I need to generate short single tone pulses (150MHz) with a fixed pulse repetition interval (1KHz). I'm using RAM profiles on the official eval board. I did this way:
- FTW set to 150 MHz
- Matched latency, auto clear phase accumulator enabled
- RAM enabled with:
- Profile 0 Direct Switch full amplitude
- Profile 1 Direct Switch null amplitude
I have a PWM (1KHz period, very short duty cycle) connected to P1 profile pin. In PWM active phase profile 0 is selected, the 150MHz pulse is generated. In PWM non active phase profile 1 is selected and no signal is generated. Something is wrong with the transition between profile 0 and 1 though. A sort of glitch in the phase is visible in the final part of the 150MHz pulse:
Apparently this is due to the "matched latency" setting. If I disable that, final part of the pulse is perfect, but the glitch on the phase appears now in the initial part:
Is there any way to completely get rid of the glitch?
Note that I'm using the two profiles toggling because I want to generate a tone with phase starting at 0. Auto-clear of phase accumulator does the job when profile is changed. Maybe the same result is achievable in a different way?
[edited by: Carlo at 2:37 PM (GMT 0) on 3 Aug 2020]