I am new to DDS. We recently acquired the AD9852 evaluation board. I have been able to turn it on and operate it using the evaluation software provided by the company with the DDS connected to a desktop via a Centronics printer cable and port. However, when I attempt to initialize it using a labview code running on my FPGA and connected to the 40 pin header on the evaluation board, i get no output from the DDS. I have been using parallel IO. I have checked that my digital lines are outputting the correct signals. The funny thing is that if I initialize the board using the company software and get communication with the DDS going, and then switch over to communicating through my FPGA labview control, I can communicate and get the DDS to change output frequency. However, at some point the communication stops working. I think that the IO must get screwed up so that the reading and writing of signals is no longer synchronized. Once I reach this point no matter what combination of READ and WRITE pins I set, I can't get it to communicate again. Does anyone know the specific protocol for sending parallel commands through the 40 pin header (the J10 in the datasheet)? Any advice or help would be greatly appreciated!