#include <Arduino.h>

#define led 26
#define feq 2000
#define resolution 8
#define channel 0
void setup() {
  //ledcSetup(channel,feq,resolution);
  ledcAttach(led,feq,resolution);
}

void loop() {
  for(int i = 0;i<pow(2,resolution);i++){
    ledcWrite(channel,i);
    delay(10);
  }
   for(int i = pow(2,resolution)-1;i>0;i--){
    ledcWrite(channel,i);
    delay(10);
  }
 
}