Thanks for the response Ray. I suspected that the Arduino shield would not be hardware compatible with the Raspberry Pi and thanks for confirming.
So now I am wondering if a networked Arduino with an OSBee Shield could be made to look like a “remote IP station” to my main OSPi controller. This way the Arduino with OSBee Shield could drive the latching valves of my indoor system and my OSPi could drive the outdoor valves and act as the combined central control system.
I know the new “remote IP station” functionality is meant to allow one OS to control another OS. But looking at the 2.1.6 firmware code, the Master appears to be sending just the “cm” command to the Slave. Is that right ? The OSBee web server and sprinkler timer examples look to have all of the component parts of the logic needed to listen for a “cm” command and drive the latching valves. But maybe I’m missing something ?
I’ll admit a somewhat convoluted (and expensive) way to integrate an indoor watering system but maybe I can rationalise it as a learning opportunity !