I have a 3.3v microprocessor on the same board as a few other components all 3.3v and I'm wanting to connect the 3.3v systems GND to the GND of a 5v system with it's own 5v components.@super7800Thank you for your answer! My board is getting power from an external 5v system so I used the quick and cheap method of using a resistor pair to shift the level down from 5v to 3.3v. The external system providing the 5v power also provides a ground that I directly connect my 3.3v system GND to as-is (making path of least resistance, hence no level shifters or protection from a 5v system)So there is only 1 positive point (level shifted) and one negative point (unprotected) in/out and I'm gathering from your post it's A-OK because despite the voltage differences between the two systems, connecting the two GND is fine as long as theirs not two different sources of power which, in my case, theirs not, only one and it's coming from the 5v system.@DrDiettrichjust saw your post and missed it in my initial reply, sorry. I'll keep it in mind to try before assuming it's safe. Thank you.
how do I do I convert ~22 pins (excluding ground and output-only lines) to 3.3v on a tiny cramped pcb and keep it low cost.
Using resistors to divide supply voltage down is not good.
How would you recommend I lower the voltage then, I'm fairly new to electronics.The issue is I have 32 pins I'm interfacing with and all are to a 5v system. The supply and RST is 5v and the data lines in and out are all 5v based TTL. The solution I need to use is also on a tiny PCB board that's somewhat cramped.If resistors is a bad way to do this then how do I do I convert ~22 pins (excluding ground and output-only lines) to 3.3v on a tiny cramped pcb and keep it low cost.I've seen some other solutions but I'm not sure what else to use, if you have better feedback or suggestions I would greatly appreciate feedback on this as it's been a huge problem I'm trying to figure out.
Currently my resistor pairs are 1K and 2K. Should I do something else?
I drew that out that days or weeks before I posted this question.