@tinnut Set each GPIO you use as a slave select to be an output and set it high
some info to do it in terminal other then scripts and code
or use a library as WiringOP
or even better buy a Orange Pi for 10 euro and check your pins of your opensprinkler pcb most likley you only have it to turn around RPi is right to left and a OPI is the io pins from left to right .
Get Armbian and have mainline kernel and up to date linux distro