// Reference Library
#include <ESP32Servo.h>

// Set two Servo motors
Servo servo1;
Servo servo2;

// Set each signal for each PIN 
const int POT_PIN     = A2;
const int SERVO_PIN_1 = D9;
const int SERVO_PIN_2 = D8;

// Set Potentiometer value
int anavalue = 0;

void setup() {
  Serial.begin(115200);

  // optional for ADC
  pinMode(POT_PIN, INPUT);

  // 50Hz is the standard servo refresh rate
  servo1.setPeriodHertz(50);
  servo2.setPeriodHertz(50);

  // SG90 typical pulse range
  servo1.attach(SERVO_PIN_1, 500, 2400);
  servo2.attach(SERVO_PIN_2, 500, 2400);
}

void loop() {
  anavalue = analogRead(POT_PIN);  // typically 0..4095 on ESP32 ADC
  anavalue = constrain(anavalue, 0, 4095);

  // Map Potentiometer value -> angles
  int angle1 = map(anavalue, 0, 2048, 0, 180);   // normal phase
  int angle2 = 180 - angle1;                     // opposite phase

  // Safety clamp for Potentiometer  
  angle1 = constrain(angle1, 0, 180);
  angle2 = constrain(angle2, 0, 180);

  // Drive two servo motors
  servo1.write(angle1);
  servo2.write(angle2);

  // Debug
  Serial.print("ADC=");
  Serial.print(anavalue);
  Serial.print("  angle1=");
  Serial.print(angle1);
  Serial.print("  angle2=");
  Serial.println(angle2);

  delay(20); // ~50Hz update
}