I am trying to read a speed signal from a tractors transmission control unit. Its 3.3v and 1-2khz pulse. I'd like to optocouple it and have a few 4n37 available.
As I really dont want to screw up the vehicle electronics I'd like to verify what I am planning to do.
The 4n37 needs a forward current of 10ma so I'll put a 220 ohm resistor in series there.
On the arduino side can I just use the internal pull up resistor and nothing else to read the opto?
Is the 4n37 fast enough? Turn on/off time is <10us so I am thinking it will be fine.
Anything else I need to watch for?
As I really dont want to screw up the vehicle electronics I'd like to verify what I am planning to do.
The 4n37 needs a forward current of 10ma so I'll put a 220 ohm resistor in series there.
On the arduino side can I just use the internal pull up resistor and nothing else to read the opto?
Is the 4n37 fast enough? Turn on/off time is <10us so I am thinking it will be fine.
Anything else I need to watch for?