#define BUZZZER_PIN A2
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, STM32!");
  pinMode(A2, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  if(Serial.available()){
    char c= Serial.read();
    if(c == 'b'){
      Serial.println("Buzzer đang kêu");
      tone(A2, 1000);
      delay(2200);
      noTone(A2);
      Serial.println("Buzzer dừng lại");
    }
    else if(c != '\n' && c != '\r'){
      Serial.print("Lỗi: không hiểu ký tự ");
      Serial.println();
    }
  }
}