Working with the Parallax Propeller Professional Development board and the Logos Electromechanical RGB Backpack. Attempting to recreate the I2C connectivity I accomplished with the Arduino. So far - NO LUCK.
At a high level I have attempted to modify a couple different I2C objects from the exchange, and use demos to communicate with the backpack - however the backpack pulls the SDA low and holds it there.
Without the backpack attached, my logic analyzer did report valid I2C data coming out of the Prop and decode it as I expected based on what I sent; this was uni-directional however - no ACK.
BTW - the Propeller also introduced the need for a level shifter, Frys had the MOS-FETs required so that looks good.
Next Steps - Focus on I2C understanding and perhaps other hardware to interface. Checking out the 'kickstarts' examples next...