I just tossed a Raspberry Pi (old model 1b) into my control system and with the help of influxdb and grafana I have beautiful graphs and can control my pool quite nicely. Here are the details:
- Raspberry Pi - running raspbian
- rs485 shield (for GPIO serial)
- connected to a Pentair EasyTouch system control via the "com" port (just +/- rs485 feeds)
- separate ubuntu 16.04 server (actually Zentyal for home domain controller)
- on this server sits influxdb and Grafana - the dynamic duo for DYI awesome time based data graphing
On the Raspberry Pi I run two "services" (both actually pretty hacked together ruby scripts right now that I run in separate "screens" with good'ol linux screen)... one to read all data on the rs485 serial and send all stats I have it set to catch to influxdb. Second is a service I call "send_to_pool" which is just a very light weight http server that takes in webservice like commands... creates the hex data commands to send over the rs485 and returns the most basic statements back. I'm trying to make the Pi as "dumb" as possible and just really working as a blind layer between my Grafana/influxdb front end and the pool equipment.
On the Ububtu side I have Grafana graphing everything in influxdb (temps, heater, modes, pump watts/rpms, etc.) I then created the cheesiest html panels with some very basic on/off controls for various things.
I'm currently taking my franken-code "script" and turning it into a good library I plan to toss up on github.
I'm out about $25 for the Pi and $10 for the rs485 shield - only been going for about a week now and just got the controls working yesterday even.
With all of that... I would highly recommend the use of a Raspberry Pi for a pool control system!