The OpenServo Project

January 28, 2011 by James Munns 13 Comments

When it comes to using servos in projects, there is a definite distinction between the cheap ones and the expensive high power and precision models. The OpenServo project gives you a couple options for enhancing your servo experience. By replacing the control board with a new one based on a familiar microcontroller, a whole new set of features can be attained. For those of you out there with a need for servos like these, you can buy the pre-built replacement board (unfortunately sold out right now), or build your own from the provided schematic, BOM, and source code.

Zipitbot

January 20, 2011 by Mike Szczys 22 Comments

[Nulluser’s] Zipit was fine, but it couldn’t go anywhere on its own. Adding some motors and a microcontroller fixed that issue, and now he’s got a little robot called the Zipitbot. That’s a dsPIC board on top which communicates with the Zipit over an I2C bus. Four servo motors provide plenty of power to the wheels,with some extra battery packs nestled between them.

Since the Zipit is running Linux, and already has WiFi hardware, it’s not too hard to add Internet control. With this in mind there’s a webcam on the front to broadcast a video feed for use when controlling it remotely. See a couple of videos of this hack after the break.

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Playing Piano With Optical Sensors

October 7, 2010 by Mike Szczys 16 Comments

[Sebastian] is trying to improve the responsiveness of an electric keyboard. He was unsatisfied with the lack of adequate sensitivity to keystroke. The first step in his process was to measure how fast the quickest keystroke actually is. By setting up an LED and phototransistor and taking some measurements he found that sampling at 1 kHz would be more than adequate.

With initial testing complete he ordered some CNY70 transmissive/reflective light sensors that can be place below the keys. He measures the sensor with the ADC on an ATmega16 microcontroller. Running at 16 MHz he can sample each of the eight analog-to-digital converter channels at 1202 Hz. After doing a bunch of math he put together some lookup tables that are used to translate the ADC data into midi signals. We’ve embedded a video of one sensor controlling the midi program PianoTeq. [Sebastian] also sent us a schematic of one node in the sensor network (see it after the break).

When everything is said and done he plans to use eleven ATmega16 microcontrollers to address the 88 keys, with an additional microcontroller to act as the master using a two-wire interface for communications.

Update: [Sebastian] put up a webpage with a fairly verbose description. Reading it straight from the source really clears up a lot of questions.

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Small And Simple FM Radio

September 21, 2010 by Mike Szczys 23 Comments

[gpsKlaus] built this little FM radio (translated) based on the AR1010 IC. That chip is controlled via I2C by an ATtiny45 microcontroller. His tuning implementation relies on presetting 16 stations in the firmware and selecting them with the white potentiometer.

The FM chip came on a breakout board from SparkFun. Not bad at around $15 as it includes the crystal, some caps and a few resistors, and you don’t have to try and solder to the fine pitched pads on that minuscule package. We’re a little unsure of the features included in the part as the datasheet is lacking in detail and the reference datasheet that SparkFun includes in the description is obviously for a much more full-featured chip. Still, this would be a fun thing to play around with if you’ve grown tired of blinking LEDs.

If you don’t want to let an integrated circuit do all the heavy lifting try this post for a guide on building your own radio tuner.

Graphic Calculator As A Spectrum Analyzer

July 29, 2010 by Mike Szczys 9 Comments

[Michael Vincent] turned his TI-84 Plus into a spectrum analyzer. By running some assembly code on the device the link port can be used as an I2C bus (something we’ll have to keep in mind). After being inspired by the cell phone spectrum analyzer he set out to build a module compatible with the calculator by using an I2C port expander to interface with a radio receiver module. Now he can sniff out signals between 2.400 and 2.495 GHz and display the finds like in the image above.

[Thanks Cecil]

Cathode Ray Tube Leads The Way On This Bot

May 18, 2010 by Mike Szczys 32 Comments

[Daqq’s] latest creation is this little robot with a CRT mounted on the front. Obviously ‘why?’ is the wrong question here, but we know this is right up his alley considering his propensity for the less common like this plasma ball Nixie tube. The solidly-built bot uses two stepper motor controlled wheels and an omni-wheel on the front to create a trike. An ATmega128 controls the system but the real story here is the CRT. It requires a hefty voltage regulator for the -600V to +200V the Tungsram DG7-123 tube needs. Trouble along the way ranged from dealing with stray magnetic fields from the power supply, to mounting the fragile tube itself. Take a look at his detailed writeup linked above and join us after the break for the demo videos.

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Wii Motion Plus Direct PC Interface

February 1, 2010 by Mike Szczys 7 Comments

You can pick up a Wii Motion Plus module for under $20 and that’s not bad for an I2C gyroscope. This hack taps into the device through a PC parallel port. The connection calls for some level conversion to step down to the 3.3v needed by the module. The communication protocol borrows from the Wii on Arduino code examples that we saw last year. You can see the Wii Motion Plus controlling a virtual cube in the video after the break.

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