I am testing SPI bus on Zedboard, If booted from Linux, and read or write SPI registers, everything is OK. But when I read profuct ID via SPI bus connected with FPGA, and then with external MCU, values from register are not correct. Also I captures the waveforms of SPI_CLK, SPI_ENB, SPI_SDI and SPI_SDO pins on AD9361 in both test cases, the input signals, SPI_CLK, SPI_ENB, SPI_SDI are correct and is consistent with the datasheet, and SPI_SDO is also correct when booted from Linux, but incorrect waveform of SPI_SDO when configured by external MCU. The votage on board is also good and matched in both cases. Could you please help me how to solve this problem?