const int pinLED1=11,pinLED2=10,pinLED3=9;
const int pinBtn=2;    // Interrupt0
//
volatile int state=0,flag=1;
//
void setup(){
  pinMode(pinBtn,INPUT_PULLUP);
  attachInterrupt(0,ledControl,RISING);
  Serial.begin(9600); Serial.print("srart"); Serial.println(state);
}
//
void loop(){
  if(flag){ flag=0;
    Serial.print("cur state"); Serial.println(state);
    analogWrite(11,state); analogWrite(10,state); analogWrite(9,state);
  }
}
//
void ledControl(){
  if     (state>128)state=128;
  else if(state>  0)state=  0;
  else              state=255;
  flag=1;
}