Tool/software:
I have the ADS1120. I'm trying to read from the ADC in continuous mode with a separate DRDY pin. It works as expected and perfectly fine when I read it in temperature mode (temp mode in config register 1): DRDY falls, I read two bytes from SPI and DRDY goes high, and after the expected time (50ms in case of 20 samples per second in normal mode), DRDY falls again.
When I switch the ADC to read actual data, I have two issues.
One issue is that DRDY falls much faster (microseconds instead of milliseconds), and has spikes every 160 microseconds - see screenshot of an oscilloscope snapshot. When switching from normal to turbo, and switching to different sampling rates, behavior does not change. The chip is supposed to top out at 2kHz sampling.
The second issue is that the values I'm getting are quantized to be about 12-13 values apart (e.g. 0, 12, 24, 36, 48). I verified that these are the values sent over the wire via an oscilloscope. Those readings imply that I'm getting about 12.4 bits instead of 16 (16 - log2(12) = 12.4).
The values themselves seem to be about what I'd expect, just with more quantization and much faster sampling than expected. I tried several copies of the chip (with one sourced from Digikey), all giving me the exact same behavior.
