Using Periferals with ESP32 Feather

#include 
Servo SG92R;
int pos = 0;

// PWM is possible on all 18 GPIO pins
int servoPin = 21;

void setup() {
    // Allow allocation of all timers
    ESP32PWM::allocateTimer(0);
    ESP32PWM::allocateTimer(1);
    ESP32PWM::allocateTimer(2);
    ESP32PWM::allocateTimer(3);
    // SG92R operating frequency is 50Hz
    SG92R.setPeriodHertz(50);
    // min and max pusle width settings for SG92R are 500 to 2500 microseconds
    SG92R.attach(servoPin, 500, 2500);

    Serial.begin(9600);
}

void loop() {
    for (pos = 0; pos <= 180; pos += 1) {  // goes from 0 degrees to 180 degrees
    // in steps of 1 degree
    SG92R.write(pos);  // tell servo to go to position in variable 'pos'
    Serial.println(pos);
    delay(10);  // waits 10ms for the servo to reach the position
    }
    for (pos = 180; pos >= 0; pos -= 1) {  // goes from 180 degrees to 0 degrees
    SG92R.write(pos);                  // tell servo to go to position in variable 'pos'
    Serial.println(pos);
    delay(10);  // waits 10ms for the servo to reach the position
    }
}