const byte ledPin = 9;
const byte LDR = 5;   // A5
int val = 0;
int ogr = 0;

const byte LDR2 = 0;  // A0
int val2 = 0;

const byte buzzPin = 10;
const byte buzzPin2 = 12;

int maxVal = 0;

void setup() {
  Serial.begin(9600);
  pinMode(buzzPin, OUTPUT);
  pinMode(buzzPin2, OUTPUT);
  // пин 9 — ШИМ, настройка не нужна
}

void loop() {
  if (Serial.available() > 0) {
    maxVal = Serial.read();
    if ((maxVal > 47) && (maxVal < 58)) {
      maxVal = maxVal - 48;
      ogr = maxVal;
      Serial.print("max = ");
      Serial.println(maxVal, DEC);
    }
  }

  val = analogRead(LDR);
  int brightness = val / 4 - ogr * 20;
  if (brightness < 0) brightness = 0;
  if (brightness > 255) brightness = 255;
  analogWrite(ledPin, brightness);

  Serial.print(val);
  Serial.print(", ogr=");
  Serial.print(ogr);
  Serial.print(", ");

  val2 = analogRead(LDR2);
  Serial.println(val2);

  tone(buzzPin, val);
  tone(buzzPin2, val2);
  delay(100);
}