Hey, i have been looking into using wireless sensors and came across using MQTT. After seeing how cool that is i began rethinking my design for irrigation setup. I am looking for a design that i can easily reproduce and expand. i made a couple drawings to give you guys a gist of what i am trying to accomplish...
As of right now i already have my system finished and working with just water counter, solenoids, relays and a GUI with tkinter i made to manually feed plants (viewtopic.php?f=37&t=216270&p=1330002#p1330002). I am adding moisture sensors to my existing setup to allow full automation. With my current setup i do not need wireless sensors, the relay boards i have that attach onto my Rpi have additional input/output pins --- https://www.sequentmicrosystems.com/ind ... egaio.html
Onto my actual point in this post... refer to my attachments you will see i want to use multiple RPI to control a large area and many sensors/solenoids. a friend of mine is going to use my system inside his building (5000 + sqft). My current system i need to run wiring to every single solenoid (2), every single soil sensor (2), a relay for each solenoid (8 per board / max 32 per RPI). So you can see how using just one RPI to control it all would be a disaster wiring wise and would max out with relays pretty quickly.
A ESP8266 got me thinking that would work perfectly however, i would still have to run wires to the solenoid from the RPI as the ESP8266 would be unrealistic to use with 8+ relays, mine as well just use a RPI and seperate the building into "quadrants" each section would have a RPI with on board relays and the pins to connect the soil sensors. no need even for a breadboard. Example would be 1 RPI with relay board attached controlling 8 solenoids with 8 soil moisture sensors. Then just copy that setup for each "quadrant". The final RPI would control the reservoir, counter, pump, mixing nutrients and receiving the input from other RPI moisture sensors to tell when to feed. Obviously during the feeding process the solenoids would turn on/off based on the water meter.
The only downfall i can think of is the delay with main RPI counting water and telling another RPI to close a solenoid and open the next. Honestly not sure how much of a delay would exist to send message using MQTT. Hopefully my pictures work and you also understand my giberish lol