int redPin = 9;
int bluePin = 10;
int val;

void setup()
{
  // put your setup code here, to run once:
    pinMode(redPin,OUTPUT);
    pinMode(bluePin,OUTPUT);
}
void loop()
{
  // put your main code here, to run repeatedly:
    for(val=0;val<256;val++)
    {
        analogWrite(redPin,val);
        analogWrite(bluePin,255-val);
        delay(5);
    }
   
    for(val=0;val<256;val++)
    {
        analogWrite(redPin,255-val);
        analogWrite(bluePin,val);
        delay(5);
    }

}