Thanks for taking the time to have a look at this.
It is a Spaform SF273 controller which is currently connected to a VL801D top panel.
https://www.hottubpartsuperstore.co.uk/balboa-spaform-sf273-licensed-pcb-52604.htmlhttps://www.hottubdiy.co.uk/balboa-vl801d.htmlI cant seem to find anything about the controller/top panel protocols or pin-outs anywhere.
The post you suggested was actually the inspiration for me looking into the project which is very much a learning project for me although there appears to be many differences in our setups.
My top panel connects to the board via an RJ45 connector which has voltages across 7 of the 8 cables. One of the cables appears to be totally dead and therefore I have disregarded this (maybe a mistake??)
The top panel itself actually has 8 buttons for each of - Program, Mode, Heat Up, Heat Down, Blower, Pump 1 (2 speed settings), Pump 2, Light.
My controller has a second RJ45 port which I believe to be available for a second remote controller and also have some soldered blanks on the board that are marked computer port and SPI hence leading me down the track of assuming some form of an SPI interface.
I have conduced some basic continuity tests with the system powered off to see if the soldered blanks marked SPI are connected to lines of the controller port and they appear to be.
I hadn't really considered cross-talk as an issue and if I am totally honest dont understand it. I have conducted the tests via a simple board that I have put together consisting of a flat 8 core cable (actually an old Cisco light blue console cable if you are familiar with these) terminated onto some perfboard. Each of these goes into a 500 Ohm resistor then out to a loose jumper cable approx 6-7 Cm long. These plug direct into the logic analyzer. The cable from the board is approx 1.5m. Is this likely to cause cross-talk problems? I must confess they the jumper cables were not arranged neatly for the test and therefore could have looped over/under each other.
Do you think I should repeat the tests with more rigor about cable routing and/or at a higher sampling rate?
Interestingly on one of these tests I conducted it actually caused the controller to reduce the heat setting - could this indicate cross-talk? I tried to replicate this by tracing one wire at a time but the scenario didn't repeat.
I had assumed given the number of buttons on the controller that it wasnt simply a case of each of these being a gpio based push button and being controlled via some form of interface but I am totally confused by what I have seen.
Any further help would be appreciated.
Thanks