A beginners question



  • I have put a DHT22 sensor to my serial gateway, and in the sketch code for the DHT22 sensor there is sleeping “code”, static const uint64_t UPDATE_INTERVAL = 60000; and on the end sleep(UPDATE_INTERVAL); . Will this affect the gateway forcing it to sleep or will this only affect the DHT sensor? My sketch:

    // Enable debug prints to serial monitor
    #define MY_DEBUG 
    
    
    // Enable and select radio type attached
    #define MY_RADIO_NRF24
    //#define MY_RADIO_RFM69
    
    // Set LOW transmit power level as default, if you have an amplified NRF-module and
    // power your radio separately with a good regulator you can turn up PA level. 
    #define MY_RF24_PA_LEVEL RF24_PA_LOW
    
    // Enable serial gateway
    #define MY_GATEWAY_SERIAL
    
    // Define a lower baud rate for Arduino's running on 8 MHz (Arduino Pro Mini 3.3V & SenseBender)
    #if F_CPU == 8000000L
    #define MY_BAUD_RATE 38400
    #endif
    
    // Flash leds on rx/tx/err
    #define MY_LEDS_BLINKING_FEATURE
    // Set blinking period
    #define MY_DEFAULT_LED_BLINK_PERIOD 300
    
    // Inverses the behavior of leds
    //#define MY_WITH_LEDS_BLINKING_INVERSE
    
    // Enable inclusion mode
    #define MY_INCLUSION_MODE_FEATURE
    // Enable Inclusion mode button on gateway
    #define MY_INCLUSION_BUTTON_FEATURE
    
    // Inverses behavior of inclusion button (if using external pullup)
    //#define MY_INCLUSION_BUTTON_EXTERNAL_PULLUP
    
    // Set inclusion mode duration (in seconds)
    #define MY_INCLUSION_MODE_DURATION 60 
    // Digital pin used for inclusion mode button
    #define MY_INCLUSION_MODE_BUTTON_PIN  3 
    
    // Uncomment to override default HW configurations
    //#define MY_DEFAULT_ERR_LED_PIN 4  // Error led pin
    //#define MY_DEFAULT_RX_LED_PIN  6  // Receive led pin
    //#define MY_DEFAULT_TX_LED_PIN  5  // the PCB, on board LED
    
    #include <DHT.h>
    #include <SPI.h>
    #include <MySensors.h>  
    
    //DHT Begin
    
    // Set this to the pin you connected the DHT's data pin to
    #define DHT_DATA_PIN 8
    
    // 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 10
    #define CHILD_ID_TEMP 11
    
    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 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 presentation()  
    { 
      // Send the sketch version information to the gateway
      sendSketchInfo("Getway+DHT", "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 = getConfig().isMetric;
    }
    
    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); 
    }
    

  • Contest Winner

    @Hilltan If you use sleep, an Arduino will go to sleep and is not able to receive any message. By using this

    sleep(UPDATE_INTERVAL);
    

    Your gateway will go to sleep and will not receive messages from other nodes. Which is kind of the main task of a gateway.

    It should be

    wait( UPDATE_INTERVAL );
    

    Basic rule is. Use sleep only on battery powered nodes that don't have any incoming message. Use wait in all other circumstances.

    ps. I put your sketch between 4 `



  • Thanks for a replay. I change sleep to wait then. What I was concerned about was to “read” to often from the DHT sensor. But I believe "static const uint64_t UPDATE_INTERVAL = 60000; " in the beginning will regulate this, so my gateway will not over read the DHT sensor?


  • Mod

    @Hilltan the wait call will not return until the specified number of milliseconds has passed. So yes it will prevent from reading the dht too often.



  • About to built a dht / pir / repeater.
    Since i cant Sleep it do i need to change all sleep with wait?

    In the dht example there is a Sleep to let the sensor settle before Reading. Should this be a wait instead then?


  • Mod



  • @mfalkvidd

    Hmm i have a combined sketch of the pir and dht example that works fine on a node that Can Sleep for a bit and interrupt with change on the pir.

    But if i take that sketch and change the Sleep with interrupt to a wait(sleep_time) the pir is not registrering movement between wait Times'.

    FIf i remove the wait alltoghter the pir is reporting the status every ms instead with the result that the dht can't read the temp!


  • Mod

    @meanmrgreen could you post your sketch?



  • this is it.

    https://create.arduino.cc/editor/meanmrgreen/e7e0219e-139a-4e89-88da-e02f0864e9c6/preview

    not sure of link worksge. on phone atm. will paste it from comp later if its not working.



  • /**
     * 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
     * 
     * DESCRIPTION
     * Motion Sensor example using HC-SR501 
     * http://www.mysensors.org/build/motion
     *
     */
    //Enable Repeater
    #define MY_REPEATER_FEATURE
    
    // Enable debug prints
    #define MY_DEBUG
    
    // Enable and select radio type attached
    #define MY_RADIO_NRF24
    //#define MY_RADIO_RFM69
    
    #include <SPI.h>
    #include <MySensors.h>
    #include <DHT.h>
    
    unsigned long SLEEP_TIME = 120000; // Sleep time between reports (in milliseconds)
    #define DIGITAL_INPUT_SENSOR 2   // The digital input you attached your motion sensor.  (Only 2 and 3 generates interrupt!)
    #define DHT_DATA_PIN 4
    #define CHILD_ID_MOT 1   // Id of the sensor child
    #define CHILD_ID_HUM 0
    #define CHILD_ID_TEMP 2
    
    // 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 = 120000;
    
    // 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;
    
    float lastTemp;
    float lastHum;
    uint8_t nNoUpdatesTemp;
    uint8_t nNoUpdatesHum;
    bool metric = true;
    
    // Initialize motion message
    MyMessage msg(CHILD_ID_MOT, V_TRIPPED);
    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 and Controller
      sendSketchInfo("PIR_DHT_REPEATER", "1.0");
    
      // Register all sensors to gw (they will be created as child devices)
      present(CHILD_ID_MOT, S_MOTION);
      present(CHILD_ID_HUM, S_HUM);
      present(CHILD_ID_TEMP, S_TEMP);
    
      metric = getConfig().isMetric;
    }
    
    void setup()  
    {  
      pinMode(DIGITAL_INPUT_SENSOR, INPUT);      // sets the motion sensor digital pin as input
      
      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)
      wait(dht.getMinimumSamplingPeriod());
    }
    
    void loop()     
    {     
      // Read digital motion value
      boolean tripped = digitalRead(DIGITAL_INPUT_SENSOR) == HIGH; 
          
      Serial.println(tripped);
      send(msg.set(tripped?"1":"0"));  // Send tripped value to gw 
      // Force reading sensor, so it works also after wait()
      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++;
      }
    
      // wait until interrupt comes in on motion sensor. Send update every two minute.
      wait(SLEEP_TIME);
    }
    
    
    
    

  • Hardware Contributor


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