I want to read 230V/50Hz line voltage input signals with an ESP8266. Please have a look at my schematic, I chose an opto-isolator with AC input (LTV-354T) and added a simple RC filter to keep the digital input at low level during the zero crossing:
I simulated the filter with LT spice and noticed that the output signal has a long rise time (approximately 10ms):
My question: Should I add a schmitt trigger/buffer?
The ESP's datasheet doesn't reveal much about its input stage, maybe the chip already has schmitt inputs?
Another (additional) question, I hope this is allowed: What is the lowest input/LED current you would recommend?
The current circuit drives the opto isolator's LED with 1,6mA. I'd like to lower the power consumption and heat dissipated by the resistors.