DHT22 verify issue.



  • Using the raw code from the Mysensors example I'm getting errors trying to verify the code.

    Haven't changed a single bit of the raw code.

    /**
     * The MySensors Arduino library handles the wireless radio link and protocol
     * between your home built sensors/actuators and HA controller of choice.
     * The sensors forms a self healing radio network with optional repeaters. Each
     * repeater and gateway builds a routing tables in EEPROM which keeps track of the
     * network topology allowing messages to be routed to nodes.
     *
     * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
     * Copyright (C) 2013-2015 Sensnology AB
     * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
     *
     * Documentation: http://www.mysensors.org
     * Support Forum: http://forum.mysensors.org
     *
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * version 2 as published by the Free Software Foundation.
     *
     *******************************
     *
     * REVISION HISTORY
     * Version 1.0: Henrik EKblad
     * Version 1.1 - 2016-07-20: Converted to MySensors v2.0 and added various improvements - Torben Woltjen (mozzbozz)
     * 
     * DESCRIPTION
     * This sketch provides an example of how to implement a humidity/temperature
     * sensor using a DHT11/DHT-22.
     *  
     * For more information, please visit:
     * http://www.mysensors.org/build/humidity
     * 
     */
    
    // 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>
    
    // Set this to the pin you connected the DHT's data pin to
    #define DHT_DATA_PIN 3
    
    // Set this offset if the sensor has a permanent small offset to the real temperatures
    #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 = 60000;
    
    // Force sending an update of the temperature after n sensor reads, so a controller showing the
    // timestamp of the last update doesn't show something like 3 hours in the unlikely case, that
    // the value didn't change since;
    // i.e. the sensor would force sending an update every UPDATE_INTERVAL*FORCE_UPDATE_N_READS [ms]
    static const uint8_t FORCE_UPDATE_N_READS = 10;
    
    #define CHILD_ID_HUM 0
    #define CHILD_ID_TEMP 1
    
    float lastTemp;
    float lastHum;
    uint8_t nNoUpdatesTemp;
    uint8_t nNoUpdatesHum;
    bool metric = true;
    
    MyMessage msgHum(CHILD_ID_HUM, V_HUM);
    MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
    DHT dht;
    
    
    void presentation()  
    { 
      // Send the sketch version information to the gateway
      sendSketchInfo("TemperatureAndHumidity", "1.1");
      
      // Register all sensors to gw (they will be created as child devices)
      present(CHILD_ID_HUM, S_HUM);
      present(CHILD_ID_TEMP, S_TEMP);
      
      metric = getControllerConfig().isMetric;
    }
    
    
    void setup()
    {
      dht.setup(DHT_DATA_PIN); // set data pin of DHT 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());
    }
    
    
    void loop()      
    {  
      // Force reading sensor, so it works also after sleep()
      dht.readSensor(true);
      
      // Get temperature from DHT library
      float temperature = dht.getTemperature();
      if (isnan(temperature)) {
        Serial.println("Failed reading temperature from DHT!");
      } else if (temperature != lastTemp || nNoUpdatesTemp == FORCE_UPDATE_N_READS) {
        // Only send temperature if it changed since the last measurement or if we didn't send an update for n times
        lastTemp = temperature;
        if (!metric) {
          temperature = dht.toFahrenheit(temperature);
        }
        // Reset no updates counter
        nNoUpdatesTemp = 0;
        temperature += SENSOR_TEMP_OFFSET;
        send(msgTemp.set(temperature, 1));
    
        #ifdef MY_DEBUG
        Serial.print("T: ");
        Serial.println(temperature);
        #endif
      } else {
        // Increase no update counter if the temperature stayed the same
        nNoUpdatesTemp++;
      }
    
      // Get humidity from DHT library
      float humidity = dht.getHumidity();
      if (isnan(humidity)) {
        Serial.println("Failed reading humidity from DHT");
      } else if (humidity != lastHum || nNoUpdatesHum == FORCE_UPDATE_N_READS) {
        // Only send humidity if it changed since the last measurement or if we didn't send an update for n times
        lastHum = humidity;
        // Reset no updates counter
        nNoUpdatesHum = 0;
        send(msgHum.set(humidity, 1));
        
        #ifdef MY_DEBUG
        Serial.print("H: ");
        Serial.println(humidity);
        #endif
      } else {
        // Increase no update counter if the humidity stayed the same
        nNoUpdatesHum++;
      }
    
      // Sleep for a while to save energy
      sleep(UPDATE_INTERVAL); 
    }
    
    

    Getting the following errors

    sketch_mar01a:73: error: no matching function for call to 'DHT::DHT()'
    DHT dht;

    Any help recommended?

    Thanks


  • Mod



  • I have the DHT sensor library installed under recommended libraries and can run the DHTtester code no problems.
    I have uploaded the sketch to my nodemcu and its working fine and can see the results via serial monitor

    as shown here

    #include <DHT.h>
    #include <DHT_U.h>
    
    // Example testing sketch for various DHT humidity/temperature sensors
    // Written by ladyada, public domain
    
    #include "DHT.h"
    
    #define DHTPIN 2     // what digital pin we're connected to
    
    // Uncomment whatever type you're using!
    //#define DHTTYPE DHT11   // DHT 11
    #define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
    //#define DHTTYPE DHT21   // DHT 21 (AM2301)
    
    // Connect pin 1 (on the left) of the sensor to +5V
    // NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
    // to 3.3V instead of 5V!
    // Connect pin 2 of the sensor to whatever your DHTPIN is
    // Connect pin 4 (on the right) of the sensor to GROUND
    // Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
    
    // Initialize DHT sensor.
    // Note that older versions of this library took an optional third parameter to
    // tweak the timings for faster processors.  This parameter is no longer needed
    // as the current DHT reading algorithm adjusts itself to work on faster procs.
    DHT dht(DHTPIN, DHTTYPE);
    
    void setup() {
      Serial.begin(9600);
      Serial.println("DHTxx test!");
    
      dht.begin();
    }
    
    void loop() {
      // Wait a few seconds between measurements.
      delay(2000);
    
      // Reading temperature or humidity takes about 250 milliseconds!
      // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
      float h = dht.readHumidity();
      // Read temperature as Celsius (the default)
      float t = dht.readTemperature();
      // Read temperature as Fahrenheit (isFahrenheit = true)
      float f = dht.readTemperature(true);
    
      // Check if any reads failed and exit early (to try again).
      if (isnan(h) || isnan(t) || isnan(f)) {
        Serial.println("Failed to read from DHT sensor!");
        return;
      }
    
      // Compute heat index in Fahrenheit (the default)
      float hif = dht.computeHeatIndex(f, h);
      // Compute heat index in Celsius (isFahreheit = false)
      float hic = dht.computeHeatIndex(t, h, false);
    
      Serial.print("Humidity: ");
      Serial.print(h);
      Serial.print(" %\t");
      Serial.print("Temperature: ");
      Serial.print(t);
      Serial.print(" *C ");
      Serial.print(f);
      Serial.print(" *F\t");
      Serial.print("Heat index: ");
      Serial.print(hic);
      Serial.print(" *C ");
      Serial.print(hif);
      Serial.println(" *F");
    }
    

    Ill have a read through your recommended threads to see what else I can troubleshoot.
    I also tried looking at others projects and examples but didn't see much code



  • seems to be fixed after I deleted and reinstalled the DHT library several time.

    Thanks mfalkvidd



  • Ok so I got it all working, somewhat.

    Im running a NodeMCU with wifi to MQTT with the below sketch. (note removed the header of the code to protect private info, I have had the MQTT/ESP part working fine with other sensors/actuators)

    
    
    #include <ESP8266WiFi.h>
    #include <MySensors.h>
    
    // DHT22
    #include <DHT.h>
    
    // Set this to the pin you connected the DHT's data pin to
    #define DHT_DATA_PIN 4
    
    // Set this offset if the sensor has a permanent small offset to the real temperatures
    #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 = 60000;
    
    // Force sending an update of the temperature after n sensor reads, so a controller showing the
    // timestamp of the last update doesn't show something like 3 hours in the unlikely case, that
    // the value didn't change since;
    // i.e. the sensor would force sending an update every UPDATE_INTERVAL*FORCE_UPDATE_N_READS [ms]
    static const uint8_t FORCE_UPDATE_N_READS = 10;
    
    #define CHILD_ID_HUM 0
    #define CHILD_ID_TEMP 1
    
    float lastTemp;
    float lastHum;
    uint8_t nNoUpdatesTemp;
    uint8_t nNoUpdatesHum;
    bool metric = true;
    
    MyMessage msgHum(CHILD_ID_HUM, V_HUM);
    MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
    DHT dht;
    
    
    void presentation()  
    { 
      // Send the sketch version information to the gateway
      sendSketchInfo("TemperatureAndHumidity", "1.1");
      
      // Register all sensors to gw (they will be created as child devices)
      present(CHILD_ID_HUM, S_HUM);
      present(CHILD_ID_TEMP, S_TEMP);
      
      metric = getControllerConfig().isMetric;
    }
    
    void setup()
    {
      dht.setup(DHT_DATA_PIN); // set data pin of DHT 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());
    }
    
    
    void loop()      
    {  
      // Force reading sensor, so it works also after sleep()
      dht.readSensor(true);
      
      // Get temperature from DHT library
      float temperature = dht.getTemperature();
      if (isnan(temperature)) {
        Serial.println("Failed reading temperature from DHT!");
      } else if (temperature != lastTemp || nNoUpdatesTemp == FORCE_UPDATE_N_READS) {
        // Only send temperature if it changed since the last measurement or if we didn't send an update for n times
        lastTemp = temperature;
        if (!metric) {
          temperature = dht.toFahrenheit(temperature);
        }
        // Reset no updates counter
        nNoUpdatesTemp = 0;
        temperature += SENSOR_TEMP_OFFSET;
        send(msgTemp.set(temperature, 1));
    
        #ifdef MY_DEBUG
        Serial.print("T: ");
        Serial.println(temperature);
        #endif
      } else {
        // Increase no update counter if the temperature stayed the same
        nNoUpdatesTemp++;
      }
    
      // Get humidity from DHT library
      float humidity = dht.getHumidity();
      if (isnan(humidity)) {
        Serial.println("Failed reading humidity from DHT");
      } else if (humidity != lastHum || nNoUpdatesHum == FORCE_UPDATE_N_READS) {
        // Only send humidity if it changed since the last measurement or if we didn't send an update for n times
        lastHum = humidity;
        // Reset no updates counter
        nNoUpdatesHum = 0;
        send(msgHum.set(humidity, 1));
        
        #ifdef MY_DEBUG
        Serial.print("H: ");
        Serial.println(humidity);
        #endif
      } else {
        // Increase no update counter if the humidity stayed the same
        nNoUpdatesHum++;
      }
    
      // Sleep for a while to save energy
      sleep(UPDATE_INTERVAL); 
    }
    

    Basically a copy paste of what on the mysensors page, however this code fails reading the DHT22/am2302 sensor Im using.

    If I use the DHT_Test code supplied with the mysensors master library, everything works fine, same pin, not even re powering the device, flashed it many times, and I'm stuck.

    #include "DHT.h"
    
    DHT dht;
    
    void setup()
    {
      Serial.begin(9600);
      Serial.println();
      Serial.println("Status\tHumidity (%)\tTemperature (C)\t(F)");
    
      dht.setup(2); // data pin 2
    }
    
    void loop()
    {
      delay(dht.getMinimumSamplingPeriod());
    
      float humidity = dht.getHumidity();
      float temperature = dht.getTemperature();
    
      Serial.print(dht.getStatusString());
      Serial.print("\t");
      Serial.print(humidity, 1);
      Serial.print("\t\t");
      Serial.print(temperature, 1);
      Serial.print("\t\t");
      Serial.println(dht.toFahrenheit(temperature), 1);
    }
    

  • Mod

    @Bryden when the reading fails, what is the result? No reading at all? Incorrect temperature?



  • Its serial printing "Failed reading temperature from DHT" and "Failed reading humidity from DHT" as per the void loop in the sketch.

    I can run DHT_Test, and it works fine, serial printing OK 1.0 25.8 47.3 (or what ever the temp and humidity is) then immediately upload the mysensor sketch and get the failed reading returns.


  • Hero Member

    @Bryden try to replace sleep() with wait(). I cannot get sleep to work well on an esp8266.



  • @AWI said in DHT22 verify issue.:

    @Bryden try to replace sleep() with wait(). I cannot get sleep to work well on an esp8266.

    Well @AWI thats just weird, Its working now, I'm not much of a programmer, But something as little as changing a sleep command to wait fixed the issue is weird as hell.

    Have you got any explanation or should I just blame the angry pixies getting in a huff.

    You have well earned your hero member status.


  • Mod

    @Bryden on ESP8266, the MySensors sleep function always returns immediately. That causes the code to try to read data from the sensor too soon.

    From what I understand, the reason that sleep doesn't sleep on ESP8266 is that the ESP8266 requires a full reboot when it wakes up from sleep, which usually isn't what people want when calling sleep.

    But people don't want immediate return either. I don't know what reasoning was behind designing the MySensors sleep function on ESP8266 but i assume there was a compelling reason to let sleep() return immediately.

    Maybe a more logical choice would be to let sleep() on ESP8266 do what wait() does?



  • I suppose I could remove the sleep / wait function all together seems as it's going to run off mains and not a battery, which is what I would assume people wanted a sleep function for altogether.


  • Hero Member

    @Bryden The wait() function is a MySensors replacement of the standard delay() in c++. The "added value" here is that wait() lets you listen to incoming messages while doing nothing. Unless you want some activity during waiting for a next reading (like blinking a led or so) I think wait() is rather usefull ;-)


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