Today I took the code snippet from last week and started making code that actually gets information from the different ADC channels and cycles through them.
I used pages 9-14 of the ADC ADS7828 datasheet to do this. The basic communication structure of the ADC over I2C looks like:
Utilizing what the datasheet told me, I was soon able to get a reasonable response from the ADC board, but it what not the correct channel and the wrong power settings.
The connections I used to provide power and data from the expansion header on the BeagleBoard was found on the I2C tutorial and is as follows:
Since the 5V rail on the BeagleBoard droops to around 4.8V under normal conditions, I used a second power supply for the 5V needed to supply the high voltage side of the translator, the ADC board, and the IR sensors. I am unsure if the stability of the switching regulator will be a problem for acquired data stability of the ADC but I will do testing when I assemble the system.
Today I didn’t quite get my code communicating effectively with the ADC, but I am very close. Here is a link to my progress for today: