One of the problems with working with the Raspberry Pi and various peripherals is the sometimes confusing documentation. Case in point: writing C code to control the Si4703 FM radio receiver breakout board via it's I2C interface.
The Si4703 board needs to be reset (via external manipulation of its inputs) before it will drop into 2-wire mode (default for the chip is 3-wire (SPI?) mode, which the chip supports but the board doesn't). Because most of the code for the Si4703 board is written for the Arduino controller, translation to the Raspberry Pi usually involves a bit of research and (sometimes) guessing.
To make a (2-week) long story short: many thanks to Mark Kleback for providing info on the various board differences. Prior to finding his article, I'd been using the wrong pins (4 & 8) which was causing all of the I2C addresses to show up as active when checking with "i2cdetect -y 1". Using the Mark-provided info, I am now able to get the Si4703 to properly show up on the I2C bus at a single address. I can now start working on accessing the rest of the chip's functions.
Mark's article at available at: http://makezine.com/projects/tutorial-raspberry-pi-gpio-pins-and-python/
- Tim (18 Feb 2015)