const int ledPin1 = 2;
const int ledPin2 = 4;
void setup() {
  // put your setup code here, to run once:
  ledcAttachChannel(ledPin1, 5000, 8,0);
  ledcAttachChannel(ledPin2, 5000, 8,1);
}

void loop() {
  // put your main code here, to run repeatedly:
  for (int i = 0; i <= 255; i++) {
    ledcWrite(ledPin1,i);
    ledcWrite(ledPin2,255-i);
    delay(2);
  }
  for (int i = 255; i >= 0; i--) {
    ledcWriteChannel(0,i);
    ledcWriteChannel(1,255-i);
    delay(2);
  }
}