I am currently trying to make a fully automatic potato/carrot/wheat farm utilizing composters, and a fully-automatic sugarcane farm. I have everything figured out and working up until the bone-meal grows the plant and the plant is ready to be harvested. I need a way to somehow detect the plant is fully grown, output a signal so the plant can be harvested and a new plant be put in it's place. I can't rely on timings (e.g. how long it takes for the plant to be fully grown by the bone-meal) because of the slow and slightly sporadic rate that my sugarcane farm produces sugarcane. Any Ideas?
The only thing I could think of is using a combination of T flip flops with observors. I assume an observor outputs a redstone signal everytime the food grows? Take that output and feed it to a couple t flip flops in series. Say it has 6 phases before it's grown. I would take 1 observer. And then feed it into 3 T flip flops in a row. That way on the output of your final t flip flop you then activate what you use to collect the food