Hi AQ,
Thank you for providing the snapshot, and I would like to inform you that I am still working on your issue. We never face this issue before, and I am stuck right now. We might need your help to get a better understand on your end. Could you provide me a complete waveform of the SPI communication? On your snapshot #5, could you please zoom in when the CS takes “LOW”? I would like to see if there is a pulse on the data line.
I tried to duplicate your setup. The only difference between yours and mine setup is that I inserted the LM95172 and bypass caps inside the oven not a complete board setup. Since you placed your board inside the oven, could you make sure that your discrete components can handle at high temperature?
Here are some of my snapshot pictures.
Channel 1 => CS
Channel 2 => SCLK
Channel 3 => SIO
Channel 4 => Vdd
Vdd Ramp Rate at 190°C. I noticed that your Vdd ramp rate seem to be brutal.
I turned power off and on at 190°C, and it was still working. If you look at the first 16-bit, the temperature turned out to be 194°C. I even ramped up to 197°C, and nothing seems to be suspicious.
When you give me a complete waveform of the SPI communication, I will try to generate a similar waveform to see anything comes up.
Aaron