Minor revisions (4) and (5) are on Github but they are not officially released/announced. (4) addresses the issue caused by breaking changes in GPIO controls with Raspbian Bookworm; (5) fixed an issue introduced in (4) that only affects OpenSprinkler 3.x and it’s not relevant to OSPi/RPi. So neither of these two versions changes the HTTP API which remains the same with minor revision (3).
MQTT instructions can be found on our support website:
https://openthings.freshdesk.com/support/solutions/articles/5000859089-how-to-use-mqtt
It currently only supports outputting information through MQTT (i.t. MQTT publishing). You cannot yet use MQTT to trigger an action on OpenSprinkler (i.e. MQTT subscription). It’s quite easy to modify the firmware code to implement subscription. The last time we tried to do this, the developers did not agree on the APIs to use so we stalled there (then the pandemic happened and things got slowed down dramatically). So if you want to trigger an action, at the moment you need to either use the HTTP API, or implement MQTT subscription yourself.