int keyPins[] = {2, 3, 4, 5, 6, 7, 8, 9};
int tones[] = {262, 294, 330, 349, 392, 440, 494, 523};
int keyNum = 8;
#define BUZZER_PIN 10
#define LED_PIN 13
// 一位共阳数码管引脚定义
#define a  A0
#define b  A1
#define c  A2
#define d  A3
#define e  A4
#define f  A5
#define g  11
// 共阴极段码表（代码里取反适配共阳）
byte numCode[9] = {
  B1111110, // 0
  B0110000, // 1
  B1101101, // 2
  B1111001, // 3
  B0110011, // 4
  B1011011, // 5
  B1011111, // 6
  B1110000, // 7
  B1111111  // 8
};
// 适配共阳极的显示函数
void displayNum(int n){
  if(n < 0 || n > 8) n = 0;
  byte code = numCode[n];
  digitalWrite(a, !bitRead(code,6));
  digitalWrite(b, !bitRead(code,5));
  digitalWrite(c, !bitRead(code,4));
  digitalWrite(d, !bitRead(code,3));
  digitalWrite(e, !bitRead(code,2));
  digitalWrite(f, !bitRead(code,1));
  digitalWrite(g, !bitRead(code,0));
}
void setup() {
  // 原有按键初始化不变
  for (int i = 0; i < keyNum; i++) {
    pinMode(keyPins[i], INPUT_PULLUP);
  }
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  Serial.begin(9600);
  // 数码管段脚设输出
  pinMode(a, OUTPUT);
  pinMode(b, OUTPUT);
  pinMode(c, OUTPUT);
  pinMode(d, OUTPUT);
  pinMode(e, OUTPUT);
  pinMode(f, OUTPUT);
  pinMode(g, OUTPUT);
  displayNum(0); // 上电显示0
  Serial.println("八音电子琴启动完成");
}
void loop() {
  for (int i = 0; i < keyNum; i++) {
    if (digitalRead(keyPins[i]) == LOW) {
      tone(BUZZER_PIN, tones[i]);
      digitalWrite(LED_PIN, HIGH);
      displayNum(i+1); // 按下显示对应数字
      Serial.print("按键：");
      Serial.println(i+1);
      delay(20);
      while (digitalRead(keyPins[i]) == LOW) {
        delay(10);
      }
      noTone(BUZZER_PIN);
      digitalWrite(LED_PIN, LOW);
      displayNum(0); // 松开回到0
    }
  }
  delay(10);
}