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Published on: September 22, 2013 / Comments: None

Attiny 2313 V-USB Media Volume Control

I know this awesome project is a few weeks old but I’m going to use the fact that Rupert recently posted an update as my excuse to share it on hackalizer. As the title implies the V-USB Media Volume Control project is using V-USB. V-USB is software which makes it possible to add low-speed USB to almost any AVR microcontroller without any additional hardware.

Inside Volume Control EnclosureFrom selecting the perfect rotary encoder to designing and etching his own PCB and eventually making a custom enclosure, this project shows is all. Rupert explains some of the minor but important differences of the rotary encoder such as the number of detents and amount of force required to turn the knob and press the button.  He also shares an important lesson on load capacitance with regards to the crystal on his home-brew board. Check out the build video after the break.


Published on: September 12, 2013 / Comments: None

Simple logic analzyer using an ATTiny2313

All too many times we end up creating a tool out of necessity.  Joonas was looking for a simple way to decode PS/2 keyboard data for another project.  So he decided to build a simple logic analyzer that would let him inspect the signals.

The build uses a ATTiny2313 microcontroller, connected to a FTDI USB-to-UART adapter.  On the software side it’s real simple, open up a serial port and capture the serial data.  The data can then be plotted in OpenSniffer and visualized graphically.  One of the downsides to this project is the data rate is pretty low which is estimated at sub 100khz.

Source code is available up at Joonas site.

Published on: September 9, 2013 / Comments: None

Use an Arduino USB host shield to add a display to a USB scale

Believe it or not there’s actually a USB Host shield for the Arduino.  The shield and accompanying libraries will let you communicate with USB client devices… like this USB digital scale.  Normally this USB digital scale is plugged into a PC which will read the weight (I assume for weighing packages for mailing).

Oleg decided to to add an LCD to the device so it could be used stand alone.  He’s using your run-of-the-mill 16×2 hd44780 compatible display, an Arduino, and the USB Host shield.  The scale reports itself as a HID device to the host but still a little reverse engineering was needed to extract the weight information from the HID report.  Once the target packets were identified, Oleg whipped up a sketch to read the USB report packets and throw the info out to the LCD display.

I probably wouldn’t have the patience for doing it this way, I would have tried to open it up and read data from one of the sensors directly, but this hack just introduces you to another vector of modification or input method.  For instance using a USB joystick or flight stick with the USB host shield might be a great addition to a flame-throwing robot or something (lol).

Source sketch and more info here.

Published on: September 8, 2013 / Comments: None

Lazy Sunday Links – 9/8/2013

It’s sunday, time for a barrage of quick links.

First up, muxberrypi.  Control your Raspberry Pi via node.js and websockets.  Similar to the heimcontrol.js project.  Source repo here.  Video below.


A quick acetone vapor bath rig made from goodwill parts.  Image tutorial here.  The end results didn’t turn out that good, but I have faith in the process.  Tutorial is brief but you can get the idea.



Build a mini USB powered soldering fume extractor.  Steps here.  Can also be used as a personal cooling agent when you get really hot.  Good to have with that USB soldering iron.

OpenWRT support has been added for the Raspberry Pi.  Source repo here.  Might end up being a quality distro for turning your Pi into a router.  OpenWRT is pretty well established, I appreciate they already made the decision not to include XBMC in it.

Looking to make battery powered devices ?  Then you should probably learn more about batteries.  Calculating Amp Hours, Capacity testing, etc.

And finally, a quick crash course to programming the serial port in windows and linux.

Published on: September 6, 2013 / Comments: None

Reducing the noise on your RTL-SDR

The guys over at SDR for Mariners put together a nice writeup on reducing the electrical interference on the good ol’ cheap RTL-SDR dongle.  When the signal you’re looking for is very faint, you need to remove all of unwanted noise or else your signal gets difficult to separate.  In their case the unwanted signal is in the form of FM radio.

Even if you aren’t a big RF nerd you know some of these remedies already like ferrite beads (you know those giant blocks on the ends of the expensive cables!).  But I’m actually surprised at some of the other ones.  I would have thought that the metal connector around a USB cable would help prevent noise, but according to their tests it was acting like a collector for their intrusive FM signal.  By removing the shield and just connecting the data pins they dropped the noise by 10db.  Not using the extension cable and just plugging straight in is even better.

So the winning combo appears to be all of their methods tested.  A stick wrapped in aluminum foil, touching the metal of the USB plug, connected by a USB extension cable, inside a metal housing.

I’d love to see a picture of the final setup.  Good tips to know when chasing down a faint signal.

Published on: August 29, 2013 / Comments: None

Designing the openSip+puff handicap controller

Jason has a working prototype for what he calls a openSip+puff.  It’s meant to be a controller for people with disabilities.  It will allow you to do things with your mouth by sucking in air and blowing out air.

It uses a pressure sensor and an ATmega32u4.  It connects as a USB device so it can end up being a keyboard or mouse device (or some sort of button trigger or joystick).  I think the code is still being hashed out but he’s making good progress.

It’s open source hardware, and he’s hoping to do a Kickstarter soon.

Check out the rest of the article and source code here.

Published on: August 9, 2013 / Comments: None

The journey of building a custom chording keyboard

No not a musical keyboard, you know like QWERTY with … well chords.  Mathias is looking to speed up his productivity on the keyboard.  Some people just switch to DVORAK (which he looked into) but he decided he wants to make a special keyboard.  When you read his article you will discover his journey of ideas and options, but to shoot to the end, he decided to make a HID device using a Teensy.  The Teensy is a awesome arduino compatible microcontroller that is pretty good at making usb devices.

Anyway, the project isn’t complete yet.  He does have some preliminary source code up and some test code, but it looks like he’s working on the meat of the project (the keys) next.