Hi Sergey,
Thanks for the tips. I already tossed out the switching of power and ground due to the resistance of the analog switch. I was still possibility considering the switching between the FPGA IOs and the ADC on the Galileo still. I wasn't planning on adding another ADC, but I'd be open to opinions on that.
I've looked at a variety of sensors and have written down the common pin counts and configurations of the interfaces (SPI, I2C, etc.) For the headers, instead of having specific I2C, SPI, etc. headers, I was going to provide generic IO headers that could be configured as IO, I2C, SPI, etc using sample RTL in the FPGA. I thought that I'd keep the header signals separate instead of providing parallel interfaces since we should have enough IOs and to provide maximum performance. As it stands, I'm calculating about 40 IOs available for header pins.
Thanks again!
Matt