I have been using the AD7147 capacitance sensor to detect objects between two parallel copper plates. I stumbled on the following strange fenomenon:
- Reading the conversion data from the chip is no problem. I read the following registers through my SPI link:
I get useful signals from reading these registers, allowing me to detect proximity.
- I have also tried reading the following registers:
Again, this works perfect. I get the same results.
- But when I try to read these registers:
I get only some fixed numbers that do not react on any proximity. I have the same problem when I read the registers from the Slow FIFO.
For some reason, I am not able to use the built-in FIFO's in the AD7147.
I believe my SPI link works fine, because reading the conversion results goes perfect.
What could cause the FIFO's in the AD7147 to malfunction?