I have read the datasheet (the datasheet of AD9910 & the user guide of the develop board )and almost all questions and answers here in detail. I just want to use the DDS to create a sin singal . But now I have a problem with the SPI communication between FPGA and DDS. I am sure the I have pay enough attation to the configure of clock , mode choice and so on. But it seem that the data was't write into the AD9910 core. IS the problem with the timing sequences? I SAW that there is a time stall between the instrction cycle and data transfer cycle , Does the time stall(delay) is essential???? thanks in advance!