I'm just finishing up the design for an A3977SED based controller board but I'm a bit confused about the parallel port connections. Can the parallel port drive logic high and low or does it just go active low (sinking) and high-Z? i.e. Do I need pullups to generate logic high, or can the parallel port handle this just fine? I plan on pulling Enable high on the board and setting it to active low in the software. That way if the cable pops out I know the drives will stop.
Message
CNC controller - port pin pullups/downs?
2003-10-12 by ghidera2000