_P034_DHT12.ino

//#######################################################################################################
//######################## Plugin 034: Temperature and Humidity sensor DHT 12 (I2C) #####################
//#######################################################################################################

#define PLUGIN_034
#define PLUGIN_ID_034         34
#define PLUGIN_NAME_034       "Temperature & Humidity - DHT12 (I2C)"
#define PLUGIN_VALUENAME1_034 "Temperature"
#define PLUGIN_VALUENAME2_034 "Humidity"

boolean Plugin_034_init = false;

#define DHT12_I2C_ADDRESS      0x5C // I2C address for the sensor

boolean Plugin_034(byte function, struct EventStruct *event, String& string)
{
  boolean success = false;

  switch (function)
  {
    case PLUGIN_DEVICE_ADD:
      {
        Device[++deviceCount].Number = PLUGIN_ID_034;
        Device[deviceCount].Type = DEVICE_TYPE_I2C;
        Device[deviceCount].VType = SENSOR_TYPE_TEMP_HUM;
        Device[deviceCount].Ports = 0;
        Device[deviceCount].PullUpOption = false;
        Device[deviceCount].InverseLogicOption = false;
        Device[deviceCount].FormulaOption = true;
        Device[deviceCount].ValueCount = 2;
        Device[deviceCount].SendDataOption = true;
        Device[deviceCount].TimerOption = true;
        Device[deviceCount].GlobalSyncOption = true;
        break;
      }

    case PLUGIN_GET_DEVICENAME:
      {
        string = F(PLUGIN_NAME_034);
        break;
      }

    case PLUGIN_GET_DEVICEVALUENAMES:
      {
        strcpy_P(ExtraTaskSettings.TaskDeviceValueNames[0], PSTR(PLUGIN_VALUENAME1_034));
        strcpy_P(ExtraTaskSettings.TaskDeviceValueNames[1], PSTR(PLUGIN_VALUENAME2_034));
        break;
      }

    case PLUGIN_READ:
      {
        byte dht_dat[5];
        byte dht_in;
        byte i;
        byte Retry = 0;
        boolean error = false;

        Wire.beginTransmission(DHT12_I2C_ADDRESS); // start transmission to device
        Wire.write(0); // sends register address to read from
        Wire.endTransmission(); // end transmission

        Wire.beginTransmission(DHT12_I2C_ADDRESS); // start transmission to device
        if (Wire.requestFrom(DHT12_I2C_ADDRESS, 5) == 5) { // send data n-bytes read
          for (i = 0; i < 5; i++)
          {
            dht_dat[i] = Wire.read(); // receive DATA
          }
        } else {
          error = true;
        }
        if (!error)
        {
          // Checksum calculation is a Rollover Checksum by design!
          byte dht_check_sum = dht_dat[0] + dht_dat[1] + dht_dat[2] + dht_dat[3]; // check check_sum

          if (dht_dat[4] == dht_check_sum)
          {
            float temperature = float(dht_dat[2]*10 + (dht_dat[3] & 0x7f)) / 10.0; // Temperature
            if (dht_dat[3] & 0x80) { temperature = -temperature; }
            float humidity = float(dht_dat[0]*10+dht_dat[1]) / 10.0; // Humidity

            UserVar[event->BaseVarIndex] = temperature;
            UserVar[event->BaseVarIndex + 1] = humidity;
            String log = F("DHT12: Temperature: ");
            log += UserVar[event->BaseVarIndex];
            addLog(LOG_LEVEL_INFO, log);
            log = F("DHT12: Humidity: ");
            log += UserVar[event->BaseVarIndex + 1];
            addLog(LOG_LEVEL_INFO, log);
/*
            log = F("DHT12: Data: ");
            for (int i=0; i < 5; i++)
            {
              log +=  dht_dat[i];
              log += ", ";
            }
            addLog(LOG_LEVEL_INFO, log);
*/
            success = true;
          } // checksum
        } // error
        if(!success)
        {
          String log = F("DHT12: No reading!");
          addLog(LOG_LEVEL_INFO, log);
          UserVar[event->BaseVarIndex] = NAN;
          UserVar[event->BaseVarIndex + 1] = NAN;
        }
        break;
      }
  }
  return success;
}