格安BLE温湿度計のデータをESP32で取得してみた

※自分用メモです。

最近話題のXiaomiの格安BLE温湿度計のデータをESP32で取得してみた。

試したのはXiaomiのLYWSD03MMCというやつ。
スマフォのアプリと接続すると、BLEのアドバタイズパケットにデータを載せて飛ばしてくるみたい。

以下ソースコード。

# include <BLEDevice.h>
# include <BLEUtils.h>
# include <BLEScan.h>
# include <BLEAdvertisedDevice.h>

int scanTime = 5; //In seconds
BLEScan* pBLEScan;

std::string strDeviceName = "LYWSD03MMC";

class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
    void putHex(uint8_t *ptr, size_t len) {
      for( size_t i=0; i<len; i++) {
        Serial.printf("%02X", *ptr++);  
      }
      Serial.println("");
    }
    void onResult(BLEAdvertisedDevice advertisedDevice) {

      int n = strDeviceName.compare(advertisedDevice.getName());
      if ( n == 0){ 
        uint8_t *pPayload = advertisedDevice.getPayload();
        size_t len = advertisedDevice.getPayloadLength();

        if ((*(pPayload + 0x03) == 0x0f) && (*(pPayload + 0x04) == 0x16) && (*(pPayload + 0x03) == 0x0f) && (*(pPayload + 0x05) == 0x95) && (*(pPayload + 0x06) == 0xfe)) {
          int16_t temp = *(pPayload + 18) + *(pPayload + 19) * 256;
          uint8_t humidity =  *(pPayload + 21);

          Serial.printf("Temp: %d Humidity:%d\n", temp, humidity);
        }
      }
    }
};

void setup() {
  Serial.begin(115200);
  Serial.println("Scanning...");

  BLEDevice::init("");
  pBLEScan = BLEDevice::getScan(); //create new scan
  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
  pBLEScan->setActiveScan(true); //active scan uses more power, but get results faster
  pBLEScan->setInterval(100);
  pBLEScan->setWindow(99);  // less or equal setInterval value
}

void loop() {
  // put your main code here, to run repeatedly:
  BLEScanResults foundDevices = pBLEScan->start(scanTime, false);
  Serial.print("Devices found: ");
  Serial.println(foundDevices.getCount());
  Serial.println("Scan done!");
  pBLEScan->clearResults();   // delete results fromBLEScan buffer to release memory
  delay(2000);
}

結構簡単。