hey
I have accidentally used an Opto-isolator(LTV-8241S) with an Vce sat of 0.8-1V. And connected it directly to the MCU with an 2k2 pullup to 3.3V
The MCU has an lower threshold of 0.825 to detect an digital Low input.
The opto-isolator was selected because of its really high RTC 600% and is used on line voltage (230Vrms) with 2x100k input resistor (400V 1206 SMD).
Since the PCB is already soldered there is no possibility to make big changes.
What would be the simplest solution to get the voltage down and make the detection more reliable? There is enough space to add an sot-23 package with dead-bug soldering.
I was thinking of mis-using an mcp100 as an 3pin comparator.... but maybe an 2N7002 is enough