I am having some problems with the SPI communication between an ATMega2560 MCU and the ADS8688. The MCU only receive 0xFFFF from ADS8688 regardless of the program/command registers sent. Here is an example of the response from ADS8688 when the MCU send an Auto Channel Sequence with Reset (AUTO_RST) command (data is captured using a logic analyzer):
The hardware design can be seen below:
I have checked the signal is transmitted accurately from the MCU to the ADS8688. The Arduino library being used is obtained from: Any help is greatly appreciated.