// Controlling multiple servo motors,
// by updating them every 10ms or 20ms.
//
// Version 1, July 25, 2021 by Koepel, Public Domain.
// Version 2, October 7, 2023 by Koepel, Public Domain.
//   Added pinMode() to setup() for the two buttons.

#include <Servo.h>

unsigned long previousMillis;
const unsigned long interval = 10;   // 10 or 20 milliseconds are common values

Servo servo2;

int count700ms = 0;    // count to 700ms for first servo motor

float r = 0.0;         // the angle for the sinus in radian for second servo motor

void setup() 
{
  servo2.attach(7);
}

void loop() 
{
  unsigned long currentMillis = millis();

  if( currentMillis - previousMillis >= interval)
  {
    previousMillis = currentMillis;

    // ------------------------------------------
    // Servo motor
    // A smooth sinus sweep
    // The speed is controlled by the first potentiometer
    // ------------------------------------------
    float s = sin( r);               // The sine from the angle in radian
    float t = (90.0 * s) + 90.0;     // convert -1...1 to 0...180
    int angle2 = int( t);            // convert it to integer for the servo angle
    servo2.write( angle2);

    int potentiometer1 = analogRead( A0);
    float r_increment = 0.001 + (0.00005 * float(potentiometer1));

    r += r_increment;
    if( r >= 2.0 * M_PI)
    {
      r -= 2.0 * M_PI;
    }
  }
}