Multiple Pi's for home automation control


#1

Absolute newbie alert :slight_smile:

Am starting on a home automation project and have been looking at advantages / disadvantages of using multiple pi’s for data acquisition and control.

Simple scenario

Temperature for heating circuits (radiators) in a home can be varied depending on outside and inside home temparatures to save energy. Lower outside temperatures require higher radiator temperatures inside home and vice versa.

  • RPi 1 with weather station type sensors
    External Temperature
    Internal (home) Temperature

  • RPi 2 Heating system sensors / control
    Heating water temperature sensor
    Motorized mixing valve that controls temperature to heating circuits / radiators
    Heating circuit water temperature sensor / return water temperature sensor
    Motorized valves (on off) to isolate 2 areas of house living / sleeping (living area temperature can be decreased during night hours, sleeping areas increased and vice versa during daytime. etc etc

Can the input(sensors) from RPi 1 be used to pass a value to RPi 2 so that the motorized mixing valve can be controlled to adjust the water temperature to radiators to the correct value using Cayenne?

The reason for using multiple RPi’s is that my heating system is in the basement and the cost of using remote sensors, wiring, range extenders etc for an external weather station would equal or even more than adding a RPi dedicated to certain tasks. Above is just a simple scenario. I have two heating circuits and heating sources solar collectors, fireplace boiler, furnace and separate tanks for heating and potable water so the actual project is quite complex requiring quite a few temp sensors and controls, enough to keep one RPi ‘busy’ Not to mention it would be much clearer to have RPi’s dedicated to specific tasks that can work together instead of becoming a very complex jumble…

Would the Cayenne dashboard be able to combine sensors from one or more RPI’s and send those values to other RPi’s?

My question is more about feasibility of using Cayenne for such combined applications rather than technical issues before ‘diving in’.

Thanks for any helpful input or suggestions!

  • Brian

Combining multiple RPi's into a distributed 'system' within Cayenne
#2

Currently it’s not possible, but it’s definitely a good idea that I think should be supported. You could technically do it with the MQTT API, but it would take some coding to achieve it. Here is an example of using Python to send values to Cayenne with MQTT Cayenne MQTT Python Library


#3

Thanks Adam!

Fortunately this is very early stage for this project so will keep an eye on the MQTT API developments for the RPi . I’ll also post as an Idea/Suggestion and see what happens to add support for such. Once I get two RPi’s running their separate tasks I can try to tackle MQTT. Enough fun at the moment with ADC’s using existing PT1000 sensors already available in the old heating system and DS18B20’s strung through the house :wink: Should be a fun project for me and my 13 year old son.
Cheers!