// 直接用数字引脚D2（对应STM32的PA2，无映射坑）
#define DS18B20_PIN 2

// 单总线复位
uint8_t ds18b20_reset(void) {
  uint8_t presence;
  pinMode(DS18B20_PIN, OUTPUT);
  digitalWrite(DS18B20_PIN, LOW);
  delayMicroseconds(500);
  pinMode(DS18B20_PIN, INPUT);
  delayMicroseconds(70);
  presence = !digitalRead(DS18B20_PIN);
  delayMicroseconds(430);
  return presence;
}

// 写1位
void ds18b20_write_bit(uint8_t bit) {
  pinMode(DS18B20_PIN, OUTPUT);
  digitalWrite(DS18B20_PIN, LOW);
  delayMicroseconds(1);
  if (bit) {
    pinMode(DS18B20_PIN, INPUT);
  }
  delayMicroseconds(60);
  pinMode(DS18B20_PIN, INPUT);
  delayMicroseconds(1);
}

// 读1位
uint8_t ds18b20_read_bit(void) {
  uint8_t bit = 0;
  pinMode(DS18B20_PIN, OUTPUT);
  digitalWrite(DS18B20_PIN, LOW);
  delayMicroseconds(1);
  pinMode(DS18B20_PIN, INPUT);
  delayMicroseconds(15);
  bit = digitalRead(DS18B20_PIN);
  delayMicroseconds(45);
  return bit;
}

// 写1字节
void ds18b20_write_byte(uint8_t dat) {
  for (uint8_t i = 0; i < 8; i++) {
    ds18b20_write_bit(dat & 0x01);
    dat >>= 1;
  }
}

// 读1字节
uint8_t ds18b20_read_byte(void) {
  uint8_t dat = 0;
  for (uint8_t i = 0; i < 8; i++) {
    if (ds18b20_read_bit()) {
      dat |= (1 << i);
    }
  }
  return dat;
}

// 读取并转换温度
float ds18b20_read_temp(void) {
  uint8_t tempL, tempH;
  int16_t raw_temp;
  
  if (!ds18b20_reset()) {
    return -999.0f;
  }
  
  ds18b20_write_byte(0xCC);
  ds18b20_write_byte(0x44);
  delay(800);
  
  ds18b20_reset();
  ds18b20_write_byte(0xCC);
  ds18b20_write_byte(0xBE);
  
  tempL = ds18b20_read_byte();
  tempH = ds18b20_read_byte();
  
  raw_temp = (int16_t)((tempH << 8) | tempL);
  return raw_temp / 16.0f;
}

void setup() {
  Serial.begin(115200);
  Serial.println("DS18B20 启动成功");
}

void loop() {
  float temp = ds18b20_read_temp();
  
  Serial.print("当前温度: ");
  Serial.print(temp, 2);
  Serial.println(" °C");
  
  delay(1000);
}