Provide Pixhawk with RSSI from FrSky XSR


I’m having trouble configuring Pixhawk to accept PWM RSSI signal on Pixhawk’s SBUS pin. As I understand, Pixhawk accepts two kinds of RSSI - one is whern RSSI is provided on one of RC channels and the other one is when RSSI is provided on one of the pins as analog voltage. But in this case I need to connect FrSky’s RSSI pad (near antenna, undocumented…), which is providing PWM, to Pixhawk’s SBUS, which is (as I understand) intended to read RSSI w/analog voltage reading…

Maybe I’m wrong somewhere, please, correct me. Thank you beforehand.