Arduino Nano: LED brightness control with LDR

ldrLEDBrightness.ino

//Reference: https://www.instructables.com/id/Automatic-Lights-Using-LDR-Brightness-Control
int ledPin = 9;

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  int ldrValue = analogRead(A6); //with brightness, LDR resistance decreases, voltage increases at A6 which results in higher ldrValue. 5V = 1024 (10bit)
  int brightness = map(ldrValue, 100, 1000, 255, 0);
  Serial.print(ldrValue);
  Serial.print(", ");
  Serial.println(brightness);
  analogWrite(ledPin, brightness);
}