Google ADK On An EvalBot

August 31, 2011 by Mike Nathan 11 Comments

evalbot_google_adk

After learning that Google’s ADK relied on using an Arduino-compatible board, [Benjamin] was disappointed that other microcontroller platforms weren’t invited to the party. Rather than switch camps, he took it upon himself to get the ADK working with his EvalBot. In fact, his modifications should allow the ADK to work with nearly any Stellaris ARM kit.

The hack is composed of two parts. The first, and most important bit is the USB host driver he developed to work with the ADK. The code borrows some bits from Texas Instruments, and will be published on GitHub once he gets a chance to clean up the source a bit. To get his phone working with the EvalBot, he also had tweak the external USB power supply in order to provide the current required to operate properly with other USB-connected hardware.

It’s always nice to have more options when working with Google’s ADK, and [Benjamin’s] work is likely a welcome addition to any Stellaris developers toolkit.

Continue reading to see a quick video of his EvalBot ADK demo.

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Virtual Machine For Microcontrollers Lets You Run Python On AVR Chips

August 31, 2011 by Mike Szczys 23 Comments

[Clifford Wolf] wrote in to let us know about a project he recently completed called EmbedVM. It’s a virtual machine for AVR microcontrollers. The package has a relatively small overhead, taking up about 3kB of program memory. The VM can execute 74,000 instructions per second, and runs asynchronously from the microcontroller. As [Clifford] demonstrates in the videos after the break, this can be handy for preloading commands to prevent slowdown during heavy VM processor loads.

The snippet in the image above is an example program written in the C-like VM code which will play some [Rick Astley] on a speaker. This code can be run from RAM, EEPROM, or even external storage like an SD card. Recently there was a supplemental compiler project that even takes Python code and compiles it into VM byte-code. What a nice abstraction tool for making inexpensive microcontroller-based designs easily programmable for those that have a bit of Python experience.

If you don’t recognize the name, [Clifford Wolf] is also the author of OpenSCAD, a tool that is quite popular with 3D printing.

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VGA Video Output With An ATtiny

August 31, 2011 by Mike Nathan 5 Comments

vga_video_attiny

[Fernando] is working on creating a game at home, with live scoring displayed on a large LCD TV. He’s keeping mum as to what the game entails, but he was more than happy to spill the details on how he planned to use the television as a wireless scoreboard.

The writeup is the first part in what will likely be a substantial series of progress reports, covering how he used an ATtiny45 to drive his LCD display. Eventually, the scoreboard will use a Bluetooth adapter for wireless input, but his immediate goal was to get the display running properly.

He explains how he uses the tiny micro and its limited set of I/O pins to drive the display, dipping into some of the technical details along the way. He discusses how he worked out the timings of the VSYNC and HSYNC pulsing, as well as how how the characters are actually drawn on the screen.

The article isn’t overly heavy on the technical details, and he has sample code available so you can take a look at how the VGA magic was done, so be sure to check it out.

Vowel Recognition Using An ATmega644

August 27, 2011 by Mike Szczys 3 Comments

[Youchun Zhang] and [Annie (Wei) Dai] found a way to differentiate vowel sounds using an ATmega644 as their final project for a microcontroller design class. Voice recognition is not out of the ordinary, but most of the time it uses a computer, smart phone, or specially designed hardware. This implementation uses an ATmega644, a microphone connected via an op-amp, and a few buttons. In the demonstration after the break you’ll see that they’re outputting status data to Putty via an RS232 connection, but that’s just so you can see what’s going on inside the chip. It’s what’s doing all of the hard work.

In order to tell the difference between vowels, the waveforms of each sound were analyzed using MATLAB during the research phase. That analysis allowed the team to assemble data for each sound that contained the peaks least often found in the other sounds. Now the microcontroller analyzes incoming sound, comparing it to that data set. The analysis is snappy, happening in real-time thanks to the team’s use of the Fast Walsh Transform. It turns the sound into a set of square waves and presents them as a 64 bit sample. The result can be used as a password protection scheme, but as far as we can tell this doesn’t key to just one person, anyone who knows the vowels of the password can use it.

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Making Oscilloscopes From ARM Development Boards

August 26, 2011 by Mike Szczys 17 Comments

If you’ve got an ARM development board gathering dust in the corner of your shop, perhaps you could repurpose it as an oscilloscope. [Arend-Paul Spijkerman] was able to use an mbed and LPCXpresso as the hardware end of an oscilloscope. He didn’t use a standalone screen as a display, instead opting to push the scope readings from the hardware to a computer for display. This was greatly simplified by using StampDock as a basis for the GUI.

His circuit diagrams calls for an RS-232 connection for the LPCXpresso but not for the mbed. We’re not quite familiar enough with the mbed to know why, but perhaps those in the know can clue us in by leaving a comment. The probe connections are quite simple, each made up of a voltage divider and a pair of diodes. But the breadboard above looks much busier because it has two oscilloscope circuits built on it, and there’s a 10 MHz clock and a 4040 ripple counter which were used to provide a test signal.

Using An MSP430 For Time Lapse Photography

August 19, 2011 by Mike Nathan 14 Comments

vistaquest_keychain_timelapse_msp430

Hackaday reader [onefivefour] had an old VistaQuest VQ1005 keychain camera kicking around, and wanted to do something useful with it. A while back he hooked up a 555 timer and did a bit of time lapse photography, but he wanted more control over the process. Specifically, he desired the ability to tweak the delay between shots in a more granular fashion, as well as way to prevent the VistaQuest from going to sleep after sitting idle for 60 seconds.

His weapon of choice to get this task done was an MSP430, since the microcontroller can be found quite cheaply, and because it is relatively easy to use. He added a few header pins to the LaunchPad board wiring them up to the camera’s trigger as well as the on/off switch. When the wire connected to the trigger is pulled low, the camera snaps a picture. The wire connected to the on/off switch is always held low, ensuring that the camera is on and ready to go whenever it’s time to take a shot.

It’s a relatively simple project, but definitely useful. While there are many ways to build an intervalometer, the MSP430 is a great platform to use, especially for beginners.

Stick around to see a quick video [onefivefour] put together, showing off his time lapse rig’s capabilities.

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Bootloader Burning Basics

August 17, 2011 by Mike Szczys 7 Comments

[Charles Gantt] and a few others were having trouble burning the Sanguino bootloader to an ATmega644 chip. With some help from the [Nils Vogil] via the RepRap IRC [Charles] got it worked out and wrote a guide for burning the bootloader using an Arduino as an ISP programmer.

We’re not familiar with the specifics of the Sanguino bootloader, but [Charles] mentioned that he was unable to flash it onto the AVR chip without a resonator. The resonator serves as an external clock source for the chip. We’d bet the programming process changes the fuse settings on the chip to use an external source. Without that source, you won’t be able to communicate with the chip afterwards.

The solution just adds the resonator to the programming circuit. This should be useful when burning any bootloader using an Arduino. But it does make us wonder if there isn’t an alternative method that would let you draw the clock signal from the Arduino itself?