I'm having intermittent problems with reading and writing to the AD9913 with serial SPI. Is there a need to pause between the address and the data transfer? I'm running the SPI at 10MHz and have less than a 30% success rate with writing to an address, and almost 10% reading. I currently transfer all bits sequentially without any pauses between the address and data. Sometimes it seems like I can write to the CF2 to turn on the PLL, and I can read it back, with bit 0 indicating lock. However, I can't write to the FTW to change the frequency, nor can I write to the CFR1 to toggle on and off the SYNC_CLK.
Furthermore, I am using a FPGA to communicate via serial SPI to the AD9913. I can guarantee that I keep the
CS, PWR_DWN_CTL, and MASTER_RESET low during the full communication cycle. I toggle the IO_Update high for a few clks only after a write cycle. I toggle the MASTER_RESET on power up and wait for a number of clks prior to initiating any communication cycles.
If anyone was encountered similar problems and has determined a solution, please let me know.