Display node: how to set up



  • Hello,

    I would like to create a display node (1602 or 2004) with the possibility to show measurements of other node(s).
    How do I approach on this? What is the way to work with MySensors.

    I would like the display node to be available in the living room with the ability to show for example the data from my weather station (multi sensor node). On top af that this display node can act as repeater node.

    Will in such case this node receive data directly from the weather station node or do I have to retrieve the data for this node from the pimatic database?
    How do I implement this?

    Thanks for any suggestions :simple_smile:


  • Mod

    @Petjepet have you looked at the display example? It shows time and temperature fetched from the controller. Seems quite similar to what you want to build.



  • @mfalkvidd yes I did and believe it is showing the RTC data of that same node. It gets the time initially from the controller by a specific for the system time available function 'requestTime()'.

    How would I for example get the temperature from a particular node in this display node?
    So how to refer to that particular node and the temperature attribute in the sketch of the display node?
    Is there a kind of function 'requestValue(NodeId, SensorId)'?



  • @mfalkvidd
    Example show temp from DS3232 RTC


  • Mod



  • @mfalkvidd Thanks! I'll have a look.



  • @mfalkvidd to start right:

    The function 'void receive(const MyMessage &message)'
    This will catch all data being send from nodes?
    I will have to identify what type the data is and from which node and sensor the data came and if the node is correct use that data to update the display with?

    The function 'void request(uint8_t childSensorId, uint8_t variableType, uint8_t destination);'
    This function will request directly data from a particular node and sensor.
    Probably not the way to go when the sensors are battery nodes since this function will activate the battery nodes often.

    The receive function would fit better but I have to investigate how to determine the node and sensor the data received is coming from. Is there an example for this?


  • Mod

    the receive function will be called every time the node receives a message destined for that node.

    The message object can be examined by checking the contents of the message. More information: https://forum.mysensors.org/topic/6351/interperating-messages-from-controller/4

    Nodes that are sleeping will not be woken up. They are sleeping, so they can't know that they should wake up.

    The easiest way is probably to either have the other nodes send the data to the display node, or have the other nodes send the data to the controller and let the display node query the controller.

    This thread might give some more information https://forum.mysensors.org/topic/826/node-to-node-communication



  • @mfalkvidd thanks for the info.

    I came up with this and verification of the sketch is ok in Arduino IDE:

    void receive(const MyMessage &message)
    {
      // Explore message
      if (message.sender == 38) // weatherstation node
      {
        switch (message.sensor)
        {
          case 0:  // Humidity sensor
          {
            lcd.setCursor ( 0, 1 );  
            lcd.print("Hum: ");
            lcd.print(message.getFloat());
            lcd.print("%");
          }
          case 1:  // Temperature sensor
          {   
            lcd.setCursor ( 0, 0 );  
            lcd.print("Temp: ");
            lcd.print(message.getFloat());
            lcd.write(223); // Degree-sign
            lcd.print("C");
          }
          case 2:  // Light sensor
          {
            lcd.setCursor ( 8, 1 );  
            lcd.print("L: ");
            lcd.print(message.getUInt());
            lcd.print("Lux");
          }
          case 3:  // Barometer sensor
          {   
            lcd.setCursor ( 8, 0 );  
            lcd.print("P: ");
            lcd.print(message.getFloat());
            lcd.print("mBar");
          }
          case 4:  // Barometer Temperature sensor
          {
          }
          case 5:  // Rain sensor
          {
          }
        }
      }
    }
    

    Is this the way to approach ?

    I still have some questions about the concept:

    • When I use the 'receive' function in this display node, will the message still be received by the gateway?

    • In general: can messages sent by one node be receive and evaluated by multiple other nodes in parallel?


  • Mod

    @Petjepet yes that could be the right approach, assuming you have nodes 1-5 sending data to that display node.

    Depending on you network setup, they gateway may receive and forward the message.

    Broadcast messages are possible (by sending to destination node 255). I am not sure how they work though, I have never used them myself.



  • @mfalkvidd actually it is one node having 5 sensors.

    My setup is one gateway with multiple nodes (4 PIRs, 1 Temperature, 1 Humidity and the weather station with 5 sensors).
    These nodes just use the standard 'send' function. This is a broadcast, isn't it, since no destination node is provided in this function?

    The gateway picks up these messages of the nodes (as I can see them in my controller Pimatic) and I hope the display node will pick the message up as well.
    Or does the receive function only pick up dedicated sent messages from other nodes?
    If this is the case I will have the display node to query the controller. No clue how to do that.

    I'll build the display node tomorrow to test the sketch I have now and see if it receives the data of node 38 (weather station and its 5 sensors).


  • Mod

    @Petjepet said in Display node: how to set up:

    @mfalkvidd actually it is one node having 5 sensors.

    Yes, you're right. Sorry about the confusion.

    My setup is one gateway with multiple nodes (4 PIRs, 1 Temperature, 1 Humidity and the weather station with 5 sensors).
    These nodes just use the standard 'send' function. This is a broadcast, isn't it, since no destination node is provided in this function?

    No. The default destination for messages is the gateway, so they will only be received by the gateway.

    The gateway picks up these messages of the nodes (as I can see them in my controller Pimatic) and I hope the display node will pick the message up as well.

    No the display node will not receive the messages unless the messages have the node as destination (message.setDestination() )

    Or does the receive function only pick up dedicated sent messages from other nodes?

    Correct

    If this is the case I will have the display node to query the controller. No clue how to do that.

    Use the request function



  • @mfalkvidd I'm getting there in time ๐Ÿ™‚
    Thanks for all the patience you have in explaining.

    Using the message.setDestination() function would then be an option to implement/add in the weather station node for each of the 5 sensors?
    The drawback would be to reprogram the weatherstation which is fully operational now.

    Using the resquest function in the display node would want to activate the weather station (being a battery node in my garden) which uses the sleep mode and that would not work as documented.

    As said before I would also want to use the display node as a repeater.
    This would make it a kind of gateway in passing through data.
    Is there a possibility there to evaluate the weather station node data?

    You also mentioned a way to get the data from the controller (Pimatic in my case).
    How can I request data from the controller/gateway?
    Or is there a way to let the controller/gateway send the data to the display node?

    Maybe I'm looking at this issue in the wrong way.
    All I would like to do is display data from a battery operated sensor node on another node.


  • Mod

    @Petjepet said in Display node: how to set up:

    @mfalkvidd I'm getting there in time ๐Ÿ™‚
    Thanks for all the patience you have in explaining.

    Using the message.setDestination() function would then be an option to implement/add in the weather station node for each of the 5 sensors?
    The drawback would be to reprogram the weatherstation which is fully operational now.

    Yes

    Using the resquest function in the display node would want to activate the weather station (being a battery node in my garden) which uses the sleep mode and that would not work as documented.

    As said before I would also want to use the display node as a repeater.
    This would make it a kind of gateway in passing through data.
    Is there a possibility there to evaluate the weather station node data?

    Maybe. I don't know unfortunately.

    You also mentioned a way to get the data from the controller (Pimatic in my case).
    How can I request data from the controller/gateway?

    I think you can just request the data from the gateway and the controller will respond but I am not sure.

    Or is there a way to let the controller/gateway send the data to the display node?

    Some controllers have the ability to do stuff when messages are received. I think Domoticz uses lua for that. I have not done anything similar myself though.

    The pimatic area of the MySensors forum seems to be a very quiet place ๐Ÿ˜ž


  • Mod

    Reprogramming the weather station it would only be a matter of adding the extra send commands to the display.
    I was also thinking that this would be a case where mqtt would come handy, since you can get all the sensor data from pretty much anything that has an ip connection to the mqtt server.



  • @gohan I would like to leave the weather station reprogramming as the last option since it was built in the v1.5 period and calibrated. Never try to repair a working device ๐Ÿ™‚

    In general I would like to develop a solution where display nodes can be added to the network not having to change other nodes for that. The independency of using display nodes without having to change sensor nodes would be great to achieve.

    @mfalkvidd I'll try to find out how to request data from the gateway/controller of a specific node. As long as the Pimatic controller is showing the data there must be a way to get it from there. Search the Pimatic forum for now.


  • Mod

    @Petjepet
    If you want more flexibility, I think mqtt is the best solution as you can add as many displays as you want, you could make an esp8266 mqtt gateway with display and nrf24 radio (if needed) or just an esp8266 with display with simple mqtt client (not mysensors) that subscribes to topics in the mqtt server and displays values.



  • This post is deleted!

  • Mod

    Did you try to add some serial print in order to check if that code in receive function is actually executed?


  • Hero Member

    @Petjepet I have not done a lot with the request feature but here is how I understand it works.

    A node can make a request to the controller for information about its own child sensors by using request in its sketch. Typically this would be in the loop section of the sketch. The request is issued with the following line.

    request( sensorId, messageType)

    So if you had a binary switch sensor with a child id of 1 and you wanted to check on its status you would write it like this.

     request( 1,   V_STATUS);
    

    The request is then processed by your controller and the result is returned to the node that sent the request. You then need to have code on that node to do something with this information.

    As you have already noted this is where the void receive function is used.

    So for our example of a binary switch we could use something as simple as this

    void receive(const MyMessage &message) {
      
      if (message.type == V_STATUS) {
    
        //put code here to be executed when the return from the request arrives   
       }
     }
    

    If you have more than one child sensor that you are expecting returns from you could extend the code using message.sensor to test for which sensor the return is for.

     void receive(const MyMessage &message) {
    
      if (message.type == V_STATUS) { 
        switch (message.sensor) {
         case 1:                          //incoming message is for  sensor 1
             // put code here to be executed when the message is for sensor 1
           break;
         case 2:                       //incoming message is for sensor  2
             // put code here to be executed when the message is for sensor 2
           break;       
       }   
     }
    }
    
    

    If you wanted to separate returns from a request from normal messages from your controller. You can use message.getCommand()
    If you look in the send and receive serial data for your node you will see the command type for a request shown as c=2 , so you just need to test for type 2 commands.

     void receive(const MyMessage &message) {
    
         if (message.type == V_STATUS) { 
           if (message.getCommand() == 2){
             // put code here to be executed when the message is from a request
           }
           else {                                                             //process the message as per normal
              switch (message.sensor) {
                 case 1:                                                     //incoming message is for  sensor 1
                   // put code here to be executed when the message is for sensor 1
                   break;
                 case 2:                                                     //incoming message is for sensor  2
                   // put code here to be executed when the message is for sensor 2
                   break;       
              }   
           }
         }
     }
    
    

    Making a direct request to another node is also possible. To do that you can use the optional third parameter in the request statement which is for the node id that you are requesting information from.

    The default is set to 0 which is the gateway but you can use the node id to select another destination.

    So if we wanted information from a binary switch sensor with an id of 1 which is on a node with an id of 20 we would do this

     request( 1, V_STATUS,  20);
    

    The gateway will rout this request to the desired node but it will be up to you to have code on that node to both read the request and then send a reply back to the node that asked for the information. Of course you will also need code on the sending node to process the request when it is returned



  • @Boots33 Thanks for the explanation!
    However, as mentioned in an earlier post, I can't directly request data from the weather station node since it is battery operated and uses a sleep to save power. In this case the node will not react to a request.

    I'm now using the receive command exactly in the way you mentioned by determining the sensor in the message to get the correct data for the right value to display in my Display node.
    In Pimatic I set up a rule to send the data of the latest received value of the weatherstation node, triggered by a change of that value (when weather station node is sending a new value). The point is now that this is a push functionality by Pimatic where I'm looking for a pull mechanisme to be done by the Display node to Pimatic.


  • Hero Member

    @Petjepet I don't have experience with pimatic but would assume you can use a similar mechanism I use in Domoticz and MyController.

    • Have you display node define "sensors" for the variables to display. These will be available (and "requestable") in your controller.
    • Do some programming (rule or other magic) in your controller to copy the Weatherstation reported values to the display "sensors".
    • Let the display node request()/"pull" the value from the controller.

    As my display nodes are pretty dumb displays I let the controller built "V_TEXT" containing the formatted display information. An ancient example.
    0_1489393901933_upload-275f0f01-bcc2-4114-aa7f-4a8d66a1be0d



  • @AWI

    @AWI said

    • Let the display node request()/"pull" the value from the controller.

    This is where Pimatic fails. I can't request info of any node from the controller even not from the node itself.


  • Hero Member

    @Petjepet Is there a reason why you do not want to use the push method



  • @Boots33 Display nodes are convenient in monitoring status of other nodes. I would like to have a Display node in the lead for this (on request).
    In this way new Display nodes can be set up more easily without having to update the controller for each change on Display nodes.
    If Pimatic would be able to handle the 'request()' for the node doing the request it would be great I think (like your solution).


  • Hero Member

    @Petjepet I am not familiar with Pimatic but could a workaround be that you add a binary switch sensor to your display node and then have it trigger the switch when it requires data from the controller.

    Then on the controller have it send the data when it sees a change on that switch.



  • @Boots33 That's how I plan to do it now. But for every new sensor value to get to the Display node (or when building a new Display node) I also have to update someting in Pimatic. That's what I would like to get rid off.


  • Mod

    Sorry if I stress, but did you think about using mqtt?



  • @gohan Sorry I didn't answer that this weekend.
    I tried many times before to build a ESP8266 Gateway and ended up in frustrating continuous reboot issues.
    So I gave up on that.
    I have now a Serial Gateway working fine.

    How would a MQTT gateway benefit more in the issue I have not being able to directly retrieve data from the controller?


  • Mod

    There are some videos on youtube explaining what MQTT is, but basically if you have your Mysensors gateway publishing to an mqtt server/broker you can have multiple clients subscribing to the same topic (or different ones too, depending on the needs) so that as soon as the node sends the data to gateway, gateway publishes that data on the mqtt server, mqtt server sends data to all mqtt clients that have subscribed to the topic where the data have changed. This way you have push updates on the display nodes and you can configure mqtt to retain last published data from the sensors.

    Of course you would have to configure you controller to use the mqtt server instead of serial. I am running Domoticz connected to mqtt with mysensors and it is working fine. Using MQTT it allows also to quickly connect other programs like node-red or whatever controller/dashboards without too much effort



  • @gohan thanks for the info.
    I'll look into it and see if the transition is worth while.


  • Mod

    @Boots33 I was wondering if the request function could be used to set the sleep time from the controller, like when the nodes wakes up it requests the value of the "sleep" sensor and then goes back to sleep with that new value in case it has been updated (is would kind of a bad copy of the smartsleep)


  • Hero Member

    @gohan That is a novel idea. Never tried it but i would think it should work as long as you can change the value on your controller. it should be simple enough to load the returning value into the sleep variable.


 

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