Combining relay and temperature sketch

  • Hey guys!
    I'm trying to combine the temperature and relay sketch from the build section on the website, but for some reason I only see the relays showing up in Domotics.
    I understand that there is a bug in the relay sketch so I have that starting spawning childs at adress 1 till 16. Now I would like to have the temp sensors starting at 17 till 32, but for some reason I can't get it to work......
    Not able to upload my sketch for now.... hoping to get this solved quickly...... Purpose is to automate my greenhouse with aquaponics and hydroponics systems so I need to have 16 relays and 16 ds18b's to monitor the whole process....

  • Mod

    maybe you have something wrong in presentation. Pls post your code. How come you need this many sensors?

  • @gohan thx for your fast reply...
    I wasn't anywhere near my laptop, so I couldn't post the code.

    the reason for that many sensors is:

    pretty big greenhouse with a few aquaponics and hydroponics systems.
    for instance, I have 4 vertical towers from wich I want to monitor the water temp and the temp inside the pvs towers.
    that alone are allready 2 temp sensors and a relay for the pump.....

  • hereby the code that doesn't seem to work...

    // Enable debug prints to serial monitor
    //#define MY_DEBUG 
    #define MY_RF24_CE_PIN 49
    #define MY_RF24_CS_PIN 53
    // Enable and select radio type attached
    #define MY_RADIO_NRF24
    //#define MY_RADIO_RFM69
    #define MY_NODE_ID 5
    #include <SPI.h>
    #include <MySensors.h>  
    #include <DallasTemperature.h>
    #include <OneWire.h>
    #define COMPARE_TEMP 1 // Send temperature only if changed? 1 = Yes 0 = No
    #define ONE_WIRE_BUS 3 // Pin where dallase sensor is connected 
    #define MAX_ATTACHED_DS18B20 16
    unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in milliseconds)
    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. 
    float lastTemperature[MAX_ATTACHED_DS18B20];
    int numSensors=0;
    bool receivedConfig = false;
    bool metric = true;
    // Initialize temperature message
    MyMessage msg(0,V_TEMP);
    #define RELAY_1  30  // Arduino Digital I/O pin number for first relay (second on pin+1 etc)
    #define NUMBER_OF_RELAYS 16 // Total number of attached relays
    #define RELAY_ON 1  // GPIO value to write to turn on attached relay
    #define RELAY_OFF 0 // GPIO value to write to turn off attached relay
    void before()
      // Startup up the OneWire library
      for (int sensor=1, pin=RELAY_1; sensor<=NUMBER_OF_RELAYS; sensor++, pin++) {
        // Then set relay pins in output mode
        pinMode(pin, OUTPUT);
        // Set relay to last known state (using eeprom storage)
        digitalWrite(pin, loadState(sensor)?RELAY_ON:RELAY_OFF);
    void setup()  
      // requestTemperatures() will not block current thread
    void presentation() {
      // Send the sketch version information to the gateway and Controller
      sendSketchInfo("Temperature Sensor", "1.1");
      // Fetch the number of attached temperature sensors  
      numSensors = sensors.getDeviceCount();
      // Present all sensors to controller
      for (int i=17; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
         present(i, S_TEMP);
      for (int sensor=1, pin=RELAY_1; sensor<=NUMBER_OF_RELAYS; sensor++, pin++) {
       // Register all sensors to gw (they will be created as child devices)
        present(sensor, S_BINARY);
    void loop()     
      // Fetch temperatures from Dallas sensors
      // 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)
      // 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>((getControllerConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) / 10.;
        // Only send data if temperature has changed and no error
        #if COMPARE_TEMP == 1
        if (lastTemperature[i] != temperature && temperature != -127.00 && temperature != 85.00) {
        if (temperature != -127.00 && temperature != 85.00) {
          // Send in the new temperature
          // Save new temperatures for next compare
    void receive(const MyMessage &message)
      // We only expect one type of message from controller. But we better check anyway.
      if (message.type==V_STATUS) {
        // Change relay state
        digitalWrite(message.sensor-1+RELAY_1, message.getBool()?RELAY_ON:RELAY_OFF);
        // Store state in eeprom
        saveState(message.sensor, message.getBool());
        // Write some debug info
        Serial.print("Incoming change for sensor:");
        Serial.print(", New status: ");

  • Mod

    I think there is an error in the presentation function: you need to close the first for cycle before the second one, otherwise it will present 2 relays for every Dallas sensor.

  • @gohan again, thx for your fast reply,

    How could I miss that...😳😳 lol...
    I'll try it later today....

    Thx upfront!


  • Mod

    When doing copy/paste of code it can happen to anyone 🙂

  • @gohan apparently..... 😂😂😉

  • Hello,

    I'm trying to do the same thing but with just one relay and a DHT22. So I combined the "air humidity sensor" sketch and the "relay with button" one.

    Each sketch works fine, but when I combine them, I get an error form the DHT
    "Failed reading humidity from DHT
    Failed reading temperature from DHT!"

    But sometimes, I get the temp/hum in the serial monitor. I first thought that I misswired something, but it work perfectly with the other sketch.

    So.. I (obviously) missed something in the program and I can't see what (probably something stupid, I'm new to arduino and mysensors.)

    Here's my code (basicly a copy/paste of the two sketches). Any advice?

    * 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 <>
    * Copyright (C) 2013-2015 Sensnology AB
    * Full contributor list:
    * Documentation:
    * Support Forum:
    * 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.
    * Version 1.0: Henrik EKblad
    * Version 1.1 - 2016-07-20: Converted to MySensors v2.0 and added various improvements - Torben Woltjen (mozzbozz)
    * This sketch provides an example of how to implement a humidity/temperature
    * sensor using a DHT11/DHT-22.
    * For more information, please visit:
    // 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>
    //Relay sketch
    #include <Bounce2.h>
    // 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 2
    #define CHILD_ID_TEMP 3
    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;
    //Relay Sketch
    #define RELAY_PIN  4  // Arduino Digital I/O pin number for relay 
    #define BUTTON_PIN  5  // Arduino Digital I/O pin number for button 
    #define CHILD_ID 1   // Id of the sensor child
    #define RELAY_ON 1
    #define RELAY_OFF 0
    Bounce debouncer = Bounce(); 
    int oldValue=0;
    bool state;
    MyMessage msg(CHILD_ID,V_LIGHT);
    void presentation()  
    // Send the sketch version information to the gateway
    sendSketchInfo("Test403", "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;
    present(CHILD_ID, S_LIGHT);
    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)
    // Setup the button
     // Activate internal pull-up
     // After setting up the button, setup debouncer
     // Make sure relays are off when starting up
     digitalWrite(RELAY_PIN, RELAY_OFF);
     // Then set relay pins in output mode
     pinMode(RELAY_PIN, OUTPUT);   
     // Set relay to last known state (using eeprom storage) 
     state = loadState(CHILD_ID);
     digitalWrite(RELAY_PIN, state?RELAY_ON:RELAY_OFF);
    void loop()      
    // Force reading sensor, so it works also after sleep()
    // 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: ");
    } else {
      // Increase no update counter if the temperature stayed the same
    // 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: ");
    } else {
      // Increase no update counter if the humidity stayed the same
    //Relay voidloop
    // Get the update value
    int value =;
    if (value != oldValue && value==0) {
        send(msg.set(state?false:true), true); // Send new state and request ack back
    oldValue = value;
    void receive(const MyMessage &message) {
    // We only expect one type of message from controller. But we better check anyway.
    if (message.isAck()) {
       Serial.println("This is an ack from gateway");
    if (message.type == V_LIGHT) {
       // Change relay state
       state = message.getBool();
       digitalWrite(RELAY_PIN, state?RELAY_ON:RELAY_OFF);
       // Store state in eeprom
       saveState(CHILD_ID, state);
       // Write some debug info
       Serial.print("Incoming change for sensor:");
       Serial.print(", New status: ");

  • Mod

    try to put a wait(500) at end of loop function, or even wait(1000)

  • This post is deleted!

  • @gohan said in Combining relay and temperature sketch:


    Oh.. like I said : something stupid..

    Thanks a lot. 🙂

    I also had "#define MY_NODE_ID 7", because I couldn't see the relay on my Vera.

  • Mod

    DHT sensor doesn't like to work very quickly, it needs some resting time between measurements 😄

  • @gohan modfied my code..... still the same.... I get 16 children (relays) and no temp...... I have 4 ds18b20's connected.....
    And I get the error switch command on the relays....😑😑

  • Ok, now I have another problem.

    When I build the relay/dht node, I first made the thing work with the relay with button actuator sketch alone (the DHT was plugged, but it was an additional feature I wanted to add).

    Now, it seems that my power source doesn't have enough power to make the relay to close. The led on my relay board blinks when the relay is on and off, but nothing.

    That's weird.. I'll try running the relay sketch alone, just to see.

  • Mod

    @Tim76 ok, let's go back to the beginning. Try with one sensors only, if everything works then add one relay, then add the second and keep adding the sensors until you see something wrong. You need to go step by step, otherwise with all that stuff you have it will be impossible to debug.

  • @gohan ok

  • @gohan both sketches work perfectly stand alone.... but I think the problem lies within the assingment of the child id's...
    James Bruce talks about this "bug" in his video on how to combine sketches.....
    They relay sketch assigns from 1 to 16
    And the temp sketch assigns from 0 to 15
    So they both try to use the same id's for their children when you try to combine them....
    I need a way to get around that and have relays on 1-16 and temp on 17 to 32......
    Or there might just be the same "bug" in the temperature sketch.....😬😬 wich might mean that they can't be combined for now......😒😒

  • Mod

    if use something like this in presentation?

    for (int i=1; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
         present(i+3, S_TEMP);

    you get the idea, just shift the child id of the dallas sensors and leave the first 4-5 IDs for relays

  • @gohan aha! Will be trying that later tonight..... I'll keep you posted! 😊 Thx man!

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