in getting a μC to do what he wants is admirable.

The original iPod shuffle was a pretty small device, there’s no doubt about that. However, in the world of miniature audio players, [Chan] is no slouch either.

A few years ago, he set out to construct a micro audio player that used little more than a small microcontroller and a microSD memory card. He chose an ATinyX5 series microcontroller to run the show, utilizing its pair of PWM output pins to directly drive the speakers. Since there is no built-in amplifier, the audio volume is not loud, but it does sound reasonable if you use a set of high efficiency desktop speakers. He does mention that the sound can easily be amplified after passing the signal through a filter, so there is hope for those of you who like your music turned up to 11.

The only downside we can see is that the audio player can only process Wave files, but it’s hard to expect more from a DIY audio player smaller than a postage stamp. It would be great to see what sort of micro-handiwork [Chan] could perform if he were to update his design and build a full-functioning MP3 player based upon this project.

Here at Hackaday, we see microcontroller based projects in all states of completion. Sometimes it makes the most sense to design systems from the ground up, and other times when simplicity or a quick project completion is desired, pre-built system boards are a better choice. We have compiled a list of boards that we commonly see in your submitted projects, split up by price range and with a little detail for reference.

After reading our list, sound off in the comments or on this forum post, and we may include your board in a follow-up guide at a later date. We will also be giving away 10 Hackaday stickers to the most insightful, the most original, and most useful advice given on the forum, so if you haven’t registered yet, now would be a perfect time. Winners of the sticker giveaway will be selected from the forum thread, and the final decision for prizes will be judged by the wit and whim of the Hackaday writing team. More prize details to follow in the thread. Read on for our guide based on past project submissions.

The Cheap ($0-$50):

When it comes to cheap boards, users can expect a simple breakout board, usually with some debugging facilities and minimal extra components. These boards tend to be aimed at hobbyists and the education crowd rather than companies who can afford full featured development setups for their engineers. Unfortunately, boards that come directly from manufacturers tend to have locked down or overly simplified IDEs or debugging software, though low price points often inspire the open source communities to write their own to take advantage of all the features.

• TI’s MSP430 Launchpad: Coming in at $4.30, TI’s Launchpad board is definitely a bargain. For your money, you get a set of 16-bit MSP430 processors, a mini-USB debugger and programming interface, and a set of Windows IDEs to choose from. Not much more to write home about, but we have featured a number of projects with this family of microcontrollers running the show.
• STMicroelectronic’s Discovery: Costing you a paltry $11.85, This 32-bit ARM processor may be one of the best performance to cost values. Similar to the Launchpad, the Discovery has a mini-USB interface, a breakaway programmer and debugger, and a few locked down IDEs to select. For students or professionals looking for experience with the ARM architecture, this Cortex-M3 based system would be a great place to start.
• The Arduino Family: Needing no introduction, these 8-bit AVR based systems have been displayed by us numerous times. Due to an open source hardware and software design, these boards are available for as low as $20 or so for Arduino Compatable clones, or any price range up depending on included peripherals. Because of the simple IDE and coding environment familiar to anyone familiar with C, C++, or Java, the Arduino is a common choice for beginners, non-engineering types, and professionals alike.

Mid-Range Boards ($50-$150):

For a little more money, more can be expected from a development board. Often featuring higher I/O pin counts, more complex interfaces such as host USB ports, Ethernet, or Video-Out, these boards are a great place for a little computational and functional muscle. However, with a higher cost, it is more difficult to just throw one of these boards at any one-off project. More costly boards are often supported better as well, because they are used by engineers who will decide on important purchasing decisions. This area is also a transition area from more hardy microcontroller type boards into the more powerful microprocessor type systems (such as shifting from the Cortex-M to the Cortex-A series of ARM processors).

• The Arduino Mega: For all the same reasons as the original Arduino, the Arduino Mega has its place in a prototyping or development environment. For a bit more money than the original, extra code space, processing power, and I/O pins are gained, with the same comfortable, familiar, and similar development tools. The Arduino Mega runs at $65, which makes for a costly 8-bit system.
• The Chumby Hacking Board: An interesting example of a product going from production to prototyping as an afterthought, this board is based on the guts of the Chumby One, featuring a 32-bit Freescale i.MX ARM processor at 454 MHz. This system has video out, as well as a trio of USB ports for all the peripherals you can find or write your own drivers for. The Chumby Hacking board clocks in at a reasonable $90 or so, though supplies seem to be dwindling, so act fast if interested.
• The Original BeagleBoard: At the top of the price range, the BeagleBoard (Revision C4) features a 600 MHz Cortex-A8 ARM processor capable of running a number of Linux systems, including Angstrom and Ubuntu. Designed to interface with cool toys like touchscreens, this board also features a powerful DSP chip for crunching numbers, as well as processing video and sound. For a newly discounted rate of $125, this compact powerhouse could be yours.

The Upper Crust ($150+)

At this price range, these boards often contain ARM processors from the Cortex-A series, and have more in common with high-end smartphones than the microcontrollers usually seen on Hackaday and in day-to-day life. Boards like these are a real investment, and often cost and perform similar to many older or low-end PCs and netbooks at a considerably more efficient performance to power use ratio in most cases. These boards tend to run Linux-based operating systems, including Android as well as others.

• The BeagleBoard xM: Coming in at just around $150, this big brother to the first BeagleBoard adds parts such as onboard Ethernet, an additional 2 USB ports, and a bump to a 1 GHz processor. Although the MSRP is listed at $149, a high demand has pushed the cost well above that at places where stocks are even available. Because of a strong similarity to the original BeagleBoard, the existing community is strong, and full of examples and guides to get the board going
• The PandaBoard: With features as far away from an 8-bit microcontroller as imaginable, this board comes dressed to the nines featuring a dual-core 1 GHz processor capable of handling 1080P video stream. We realize this is probably out of the ballpark of just about any “hack” level project at $174, but we know there are some engineers out there very excited to see this.

In Summary:

We know that brand and experience preference can be a strong motivator, so be productive with your advice and sound off in our forum with your picks for our follow-up post(s). We will do our best to wrap up all the information you provide into a more definitive, and hopefully even more informative guide for beginners and professionals alike.

We’ll just say, [Kenneth] really likes clocks. His most recent is a pure 7400 series TTL based one, ie no microcontroller as seen in the past, here, here, and here. The signal starts out as a typical 32,768 crystal divided down to the necessary 1Hz, which is then divided again appropriately to provide hours and minutes.

As far as TTL clocks go, this is nothing too original; until it comes to his creative button interface. By using a not as sexy as it sounds multivibrator, he can produce a clean square wave instead of the figity signals produced from buttons to advance and set the time. Like always, he also provides us with a thorough breakdown of his clock, after the jump.

[Rahul Sapre] sent us a guide to porting EFSL to any microcontroller (PDF). The Embedded Filesystems Library adds FAT support to C compiled microcontrollers. It is targeted at the AVR line of chips but can be adapted to any architecture that works with a C compiler. [Rahul's] guide will take you through the process of adapting the latest stable 0.2.8 version to new hardware by using a PIC uC as the working example. The non-stable development branch of EFSL is working toward multiple-platform support so consider lending a hand if this interests you.

A complete microcontroller development kit for little more than the cost of a bare chip? That’s what STMicroelectronics is promising with their STM8S-Discovery: seven dollars gets you not only a board-mounted 8-bit microcontroller with an decent range of GPIO pins and functions, but the USB programmer/debugger as well.

The STM8S microcontroller is in a similar class as the ATmega328 chip on latest-generation Arduinos: an 8-bit 16 MHz core, 32K flash and 2K RAM, UART, SPI, I2C, 10-bit analog-to-digital inputs, timers and interrupts and all the usual goodness. The Discovery board features a small prototyping area and throws in a touch-sense button for fun as well. The ST-LINK USB programmer/debugger comes attached, but it’s easy to crack one off and use this for future STMicro-compatible projects; clearly a plan of giving away the razor and selling the blades.

The development tools are for Windows only, and novice programmers won’t get the same touchy-feely community of support that surrounds Arduino. But for cost-conscious hackers and for educators needing to equip a whole classroom (or if you’re just looking for a stocking stuffer for your geeky nephew), it’s hard to argue with seven bucks for a full plug-and-play setup.

[thanks Billy]

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.

[Raul] built a CNC hot wire cutter that he uses for cutting shapes out of foam. His device uses two flat bed scanners to provide two planes of motion. One scanner arm has the foam mounted on it and provides the Y-axis movement. The other scanner has the hot wire mounted on it and provides the X-axis movement. The cutting wire is mounted on a flexed bow made from heavy gauge coat hanger wire.

He tapped into the logic board of one scanner to gain access to the motor movements. The other is connected through a couple of H-bridges. Both are controlled by an Atmel AVR ATmega128 which in turn takes its commands from a connection with a computer printer port. A python program uses vector graphic files in SVG format and traces the outline for cutting.

We’ve got a video of this in action after the break. At our request, [Raul] took some time to post a set of pictures and make comments on them. Thanks for the hard work and great job!

We’ve been watching the development of the snega2usb since it’s debut on Hackaday. Now it’s grown up and is ready to be manufactured. In the low quality video above [Matthias] shows some of the latest high quality additions to the board. It now has a case, shiny new firmware,  production made PCB, and game pad ports.  The snega2usb is shipping this December for those who preorder now.

The guys at Nerdkits have put together this tutorial on connecting a PS/2 keyboard to a microcontroller. Though this tutorial is written for one of the kits they sell, you should be able to apply this to pretty much any microcontroller. It is also a lesson in using interrupts instead of polling. They have several pre built examples ready to download as well as source code for the basic setup.

[via HackedGadgets]