Monday, August 20, 2012

The Journey from There to Here

I've finally decided to start a blog for the fun little side project I've been playing with lately.  So, a condensed history of how I've spent my free time over the past few months follows herein:

February of 2012, I finished my first major, publicly visible task as an engineer on TI's Stellaris Microcontroller team; I published an application note detailing how to build ARM's CMSIS DSP library using our (in the corporate sense) preferred IDE, Code Composer Studio v5.  The app note is available at and required a decent amount of work between myself and the engineers in Dallas who make the tms470 compiler to get fully running.  CMSIS uses a number of direct assembler calls and compiler intrinsic, the support for which required some work on my part.

I felt the application note was fairly well done, but I was left with a feeling of unfulfilled remorse, as I spent a very long time writing it, but never actually got to use the CMSIS DSP lib outside of the default test cases that CMSIS ships with.  As such, I started brainstorming ideas for projects that would incorporate heavy dsp functions.

I spent many years during and after college running soundboards and digital mixing/recording equipment, so I soon decided that I wanted to do something involving audio signal processing with CMSIS.  The obvious idea for me was to use the fft functionality to make the display for a graphic equalizer.  By April 2012, I had a spare lm4f232 evaluation kit in my office and seven hours' time to kill (compliments of a day of travelling for a friends' wedding), so I spent the time in the air learning how graphics lib worked and exploring the analog inputs of the 232.  The experience left me more knowledgeable but discouraged, as the 96x64 OLED just didn't look as visually impressive as I had hoped.

Around July 2012, several of my coworkers were talking about and working on the Stellaris Launchpad that will be releasing in a few months.  It took a bit of finagling, but I managed to secure an early run beta version to play with.  A bit of googling and I came across an MSP430 booster pack that Olimex released a few years ago:  In short, it's an 8 by 8 array of LEDs that uses SPI for communication.  Not nearly as much resolution as the 232 kit's OLED, but much more interesting to me.  Plus, blinking LEDs is what microcontrollers are all about!

Hardware in hand, I started to define the parameters of my project.

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