I'm using the AD9910 DDS to generate a chirp waveform.
To do this I configure the AD9910 in DRG mode in no-dwell high operation.
After that, setting the Digital Ramp Limit register, the Digital Ramp Step Size register and the Digital Ramp Rate register I can choose the characteristic of the waveform (ramp limits, ramp rate, ramp step).
To start the chirp generation I use a positive impulse on the DRCTL pin.
Analizing the output of the AD9910 I noticed a strange behaviour.
If I want generate a chirp with a duration of 32 us every 100 us the AD9910 generate two consecutive ramp every DRCTL impulse, while I expected only one ramp every DRCTL impulse.
Can someone explain me if I have missed something to do or how I can avoid this behaviour?
Thank you for your help!