MCU and ADC chips communicate using SPI, with an ISO SPI isolation chip between them. There are six pins connecting the MCU and the ADC,including MISO, MOSI, NSS, CLK, DRDY,and INT. The DRDY pin is set to 1 when the ADC chip has completed data conversion. Currently, using a logic analyzer to capture these six pins, MOSI,NSS, and CLK are correct, and DRDY also sets to 1, but MISO is always at a low level. What could be the issue?
