Newbie wants to do everything wired



  • Hello together,
    I see that here are the experts of sensors for smart buildings.

    I build some years ago my smart home with the general idea to keep as much as possible everything wired.
    I prepared to each heating distributor a LAN cable and from the heating distributor a 4x0,8qmm cable do the sensor pleace for each room.
    Now I would like to put a gateway in each heating distributor which collect all the data from the sensors in the room.
    Nice to have would be to have in each room a temp, humidity, light & move(rf) sensor.
    My issue is now that I have only 4 signal(wire) to the gateway, so that I need sensor which have the same fieldbus or I2C or something else.
    The latest would be to have a microcontroller on the sensor side which collect the sensor data and send it to the gateway.

    Would be great if you can advise if there is some suitable solution for my requirements.
    I would like to use only wired connection no rf.
    Best regards


  • Mod

    Welcome to the MySensors community @tweaker

    MySensors with rs485 transport should fit your use case pretty well.


  • Mod

    Easiest way to get started is probably to read the getting started guide, keeping in mind that MySensors also supports wired rs485 where the guide talks about radio.

    Then look at the various build guides, for example
    https://www.mysensors.org/build/temp



  • @tweaker As @mfalkvidd said RS485 is a good solution if no ethernet is available - Absolutely DO NOT use I2C for any length of cable over a metre or so, it was never designed for that, only for onboard PCB communication.



  • @mfalkvidd said in Newbie wants to do everything wired:

    MySensors with rs485 transport should fit your use case pretty well.

    Getting back to your request, you need some kind of wired protocol to discuss between your sensors and your gateway.

    Depending on cables you have, max speed of communication will vary. With UTP/STP CAT 5 or more, you may think about Ethernet. With less sophisticated cables, any serial protocol will do it. You may think about 2 end points system (RS 232) or multi-node (RS485).

    As soon you have defined the physical layer, you have to think about the format of packets to be exchanged. Obviously, MySensors do it properly, and is already integrated (throughout gateways) to some popular controllers.

    This is probably the reason @mfalkvidd advice you to use RS485 with MySensors πŸ˜‰



  • Thanks for the reply.
    A rs485 sounds pretty good.
    Do we have already a cheap board to put temp humidity motion sensor together on a mySensor board?
    I was thinking already about the si7021 Sensor and an cheap rf sensor with an digital output.
    As an gateway I have a orangePi Zero with nodeRed in mind.


  • Plugin Developer

    There's also a proposal to add PJON support: https://github.com/mysensors/MySensors/issues/1171

    As far as I can tell @tekka has even created some code to that effect. More no that here: https://github.com/mysensors/MySensors/pull/1278



  • If you are thinking about RS485 system, have a look at my hardware:
    https://www.openhardware.io/user/2098#view=projects

    If you like it, please feel free to contact me. We've made some significant progress, which is not published yet.



  • @feanor-anglin said in Newbie wants to do everything wired:

    If you like it, please feel free to contact me. We've made some significant progress, which is not published yet.

    I am also intresting in implementation of RS485 in my MySensors network, and i like yor hardware and use some of your ideas in my project Simple compact RS485 node (ATmega328 + MAX485) ,



  • Thanks for the proposal.
    I have still one concern to use RS485:
    My topology would be star topology, but RS485 is not designed for that.
    Do someone have already experience with that?
    Will it work with a lower baudrathe around 19,2k?
    How big delay can I expect by using a motion detection sensor to switch on the lights?



  • @tweaker
    I'm also plan to use star topology, but still i build just one node πŸ™‚
    Use 9600 baud rate, and i don't have delay on my experience on this day.



  • @cabat : Thanks for sharing. When do you plan to connect more nodes? How long will be the cables?

    General Question: I saw as well the ESPhome.io which looks very nice for me. Is this something which can be combined with the mySensors protocol? I want to use NodeRed in the OrangePi Gateway to gather all the sensor values.



  • @tweaker said in Newbie wants to do everything wired:

    @cabat : Thanks for sharing. When do you plan to connect more nodes? How long will be the cables?

    In fact now i have 2 nodes, but one of then only for testing purpose, sending temp every 15 seconds.
    The cable is about 10-15 meters.



  • Do you have already more experience with more then 4-5 Sensors.



  • @tweaker still not - not enough time to assemble additional nodes..

    I have encountered problems that are still not clear to me when assembling the second board - it does not want to connect to the gateway.
    I checked everything that is possible, but I haven’t found the reasons yet..
    I will plan To assemble one more test node ..



  • Star topology is not recommended to use with RS485, but it is not that it certainly won't work. You have to test it.

    When it comes to experience, I have one with much more than 5 modules. It works pretty good, even if the modules are badly designed. To achieve top reliability though, you have to use well designed modules.



  • @feanor-anglin said in Newbie wants to do everything wired:

    Star topology is not recommended to use with RS485, but it is not that it certainly won't work. You have to test it.

    I know about it, but I hope that with a speed of 9600 and a small cable length it will work ..


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