Kakute F4 serial SBUS servo out jitter

I am trying to use free UART for sbus servo output co control some auxiliary features like headlights etc on freestyle copter with kakute f4. It works to a degree but there is a lot of servo jitter. I am using SD1 sbus to pwm decoder and it work fine from the receiver sbus but jitters a lot from UART (serial 2).
Any help?

I’m using the 4 channel FrSky sbus-pwm decoder with a Pixracer, and there is no jitter on the pwm outputs. Don’t have an SD1 to test though.

Not likely SD1 to be the only cause, since SD1 works Ok with Rx sbus out. Where do you get sbus out from pixracer? Dedicated sbus out or from serial? I am not familiar with pixracer. Thanks!

I’m using a serial port on the pixracer: