Spoke Ink - Persistance of Vision for your Bike

PROJECT NAME: Spoke Ink

TEAM MEMBERS:

• George Netscher
• Ryan Bartling
• Valerie LaBounta

PROJECT DESCRIPTION

Take your MSP430 for a spin with Spoke Ink!  Spoke Ink is a booster pack that attaches to the spokes of your bicycle wheel.  Using an array of 32 RGB LEDs and a magnetic sensor, this booster pack projects a bright, upright image right from the spokes of your wheel.   Using our software, you can create this image from any bitmap.

How does it work?

The Spoke Ink booster pack is just one row of LEDs! How can it create an image? The human eye creates a full image on the wheel thanks to a phenomenon known as persistence of vision.  To generate a persistant image, Spoke Ink and the MSP430 have to light up in the exact same radial position with each turn of the wheel.  And, they have to be able to do so no matter how fast the biker is going and how quickly the wheel is rotating.  This dynamic adjustment is achieved by triggering interrupts based on a small magnetic sensor that trips each time the booster pack passes a small magnet glued to the stationary part of the bicycle.

PROJECT FEATURES:

• An interactive, intermediate level project for the 430 enthusiast
• Software to load any bitmap
• Three wireless, battery-powered PCBs
• 96 RGB LEDs
• 3 Hall Effect magnetic sensors
• And hours of fun

RESOURCES:

Please, see attached zip folder for all of our code, schematics, documentation, and bill of materials (BOM). 

USER'S GUIDE:

1. Solder all the components to the custom PCBs.
2. After selecting the bitmap of your choice, pass it through our bash script (Bitmapto3ColorBitmaps) to break it into 3 component red, green, and blue images (represented as grayscale).  This is easiest done in linux.
3. Open the Image2Code executable.  Let’s start with the image generated for blue.  Drag and drop the first 8-bit grayscale image onto the executable and select left-to-right and top-to-bottom.  Uncheck the box  marked invert image and click convert.  This will create a text file with the bitmap pixel array stored as a 2D array of 8bit characters.  Write “unsigned char fromFileArray[/*add pixel count*/][/*add pixel count */] =” in front of the array.  Fill in the bracketed region with the pixel count of your image (i.e. [512][512]).  Save the text file as “fromFile.h”. 
4. Open our fromfile.c with your favorite IDE.  We used Visual Studio 2010.  Add fromFile.h to the build director or headers folder.  Within fromFile.c update XRES and YRES to reflect the number of pixels in your image (ie. 512 x 512).  Compile the code to generate a text file called “output.txt”
5. Open HALL.c, HALL.h, modulo_main.c in one project in Code Composer Studio.  Copy and paste the inner array and outer array into the arrays labeled blue and blue 2, respectively. 
6. Repeat  steps 2-4 with the red and green images
7. Plug in your MSP430 and compile!
8. Attach the 430 to the Spoke Ink Booster back and plug in the batteries.  Make sure you have already connected magnet to a place on your bike that does not rotate with the wheel and will pass the Hall effect sensor.

Spin the wheel and watch your image come to life!