#define LED0_PIN PA1   // 外接 LED0
#define LED1_PIN PA4   // 外接 LED1
#define BEEP_PIN PA0   // 蜂鸣器
#define KEY0_PIN PB0   // 模拟按键0
#define KEY1_PIN PB1   // 模拟按键1
#define KEY2_PIN PB2   // 模拟按键2
#define KEY3_PIN PB3   // 模拟按键3

int beepState = LOW;   // 蜂鸣器状态
int led0State = HIGH;  // 初始点亮 LED0
int led1State = LOW;

void setup() {
  // 系统初始化阶段
  pinMode(LED0_PIN, OUTPUT);
  pinMode(LED1_PIN, OUTPUT);
  pinMode(BEEP_PIN, OUTPUT);

  pinMode(KEY0_PIN, INPUT_PULLUP);
  pinMode(KEY1_PIN, INPUT_PULLUP);
  pinMode(KEY2_PIN, INPUT_PULLUP);
  pinMode(KEY3_PIN, INPUT_PULLUP);

  // 初始状态
  digitalWrite(LED0_PIN, led0State);
  digitalWrite(LED1_PIN, led1State);
  digitalWrite(BEEP_PIN, beepState);
}

void loop() {
  int keyValue = getKeyValue();

  // --- 按流程逻辑执行 ---
  if (keyValue == 0) {
    delay(10); // 判断1
  }
  else if (keyValue == 3) {
    beepState = !beepState;
    digitalWrite(BEEP_PIN, beepState);
  }
  else if (keyValue == 2) {
    led1State = !led1State;
    digitalWrite(LED1_PIN, led1State);
  }
  else if (keyValue == 1) {
    led0State = !led0State;
    led1State = !led1State;
    digitalWrite(LED0_PIN, led0State);
    digitalWrite(LED1_PIN, led1State);
  }

  // 回到获取键值（循环）
  delay(50);
}

// 获取键值函数：返回1~3 或 0（默认）
int getKeyValue() {
  if (digitalRead(KEY0_PIN) == LOW) return 0;
  if (digitalRead(KEY1_PIN) == LOW) return 1;
  if (digitalRead(KEY2_PIN) == LOW) return 2;
  if (digitalRead(KEY3_PIN) == LOW) return 3;
  return -1; // 无按键按下
}