Switch Pin for Filament Runout/Motion Sensor?

Wrapping up building Ratrig VCore3. Have everything running pretty good but having issue with filament sensor.

Board is SKR Pro 1.2 and sensor is the BTT SFS V1.0 Smart Filament Sensor. I have it wired to the port E0 as shown in the attached photo. In the Klipper config file i cannot seem to figure out what to use for the switch pin. See that section of config below. Can somebody help me determine what pin to put in the config and also share how you figure this out in case i run into it with other pins? Thanks!

[filament_motion_sensor my_sensor]
detection_length: 7.0

The minimum length of filament pulled through the sensor to trigger

a state change on the switch_pin

Default is 7 mm.

extruder: extruder

The name of the extruder section this sensor is associated with.

This parameter must be provided.

switch_pin: ???

See the “filament_switch_sensor” section for a description of the

above parameters.

Pe15 from the pinout