Hi! I send an SPI "read register" command from my ESP32 to DRV8301. According to graphs, command is interpreted by DRV8301 and a correct response sent, but the levels of the signal are off. This prevents the signal from being read on the ESP32 side. Oscilloscope image of MISO is attached. Lowest signal is 0v, highest ~3.3/2=1.65v, middle (what?!) is ~0.5v. The low signal seems to become non-zero only during SPI transaction (when ChipSelect is 0). Clock is ok.
SPI cables are short (2-3 inches). Voltages are:
avdd = 6.68v
dvdd = 3.33v
gvdd = 11.06v
pvdd1 = 9.98v
VDD_SPI = 3.29v
PCB is my own desing, the scheme is attached. I have tried a DRV-only setup on the PCB as well as a complete setup with DRV and all the capacitors and R's, (and mosfets). Issue persists.
The strange 3-level signals (2 pictures) are MISO, other pictures are self-explanatory.
What could be the problem?
