App or integration for complex scheduling?

I would definitely take a look at Node Red, which is included as an add on with Home Assistant, but will also work with Smartthings. We discussed Node Red on some other threads:

Specifically, there are “palettes” in Node Red that are like little programs that create nodes to link services, like Smarthings devices, Home Assistant Entities, Google, etc together to perform automations. For me there was a steep learning curve at first, but well worth it. I’m sure its something you can take on if you’re already familiar with Webcore and treading into Home Assistant. Once setup, these palletes look very promising. One can use the Google Calendar to trigger automations, the other uses the UI dashboard in Node Red itself to schedule which sounds a lot like what you are looking for.

time-scheduler-demo

1 Like