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Reprogramming Registers in AD9914 after each frequency sweep pulse (using osk to gen pulses) generation to a different upper and lower sweep frequency in DRG mode but registers are not being reprogrammed. The sweep frequencies I set in the initial program

Question asked by analogger on Oct 31, 2017
Latest reply on Oct 31, 2017 by KennyG

I want to generate two pulses in a repetition, one long pulse and one short pulse. Long pulse must have a frequency sweep from 100 MHz to 150 MHz and 70 us ON time and short pulse must have frequency sweep from 60Mhz to 65 MHz with 10 us ON  time. Long pulse and short pulse must repeat with some time period e.g 1 msec.  I am using OSK to generate pulses. But I have to reprogramme the upper and lower sweep frequency registers and ramp rate registers after each long and short pulse respectively as they have different sweep parameters. When I initially programme the registers, they generate frequency sweep in the long pulse from 100 to 150 MHz successfully but when I reprogramme the sweep registers in the off time between long pulse and short pulse, the values in the sweep register donot update and short pulse is also generated with sweep paameters of the long pulse. Do I have to reset the DDS after each pulse to reprogramme the DRG registers for different upper and lower frequencies?  Im using FPGA to programme the DDS through Serial programming port.