Originally Posted by jerber According to the datasheet they can handle a pulsewidth of approximately 200 nS,... |
I think the datasheet is times are when the input signal is a nice buffered 5V signal.
The signal from the parallel port will typically be a little over 3V, with a lot of
capacitance from the parallel port leads. Alan's circuit was designed so a separate PC side power supply was not required, so he couldn't buffer the inputs. I have attached a trace of an opto output during stepping.
I think this was a 7 or 8uS pulse width.
As you can see, the signal is still pretty low at 2-3uS.