_P005_DHT.ino

//#######################################################################################################
//######################## Plugin 006: Temperature and Humidity sensor DHT 11/22 ########################
//#######################################################################################################

#define PLUGIN_005
#define PLUGIN_ID_005         5
#define PLUGIN_NAME_005       "Temp + Hum DHT"
#define PLUGIN_VALUENAME1_005 "Temperature"
#define PLUGIN_VALUENAME2_005 "Humidity"

uint8_t Plugin_005_DHT_Pin;

boolean Plugin_005(byte function, struct EventStruct *event, String& string)
{
  boolean success = false;
  
  switch (function)
  {
    case PLUGIN_DEVICE_ADD:
      {
        Device[++deviceCount].Number = PLUGIN_ID_005;
        Device[deviceCount].Type = DEVICE_TYPE_SINGLE;
        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;
        break;
      }

    case PLUGIN_GET_DEVICENAME:
      {
        string = F(PLUGIN_NAME_005);
        break;
      }

    case PLUGIN_GET_DEVICEVALUENAMES:
      {
        strcpy_P(ExtraTaskSettings.TaskDeviceValueNames[0], PSTR(PLUGIN_VALUENAME1_005));
        strcpy_P(ExtraTaskSettings.TaskDeviceValueNames[1], PSTR(PLUGIN_VALUENAME2_005));
        break;
      }

    case PLUGIN_WEBFORM_LOAD:
      {
        byte choice = Settings.TaskDevicePluginConfig[event->TaskIndex][0];
        String options[2];
        options[0] = F("DHT 11");
        options[1] = F("DHT 22");
        int optionValues[2];
        optionValues[0] = 11;
        optionValues[1] = 22;
        string += F("<TR><TD>DHT Type:<TD><select name='plugin_005_dhttype'>");
        for (byte x = 0; x < 2; x++)
        {
          string += F("<option value='");
          string += optionValues[x];
          string += "'";
          if (choice == optionValues[x])
            string += F(" selected");
          string += ">";
          string += options[x];
          string += F("</option>");
        }
        string += F("</select>");

        success = true;
        break;
      }

    case PLUGIN_WEBFORM_SAVE:
      {
        String plugin1 = WebServer.arg("plugin_005_dhttype");
        Settings.TaskDevicePluginConfig[event->TaskIndex][0] = plugin1.toInt();
        success = true;
        break;
      }

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

        byte Par3 = Settings.TaskDevicePluginConfig[event->TaskIndex][0];

        Plugin_005_DHT_Pin = Settings.TaskDevicePin1[event->TaskIndex];

        do
        {
          pinMode(Plugin_005_DHT_Pin, OUTPUT);
          // DHT start condition, pull-down i/o pin for 18ms
          digitalWrite(Plugin_005_DHT_Pin, LOW);              // Pull low
          delay(18);
          digitalWrite(Plugin_005_DHT_Pin, HIGH);             // Pull high
          delayMicroseconds(40);
          pinMode(Plugin_005_DHT_Pin, INPUT);                 // change pin to input
          //delayMicroseconds(40);

          dht_in = digitalRead(Plugin_005_DHT_Pin);
          if (!dht_in)
          {
            delayMicroseconds(80);
            dht_in = digitalRead(Plugin_005_DHT_Pin);
            if (dht_in)
            {
              delayMicroseconds(40);                     // now ready for data reception
              for (i = 0; i < 5; i++)
              {
                byte data = Plugin_005_read_dht_dat();
                if (data != -1)
                  dht_dat[i] = data;
                else
                {
                  addLog(LOG_LEVEL_ERROR, (char*)"DHT  : protocol timeout!");
                  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)
                {

                  if (Par3 == 11)
                  {
                    UserVar[event->BaseVarIndex] = float(dht_dat[2]); // Temperature
                    UserVar[event->BaseVarIndex + 1] = float(dht_dat[0]); // Humidity
                  }

                  if (Par3 == 22)
                  {
                    if (dht_dat[2] & 0x80) // negative temperature
                      UserVar[event->BaseVarIndex] = -0.1 * word(dht_dat[2] & 0x7F, dht_dat[3]);
                    else
                      UserVar[event->BaseVarIndex] = 0.1 * word(dht_dat[2], dht_dat[3]);
                    UserVar[event->BaseVarIndex + 1] = word(dht_dat[0], dht_dat[1]) * 0.1; // Humidity
                  }
                  Serial.print(F("DHT  : Temperature: "));
                  Serial.println(UserVar[event->BaseVarIndex]);
                  Serial.print(F("DHT  : Humidity: "));
                  Serial.println(UserVar[event->BaseVarIndex + 1]);
                  success = true;
                } // checksum

              } // error
            } // dht
          }  // !dht
          if (!success)
          {
            delay(2000);
          }
        } while (!success && ++Retry < 3);
        break;
      }
  }
  return success;
}


/*********************************************************************************************\
* DHT sub to get an 8 bit value from the receiving bitstream
\*********************************************************************************************/
int Plugin_005_read_dht_dat(void)
{
  byte i = 0;
  byte result = 0;
  byte counter = 0;
  noInterrupts();
  for (i = 0; i < 8; i++)
  {
    while ((!digitalRead(Plugin_005_DHT_Pin)) && (counter < 100))
    {
      delayMicroseconds(1);
      counter++;
    }
    if (counter >= 100)
    {
      interrupts();
      return -1;
    }
    delayMicroseconds(30);
    if (digitalRead(Plugin_005_DHT_Pin))
      result |= (1 << (7 - i));
    counter = 0;
    while ((digitalRead(Plugin_005_DHT_Pin)) && (counter < 100))
    {
      delayMicroseconds(1);
      counter++;
    }
    if (counter >= 100)
    {
      interrupts();
      return -1;
    }
  }
  interrupts();
  return result;
}