No, just succinctly summarising the situation.
It's the XY problem yet again. Happens so often here.
You are asking for help in pursuing the wrong solution to a problem because you did not understand the real problem and are "clutching at straws".
You are not following the instructions; you have not cited what components you were using (which is to say, what sensor, what level shifter, what MCU, what other components, given a connection diagram and a photograph of the troubled setup and explained how you are providing power).
No wonder you have received so few replies - we really have no idea what you are doing, right or wrong and contributors tire of replying again and again trying to pry these all critical pieces of information from you in increments. Without them we cannot even guess what you did wrong.
Okay. First off, that I possibly fried the level shifter, indeed taught me a lesson, after all I figured out what I did after reading the specs. Not totally dumb.
Second off, I am curious as to limitations, wiring and discussion for and against the use of optocouplers.
I thought this was clear from the first post.
As to wiring, the reason for asking is that I dont know precisely how to wire up a bidirectional line with optocouplers. My "probem" is that I don't get convinced that it is futile, just from being told in bold font by a single agitated individual, that my question is wrong, even though he has 10K postings.
Being told that I haven't understood anything and are grasping at straws ... what is that? I am curious to learn, not desperate. I have many options available to me, including clocking down and running on lower voltage, so that I don't need a level shifter.
What instructions am I not following? That of not explaining sufficiently what my needs are? Of not accepting the "common GND" response as complete and all-encompassing when coming to the use of optocouplers?
What I am doing is searching for things I know not too much about. I should probably have tagged my initial request as "curious about optocouplers" and never mentioned the litte aside about how I fried my level-shifter, as that was anecdotal only.
I see that I have not been too clear on my intentions, but even as those are explained by me, you still feel your task being to pry information from me in small increments. What do you want, a diagram showing how I2C is wired?? I don't really know what more there is to say than the following:
Pros and cons, technical and programming considerations using optocouplers for SCK and SDA-line of I2C hookup between components of different voltage.
There it is, but obviously you need some more details from me, about my reason for thinking this, and whether I fried my levelshifter with 5V or not, and perhaps even humbling myself some more as to how stupid that was, blah blah?
We clearly don't understand each other.