Node with DS18B20 and DHT22

[dbemowsk]

Just out of curiosity, why are you using DS18B20s with a DHT22? Are these all mounted on the same sensor board?

[dokho]

Hi!

It's to make a node for the 2nd floor of my house: 6 DS18B20 for bedrooms, office (?), stairs and 2 DHT22 for the 2 bathrooms.

DHT22 are more expensive than DS18B20 and i need to know humidity only for the bathrooms.

[dokho]

Hi!

I've try with developpement librairies and it's the same.

For information this is the sketch i'm using:

// Enable debug prints
#define MY_DEBUG

// Enable and select radio type attached 
#define MY_RADIO_NRF24
//#define MY_RADIO_RFM69
//#define MY_RS485
 
#include <SPI.h>
#include <MySensors.h>  
#include <DHT.h>
#include <DallasTemperature.h>
#include <OneWire.h>

#define MAX_ATTACHED_DS18B20 6

#define ONE_WIRE_BUS 4
#define DHT1_DATA_PIN 2
#define DHT2_DATA_PIN 3

#define CHILD_ID_DHT1HUM 6
#define CHILD_ID_DHT1TEMP 7
#define CHILD_ID_DHT2HUM 9
#define CHILD_ID_DHT2TEMP 8

#define SENSOR_TEMP_OFFSET 0

// Sleep time between sensor updates (in milliseconds)
// Must be >1000ms for DHT22 and >2000ms for DHT11
static const uint64_t UPDATE_INTERVAL = 3000;

unsigned long SLEEP_TIME = 30000;
bool metric = true;
bool receivedConfig = false;
int numSensors=0;

OneWire oneWire(ONE_WIRE_BUS); // Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
DallasTemperature sensors(&oneWire); // Pass the oneWire reference to Dallas Temperature. 

MyMessage msgDallas(0,V_TEMP);
MyMessage msgDHT1Temp(CHILD_ID_DHT1TEMP,V_TEMP);
MyMessage msgDHT1Hum(CHILD_ID_DHT1HUM,V_HUM);
MyMessage msgDHT2Hum(CHILD_ID_DHT2HUM,V_HUM);
MyMessage msgDHT2Temp(CHILD_ID_DHT2TEMP,V_TEMP);

DHT dht;

void before()
{
  // Startup up the OneWire library
  sensors.begin();
}
void setup()
{
// requestTemperatures() will not block current thread
  sensors.setWaitForConversion(false);  
}
void presentation()  
{ 
  // Send the sketch version information to the gateway
  sendSketchInfo("DualDHTandDallas", "1.1");

 // Fetch the number of attached temperature sensors  
  numSensors = sensors.getDeviceCount();

  // Present all sensors to controller
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
     present(i, S_TEMP);
  }
   
  present(CHILD_ID_DHT1TEMP,S_TEMP);
  present(CHILD_ID_DHT1HUM,S_HUM);
  present(CHILD_ID_DHT2HUM,S_HUM);
  present(CHILD_ID_DHT2TEMP,S_TEMP);
  
  
  metric = getConfig().isMetric;
}

void loop()      
{ 

// Fetch temperatures from Dallas sensors
  sensors.requestTemperatures();

  // query conversion time and sleep until conversion completed
  int16_t conversionTime = sensors.millisToWaitForConversion(sensors.getResolution());
  // sleep() call can be replaced by wait() call if node need to process incoming messages (or if node is repeater)
  sleep(conversionTime);

// Read temperatures and send them to controller 
  for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {
 
    // Fetch and round temperature to one decimal
    float temperature = static_cast<float>(static_cast<int>((getConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) / 10.;
 
  // Send in the new temperature
  send(msgDallas.setSensor(i).set(temperature,1));
      #ifdef MY_DEBUG
      Serial.print("Dallas");
      Serial.print(i);
      Serial.print(" :");
      Serial.println(temperature);
      #endif

//  sleep(SLEEP_TIME);
  }
   
  dht.setup(DHT1_DATA_PIN); // set data pin of DHT1 sensor
  if (UPDATE_INTERVAL <= dht.getMinimumSamplingPeriod()) {
    Serial.println("Warning: UPDATE_INTERVAL is smaller than supported by the sensor!");
  }
  // Sleep for the time of the minimum sampling period to give the sensor time to power up
  // (otherwise, timeout errors might occure for the first reading)
  sleep(dht.getMinimumSamplingPeriod());
  
  // Force reading sensor, so it works also after sleep()
  dht.readSensor(true);
  
  // Get temperature from DHT library
  float dht1temperature = dht.getTemperature();
  if (isnan(dht1temperature)) {
    Serial.println("Failed reading temperature from DHT!");
  } else 
    if (!metric) {
      dht1temperature = dht.toFahrenheit(dht1temperature);
    }
    
    dht1temperature += SENSOR_TEMP_OFFSET;
    send(msgDHT1Temp.set(dht1temperature, 1));

    #ifdef MY_DEBUG
    Serial.print("DHT1TEMP: ");
    Serial.println(dht1temperature);
    #endif
  sleep(UPDATE_INTERVAL);

  // Get humidity from DHT library
  float dht1humidity = dht.getHumidity();
  if (isnan(dht1humidity)) {
    Serial.println("Failed reading humidity from DHT");
  } 
  else {
   send(msgDHT1Hum.set(dht1humidity, 1));
    
    #ifdef MY_DEBUG
    Serial.print("DHT1HUM: ");
    Serial.println(dht1humidity);
    #endif
  } 

  // Sleep for a while to save energy
  sleep(UPDATE_INTERVAL); 


  dht.setup(DHT2_DATA_PIN); // set data pin of DHT2 sensor
  if (UPDATE_INTERVAL <= dht.getMinimumSamplingPeriod()) {
    Serial.println("Warning: UPDATE_INTERVAL is smaller than supported by the sensor!");
  }
  // Sleep for the time of the minimum sampling period to give the sensor time to power up
  // (otherwise, timeout errors might occure for the first reading)
  sleep(dht.getMinimumSamplingPeriod());
  
  // Force reading sensor, so it works also after sleep()
  dht.readSensor(true);
  
  // Get temperature from DHT library
  float dht2temperature = dht.getTemperature();
  if (isnan(dht2temperature)) {
    Serial.println("Failed reading temperature from DHT!");
  } else 
    if (!metric) {
      dht2temperature = dht.toFahrenheit(dht2temperature);
    }
    dht2temperature += SENSOR_TEMP_OFFSET;
    send(msgDHT2Temp.set(dht2temperature, 1));

    #ifdef MY_DEBUG
    Serial.print("DHT2TEMP: ");
    Serial.println(dht2temperature);
    #endif
  
sleep(UPDATE_INTERVAL);

  // Get humidity from DHT library
  float dht2humidity = dht.getHumidity();
  if (isnan(dht2humidity)) {
    Serial.println("Failed reading humidity from DHT");
  } else {
   send(msgDHT2Hum.set(dht2humidity, 1));
    
    #ifdef MY_DEBUG
    Serial.print("DHT2HUM: ");
    Serial.println(dht2humidity);
    #endif
  }

  sleep(UPDATE_INTERVAL); 

}

And in domoticz all childs have the same ID (#1)

Noboby have an idea of the problem ?

[EDIT]
And i just discover an other "problem": the 2nd DHT22 humidity value is updated with the value of the 1st one...

[dokho]

Up ... please :s

[hek]

Isn't the left column the sensor id? 0,1,6,7,8,9 ?

[dokho]

@hek
No it's the #1 in the "Values" column

On an other node with 4 DS18B20:

The DS18B20 have different ID (#1, #2, #3 and #4)

[hek]

I don't run Domoticz myself. But the numbers in the left column matches child ids in your sketch exactly.

[dbemowsk]

The numbers in the left column ARE the child IDs. The numbers next to V_TEMP in the values column are not the child IDs. Look at your Domoticz indexes and IDs for these under Setup > Devices.

[dokho]

Ok so the number next to V_TEMP in the values column are groupID ?

The problem in my DS18B20+DHT22 node is that they have all the same groupID, so domoticz group TEMP and HUM in the same device and the HUM of the 1st DHT22 is updated with the HUM of the 2nd one ...

[Jon Eng]

So I researched this a bit and here is the answer:

The grouping of devices origins from this commit:
https://github.com/domoticz/domoticz/pull/847

and the logic is:
https://github.com/domoticz/domoticz/issues/276

Unfortunately it doesn´t work very well with other sensor combinations that Temp/hum/pressure - like mine with voltage, impedance and so on..

I found a workaround by naming all sensors v_hum - then they are placed in different groups and are possible to work with in domoticz...