does anyone know how you program a Real Time clock with a led strip or if you need to do this with 2 separate programs? I need to make a small greenhouse but don't really know how to use it to regulate the lighting it needs to burn 20h but to test just a few minutes.
20h for plants ? just switch on / off ? why you need a realtime clock ? u need so much precision ?
please describe your idea in a more detailed way .
off the shelf programmable timer comes to mind, why do you need arduino?
Get the time from the RTC and break into hours, minutes etc. Check if the hour is greater than the specified start hour and switch leds on. Check if hour greater than start hour plus 20 and switch leds off. The simple approach will work if the duration falls within 00.. 23. If you start hour is e.g. 5 and duration is 20 hours, it becomes a little trickier.
I suggest that you look at some RTC examples for the library that you picked.
Welcome
A LED strip isn't powerful enough to light a plant and expect it to grow, you need high power LEDs (and a lot of them), or a special lightbulb of hundreds Watts. Or is it only for decoration ?