Building An Analog Whistle Detection Device

August 20, 2013 by 11 Comments

Hackaday readers may remember a whistle detection device that I [limpkin] designed some time ago. As [Kevin] saw the new Staff roll call, he discovered this project and wanted to make his version of it.

In contrast with the original Whistled where all the signal processing is done in an ARM Cortex m4 microcontroler, [Kevin] uses discrete components, operational amplifiers and an Arduino Uno to detect someone’s whistle. In his video (embedded below), he goes into great lengths to explain how his circuit works along with the theory behind it. In his setup, his microphone’s signal is amplified, passed through a 1KHz-3KHz passive band-pass filter to a non-inverting amplifier with a 1000x gain (!) and finally to a voltage comparator. The Arduino measures the frequency of the signal coming out from the comparator and triggers a relay if the whistle is a ramp-up / ramp-down.

If you want to make the comparison between the two versions of the electronics, here is the link to the original whistled project.

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Sensor Gloves From Joystick Pots

August 20, 2013 by 25 Comments

joy

After working on the DARPA Virtual Robotics Challenge this summer, visions of a Heinlenesque robotic actuator filled [Hunter]’s head. His lab had access to something called a Cyberglove that used flexible pots in each of the fingers, but each of these gloves cost the lab $15,000 each.

With a little help from some joystick potentiometers, [Hunter] whipped up a decent approximation of a $15,000 device that measures how much a user’s fingers are bent. The pots are tied into an Arduino and read with analogRead(), while a small Python script interprets the data for whatever application [Hunter] can imagine.

There are a few drawbacks to [Hunter]’s design – it’s not wireless, unlike the $15,000 version, and they certainly don’t look as cool as the real thing. Then again, the DIY version only cost 0.2% as much as the real deal, so we’ll let any apparent problems slide for now.

Twitter Knitter Combines 40 Year Old Hardware With Modern Social Media

August 20, 2013 by 12 Comments

When presented with a vintage Empisal Knitmaster knitting machine, members of the TOG Dublin Hackerspace worked together to not only bring it back from the dead but to also add some custom hardware that allows for computer generated patterns.

At first the Knitmaster was in fairly bad shape requiring a few custom machined parts just to function.  It was originally designed to feed in special punch cards that mechanically directed the many moving parts of the machine (called “dibblers”) to knit patterns in yarn.  Using an Arduino, a number of servos, and a microswitch to detect when the knitting carriage is pulled across, this card-read system was replaced with a computer controlled mechanism that can direct the machine to print out images one row at a time.

Of course, you don’t get too many opportunities to name your project something as cute as “The Twitter Knitter”, so once the system was working, it was only a matter of writing some code to snatch tweets from the web and generate images out of the text.  Visitors of the Dublin Mini Maker Faire got to watch it in action as they posted tweets with a particular hashtag which the machine happily printed in yarn (as long as they weren’t too long).

Video demo after the jump.

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Update: Testing The Accuracy Of A Magnetic Rotary Encoder

August 20, 2013 by 27 Comments

A while back we featured a magnetic rotary encoder that [LongHairedHacker] designed. The heart of the system is an AS5043 magnetic rotary sensor which runs from $6.5-$11 and has a 10 bits precision. As we wanted to check if his design was really efficient, he made a test bench for it.

For 360 degrees, a 10 bits precision means a ±0.175º accuracy, which is quite impossible to check with conventional measurement equipment. The first approach he thought of was to attach a mirror to the encoders axis and point a laser beam at it. The laser beam would be reflected across the room to a big scale, but the minimum required distance would have been 5 meters (16 feet). So he preferred attaching a motor to the sensor, rotating at a given speed and measuring the sensor output.

In the first part of his write-up, [LongHairedHacker] lays the math which explains the different kinds of errors that should be expected from his setup and sensor. He then proceeds with his test, where an ATMEGA8 based board is used to send the measured position to his computer. It should be noted that [LongHairedHacker] currently uses the time spent between two received measurements on his computer as a time base, but he is planning on time stamping the data on his board in the next future. Nevertheless, he managed to measure an average ±0.179º accuracy with his simple test bench, which is very close to the manufacturer specification.

Here is the link to our original post about his sensor.

Fix A Keyboard’s Firmware With Trial, Error, And I2C

August 20, 2013 by 20 Comments

eepromKeyboardFlash

If the media shortcut keys on your keyboard don’t function correctly due to outdated firmware, the manufacturer may recommend you ship it to them for an update. [Alvaro] didn’t care to wait that long, so he cracked it open and taught himself how to mod the EEPROM. The result is a well-documented breakdown of sorting out the keyboard’s guts. Inside he finds a USB hub, which he ignores, and the keyboard controller chip, which he attacks. Two data sheets and a schematic later, [Alvaro] breaks out the logic analyzer to compare physical key presses to the keypad codes they output.

He dumps the entire EEPROM and follows up with a quick flash via I2C to change the “next song” key to instead output the letter “a”. That seems to work, so [Alvaro] combs through an HID USB usage table for some codes and has to guess which ones will properly control Spotify. He converts the media keys from “scan next” and “scan previous” to “rewind” and “fast forward.” Problem solved.

[Alvaro] had zero knowledge of keyboards prior to opening this one up. If you aren’t already taking things apart to see how they function and how to fix them, hopefully his success will persuade you to explore and learn about those “black boxes” in your home. And, if you’ve never used I2C before—or think it might be the name of a boy band—head over to [Kevin’s] tutorial on bitbanging I2C by hand.

Getting Boxeebox Root And Making It Useful Again

August 20, 2013 by 41 Comments

When it was released just three years ago, the Boxee Box – a set-top box designed to run the Boxee HTPC environment – was a pretty cool little device. Even though it was somewhat crippled from the get-go, the Boxee Box had a lot of neat features including a remote with a QWERTY keyboard, the ability to stream media over a home network, and automatic scraping of IMDB for proper info for all your torrented media. Team Boxee recently left for Samsung, and the severs have been shut down, but that doesn’t mean your Boxee Box has outlived its usefulness. Here’s a few hacks to get your Boxee Box up and running again, sent in by [Ryan].

Last year at DEFCON 20, [GTVHacker] demonstrated two ways to get root on the original Boxee Box. The first is a software root method that runs a shell script on every boot. The second is a far more elegant hardware modification that involves cutting two traces and soldering wires to a UART adapter.

Root is fine, but what the Boxee Box really needs is an update to its media player. Boxeehack does just this and only requires a USB stick for installation. Boxeehack puts back some of the default XMBC functions that were removed from the Boxee Box, and gives anyone running this media center root.

It may be old and unsupported, but there’s still plenty of life left in the Boxee Box. They’re also pretty cheap, so if you’re looking for a small media player for your TV, you might want to think about picking one of these boxes up.

Reverse-engineering Old Finnish Metro Station Displays

August 19, 2013 by 7 Comments

This project definitely was a patience tester. As the control system of the Helsinki metro was (and still is) under big renovation, [Konsta] could buy three old information displays for a very cheap price (5€ each). However, these displays came with no information whatsoever about the way to drive them, thus starting a long reverse-engineering journey.

[Konsta] started by taking one apart, discovering that each side of the display was composed of 10 daisy-chained LCD screens and some kind of control box. As you may have guessed, the key to reverse engineering the display was studying the contents of this box. It turned out that the control electronics were composed of an 8085 CPU, some RAM, a peripheral I/O chip, an UV-erasable EPROM chip (containing 32KB of program memory) and an EEPROM.

[Konsta] used an AVR to dump the memory contents of the two latter chips and it was at this part of the project that the Helsinki Hacklab joined in. Together, they reverse engineered the control PCB, studied the assembler code, sniffed the different on-board buses to fully understand how the display could be controlled.

We strongly recommend reading [Konsta]’s writeup, especially knowing that he made this english page just for us!