#include <Arduino.h>

const int analogOutPin = 9;
const int analogInPin = A0;

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

void loop() {
  // Generate a sine wave
  float frequency = 1000; // Hz
  float amplitude = 255;
  float time = millis() / 1000.0;
  float value = amplitude * sin(2 * PI * frequency * time);

  // Convert to analog voltage
  analogWrite(analogOutPin, (int)value);

  // Read and print the analog input
  int analogValue = analogRead(analogInPin);
  Serial.println(analogValue);

  delay(1);
}