Hi Eduardo,
meanwhile I have finished hardware-design, and I received my first boards fully populated. Interfacing the DDC232 without FPGA works fine, and I get reasonable results.
But I´m facing a big problem: with no signal applied to the inputs of the chip, digital output signal is always at negative full-scale (-4096) for all channels. When light is applied to my photodiodes, the inputs leave negative saturation after I increase light to a certain value. I also can reach fullscale values, when I increase light input -> data-conversion works fine.
When I remove the current-divider ground resistor (15R), the digital output signal approaches values around 0 (-+1000) --> seems OK.
So I assume that the big negative offset comes from problems in the grounding. Perhaps You could take a look at the layout of my PCB? Would be a great help for me.
Thank You and regards,
Kaspar
