Static Node ID and other Unanswered Questions

  • Hello all,

    This website is pretty awesome, however, there are some things that I could use clarification on. (It might be a good idea to make a simple FAQ section). The main questions are bolded.

    I don't want to use a controller. The application I am working on will have at most 10 sensors, no repeaters, and one gateway/main hub, which will work almost in reverse. The main hub will have sensors attached to it, and will send out commands to the sensors to light LEDs. The application will be extremely low power, meaning the sensors will most likely sleep, waking every percentage of a second to check for a message.

    Doing some searching, I've found out that the controller (not the gateway) usually hands out ids to the sensors, however, since I won't have a supported controller connected, I would like an example of how to best assign static id's to sensors. What are all of the arguments? Do I first have to clear the eeprom? Do I type "gw.begin(5);" to assign id 5 to a sensor?

    To start, I've set up a gateway device using code for an arduino, and set up a sensor node using the DHT humidity example. (Some codebender options give compilation errors as well, but that's a different subject)

    I did find a post for a repeater node and modified the "gw.begin();" to "gw.begin(NULL,4,false);" and there is communication, but there is not a good break down of what exactly I'm seeing in the arduino serial monitor, even in the API. Below is the output that I see from the gateway:

    0;0;3;0;14;Gateway startup complete.
    0;0;3;0;9;read: 4-4-0 s=255,c=0,t=17,pt=0,l=5:1.4.1
    0;0;3;0;9;read: 4-4-0 s=255,c=3,t=6,pt=1,l=1:0
    0;0;3;0;9;read: 4-4-0 s=255,c=3,t=11,pt=0,l=8:Humidity
    0;0;3;0;9;read: 4-4-0 s=255,c=3,t=12,pt=0,l=3:1.0
    0;0;3;0;9;read: 4-4-0 s=0,c=0,t=7,pt=0,l=5:1.4.1

    I know it's communicating because of the word "Humidity", however, I don't understand the output from the serial monitor. Can someone explain this? I'm using the DHT11 sensor. I also don't understand why I stop receiving output. The devices sat for 5 minutes after initially being plugged in, but the output above is all that was received.

    Lastly, is there any more information about using the sleep command? The NRF chips have several sleep/standby options, as does the AT328p. I'm guessing the power down mode is the only option supported. Can I get the gateway to resend a message to a sensor until it receives a acknowledge? This will be important if I have the sensors sleeping for percentages of a second.

    Thank you for all of the hard work!


  • Admin

    You have found the correct way of assigning fixed node id's, with gw.begin(null,4,false);
    It's kind of embedded in the apI description here

    For the serial communication part, there is a description of the protocol on, look for the strings that start with 4 (your node id)

    For the retransmit question, have you thought about reversing things, and let the nodes request updates when they wake up, instead of the gateway transmitting things to a node that might be a sleep.

    Something like:
    node hey i'm awake, give me some data
    gw ok here you are
    node thanks, goodnight

  • Does this help:

    I agree with you that the serial messages are not perfectly documented, but realise that this site has been made (as far as I know) by a bunch of people that share their 'love' for home automation.....


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