4N37 opto isolator question

[3v0]

I am using 4N37 opto isolators in a USB to RS485 design. The problem is that signals going through the 4N37s come out inverted.

If I put a 74HTC14 Hex inverting Schmitt trigger between the 4n37 and the RS485 driver it would fix my inversion problem and maybe clean up the signal a bit.

OR

The 4N37 input (internal LED) is sourced by a PIC output pin. I could move the pic output to the other side of the internal LED and use it to provide ground (sink it?). That would also fix the inversion.

What do you suggest.

3v0

 

[IanP]

The second option seems to be easier to realize as you don't need to use additional external inverter(s) ..

Maximum output current sunk by any I/O pin .......25 mA
Maximum output current sourced by any I/O pin ......25 mA

Regards,
IanP

 

[lizardk]

The second option.

LizardK