Smart gadget SHT4x を使って電子百葉箱を作る ③ Arduino MKR WiFi 1010

　マイコン・ボードArduino MKR WiFi 1010は、RF部にu-blox NINA-W102を搭載していて、Wi-FiとBLEが使えます。ボードは、秋月電子通商、スイッチサイエンスなどで購入できます。

　BLEはArduino BLEライブラリを使ってスケッチを記述します。古めのArduino MKR WiFi 1010のファームウェアは、新しくしておく必要があります。

●スケッチ

　Smart gadget SHT4xに接続し、温度と湿度を読み出す前回のスケッチのT_Characteristic_UUIDとH_Characteristic_UUIDが逆になっていたのを修正しました。


#include <ArduinoBLE.h>
#define localNAME "SHT40 Gadget"
#define T_Characteristic_UUID    "00002235-b38d-4985-720e-0f993a68ee41"
#define H_Characteristic_UUID    "00001235-b38d-4985-720e-0f993a68ee41"

void setup() {
  Serial.begin(115200);
  while (!Serial);
  BLE.begin();
  Serial.println("\n start BLE Central - Temperature/Humidity");
  // start scanning for peripherals
  BLE.scanForName(localNAME);
}

void loop() {
  // check if a peripheral has been discovered
  BLEDevice peripheral = BLE.available();

  if (peripheral) {
    // discovered a peripheral, print out address, local name, and advertised service
    Serial.print("Found ");
    Serial.print(peripheral.address());
    Serial.print(" '");
    Serial.print(peripheral.localName());
    Serial.print("' ");
    Serial.print(peripheral.advertisedServiceUuid());
    Serial.println();

    if (peripheral.localName() != localNAME) {
      return;
    }
    // stop scanning
    BLE.stopScan();

    readData(peripheral);

    // peripheral disconnected, start scanning again
    BLE.scanForName(localNAME);
  }
}

void readData(BLEDevice peripheral) {
  // connect to the peripheral
  Serial.print("\nConnecting ...");

  if (peripheral.connect()) {
    Serial.println("Connected");
  } else {
    Serial.println("Failed to connect!");
    return;
  }

  // discover peripheral attributes
  Serial.print("Discovering attributes ...");
  if (peripheral.discoverAttributes()) {
    Serial.println("Attributes discovered\n");
  } else {
    Serial.println("Attribute discovery failed!");
    peripheral.disconnect();
    return;
  }
  // retrieve the characteristic
  BLECharacteristic Temperature_Characteristic = peripheral.characteristic(T_Characteristic_UUID);
  BLECharacteristic Humidity_Characteristic  = peripheral.characteristic(H_Characteristic_UUID);

  if (!Temperature_Characteristic) {
    Serial.println("Peripheral does not have Temp characteristic!");
    peripheral.disconnect();
    return;
  } 

  Serial.println("---Found CHARACTERISTIC_UUID");
  while (peripheral.connected()) {
  if (Temperature_Characteristic.canRead()) {
    // read the characteristic value
    Temperature_Characteristic.read();
    if (Temperature_Characteristic.valueLength() > 0) {
      uint32_t  data = ((uint8_t)*(Temperature_Characteristic.value()+3) << 24) + ((uint8_t)*(Temperature_Characteristic.value()+2) << 16) + ((uint8_t)*(Temperature_Characteristic.value()+1) << 8)  +  ((uint8_t)*Temperature_Characteristic.value());
      int32_t f = pow(-1, int(bitRead(data,31)));
      double k =1 + ((((data<<1)<<8)>>9))/pow(2,23); 
      int32_t s = pow(2,((((data<<1)>>24))-127));
      Serial.print("\ntemp = ");
      Serial.println(f*k*s);

      Humidity_Characteristic.read();
      data = ((uint8_t)*(Humidity_Characteristic.value()+3) << 24) + ((uint8_t)*(Humidity_Characteristic.value()+2) << 16) + ((uint8_t)*(Humidity_Characteristic.value()+1) << 8)  +  ((uint8_t)*Humidity_Characteristic.value());
      f = pow(-1, int(bitRead(data,31)));
      k =1 + ((((data<<1)<<8)>>9))/pow(2,23); 
      s = pow(2,((((data<<1)>>24))-127));
      Serial.print("humi = ");
      Serial.println(f*k*s);
      delay(30000);
    }
  }
}
 
  Serial.println("Peripheral disconnected");
}

　シリアルモニタの様子です。