// MCU BASIC: https://www.basic4mcu.com
// DateTime : 2019-04-16 오전 9:56:12
// by Ok-Hyun Park
//
int sw1_in=digitalRead(sw1);
if(sw1_in){ // 스위치를 누르면
  for(int val=0; val<=255; val++){ analogWrite(9,val); delay(10); } // 점차 밝아지다가  
  for(int val=0; val<=255; val--){ analogWrite(9,val); delay(10); } // 점차 어두워짐
}