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Bluetooth Morse keyboard assists the disabled
Written by Dangerus Prototypes   
Monday, 15 August 2011 00:00

Authors: Dangerus Prototypes

In an effort to assist computer users with disabilities limiting their keyboard dexterity, the crew at Zunkworks developed this wireless Morse code based keyboard interface device. The user keys in the desired characters using the “dot” and “dash” buttons on the left of the board and the Arduino based device converts these Morse code characters to regular keystrokes, sending them to the computer via Bluetooth. Additionally they report this device can communicate with tablets and even smartphones that support the Bluetooth HID profile.

Of course the project is open source with the schematic available on the Zunkworks site and the source code posted on Google code.

Read more:

Last Updated on Monday, 15 August 2011 01:45
Sound Card Microcontroller / PC Communication
Written by Electronics lab   
Friday, 12 August 2011 00:00

Authors: Electronics lab writes:

I developed a nifty way to send data from any microcontroller to any PC running any operating system with zero components and hardware you probably already have sitting in front of you.  Traditional interface methods (namely serial port and usb port, both have been referenced on Electronics-Lab) have drawbacks. For serial, you need a level converter IC (like a max232) and an archaic PC with a serial port, or a USB serial port adapter (many of which don’t run on Linux or newer versions of windows), and a crystal specifically chosen for transfer at a certain bit rate. FTDI makes a series of USB/serial interfaces, but they’re expensive and SMT only I don’t feel like paying even more for a breakout board just to communicate with a $1 microcontroller. Also, many ATMEL chips (most of the ATTiny series) don’t have rs232 capability built in, so you have to bit bang it in software (not fun). USB is another option, but requires a crystal and some level conversion circuitry, and isn’t supported by most small/cheap ATMEL chips. It’s built in some simple PICs (like some of the 18F series) but I don’t want to switch architecture just to send a few bytes to a PC! The V-USB project helps ATMEL chips bit-bang the USB protocol, and I’ve gotten it to work, but it’s not easy (their hello world program is hundreds of lines of code), and you have to mess with writing USB drivers or interfacing pre-made USB drivers with OS-specific solutions, it’s not fun either.

I’ve long wished there were an easier way! In this post, I demonstrate a simple way to send data from a microcontroller to a PC (and a more advanced second example showing bidirectional communication) using PC a sound card! Although the one built in most PCs would work, I decided to do it with $1.30 sound cards that are all over eBay. The chip sends pulses of data to the PC and a Python script (which can be run on virtually any OS) listens to the sound card with the pyAudio library and waits for data. When it’s received, it measures distances between pulses and dumps data values to the screen (optionally logging them to a CSV file ready for graphing by Excel or some other program).  A series of calibration pulses precede the data stream allowing the PC to adapt to incoming data at any speed (no specific clock speed or crystal is required).

Although it’s not a refined method suitable for consumer applications, it sure is a useful hack for anyone looking to quickly exchange data between a microcontroller and a PC!

Sound Card Microcontroller / PC Communication - [Link]

Last Updated on Thursday, 11 August 2011 21:39
PIC32 drives SID audio chip
Written by Administrator   
Thursday, 11 August 2011 00:00

Markus shared his latest SID player in the project log forum:

A SID player emulation running on a PIC32, the sound is generated by a hardware SID chip.  A great project for any one who remember the Commodore 64 sound. And there are more then a few web site to get music to play.

Read more : [link]

Last Updated on Thursday, 11 August 2011 01:09
24 LED Police Flasher
Written by Electronics lab   
Wednesday, 03 August 2011 04:35

Authors: Electronics lab

Dual color (4 line x 3 column) led, 12 white and 12 blue are intermittently switched controlled by two NPN transistors BC337.  The speed and duty/cycle timing of lighting duration is determined by NE555 oscilator. The number of repetition of sequential lighting of each group of led is determined by 5-stage divide-by-10 Johnson counter with 10 decoded outputs and carry out bit (CD4017).

The intermittent lights from two group of led imitate the police car strobe lights.
The speed of switching off and on of led are continuously regulated by variable trimmer resistor.

24 LED PoliceFlasher - [Link]


Last Updated on Wednesday, 31 August 2011 00:52
RFM12B range testing
Written by jee labs PhC   
Monday, 01 August 2011 00:00

Authors: jee labs PhC

Dsc 2513

There have been many questions and discussions about the range achievable with the RFM12B wireless modules. Usually, my answers have been: 1) should be about 100m outside, and 2) gets through about two walls inside the house. But the most accurate answer really is a resounding “it depends” …

Because it really does. RF range will depend on a huge number of factors. What works for me may not work for you, and what works today may not work tomorrow.

Triggered by some recent discussions on the forum, and with the help of Steve Evans (@TankSlappa) who wrote a good set of sketches and did some tests, I’ve come up with two sketches and a setup to report reception quality.

Last Updated on Monday, 01 August 2011 01:30
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