[Alan Anderson]

I can't find the post right now, so I can't be sure I'm remembering this properly. I recall someone who should know saying that reconfiguring a pin between input and output "stalls" the FPGA briefly and can mess up other measurements.

What happens if you try connecting the sensor's signal line to a pair of GPIO lines, one input and one output? I don't know whether the FPGA ignores sidetone or if it relies on the sensor itself to not respond to its own signal.