Digital Read with 4N35 Optocoupler

Projects General Guidance
21

OK, I got curious and am trying to untangle this mess.
It's worse than I though - seriously, Fritzing is terrible.
There are two resistors marked R10, two resistors marked R14. These annotations should be unique (doesn't Fritzing do this for you?)
I found a Vss connection, the line goes into the NodeMCU, I guess to GND, but as it overlaps(!!) the symbol itself this is ambiguous.
SCL and SDA are connected to each other, and the resistors R13 and R12 are in the lines, rather than acting as pull-ups. The way it's drawn it can't work.
The way that barrel jack (is it?) connector connects to the optocoupler just doesn't make sense at all.
This is your circuit, drawn in a much more readable way (with the SCL/SDA lines untangled):

schematic.png
schematic.png952×404 6.99 KB

As is now quickly clear, this can't work. It's impossible that this is your actual circuit.

22

joshbg2k:
Haha, yeah sorry about that. I mostly use Fritzing to create PCBs. In practice SDA1 and SDA2 are not both connected to the same optocoupler,

If you want help getting a circuit to work you have to provide an ACTUAL diagram, of the circuit that you designed and built. Not something different. That's a waste of time.