const int up = 18;
const int down = 16;
const int led = 25;
double cnt = 0;
void setup() {
  Serial.begin(115200);
  pinMode(up, INPUT_PULLUP);
  pinMode(down, INPUT_PULLUP);
  pinMode(led, OUTPUT);
}
void loop() {
  int incr = !digitalRead(up);
  int decr = !digitalRead(down);
  switch (incr) {
    case 1:
      cnt++;
      break;
  }
  switch (decr) {
    case 1:
      cnt--;
      break;
  }
  if (cnt > 255) cnt = 255;
  if (cnt < 0 ) cnt = 0;
  analogWrite(led, cnt);
  Serial.print("Counter = ");
  Serial.println(cnt);
  delay(1000);
}