#define Switch_in   2       // Entrée du switch 
#define PWM_out     9       // Sortie PWM
#define N           300     // A faire varié en fonction de la pente 
#define Pas_us      10      // Pas en µS 


int valSwitch=0;            // 0-1

void setup() 
{
  pinMode(Switch_in, INPUT);
  pinMode(PWM_out, OUTPUT);
  digitalWrite(PWM_out, LOW);
}

void loop() 
{
  
  // Lecture du switch 
  while((valSwitch=digitalRead(Switch_in))==0);


  // Génération de la rampe 
  while(valSwitch==1)
  {
    
    // Montée
    for(int n=0;n<N;n++)
    {
        digitalWrite(PWM_out, HIGH); delayMicroseconds(n*Pas_us);  
        digitalWrite(PWM_out, LOW);  delayMicroseconds((N-n)*Pas_us); 
    }

    // Descente
    for(int n=N;n>0;n--)
    {
        digitalWrite(PWM_out, HIGH); delayMicroseconds(n*Pas_us);  
        digitalWrite(PWM_out, LOW);  delayMicroseconds((N-n)*Pas_us); 
    }

    digitalWrite(PWM_out, LOW);
    while((valSwitch=digitalRead(Switch_in))!=0);
    delay(2000); 
  }
}