Sebastian Kuzminsky wrote: > EPP mode is a completely different way of using the pins of the parport than > the regular SPP mode. In SPP, you have programmatic control over the values > on the output pins, and you can read all the input pins. > > In EPP, those pins are driven by an additional piece of logic in the parport > controller. The driver software asks the EPP controller to read and write > addresses on the EPP bus, and the controller twiddles the pins to implement > the software's request, according to the datalink protocol described by the > EPP spec. So in order to do anything interesting/useful with the EPP port, > you need a second driver that knows what registers to read and write on the > device on the EPP bus. > > Simply switching the port to EPP mode doesn't accomplish anything. > Not completely true. In EPP mode, a number of the signals are driven both sourcing/sinking, there are some pull-up turned on, but the basic SPP/Bidir port functions will still work, without invoking the EPP handshaking modes. For the G540, this pullup or output driver characteristic seems to be the thing that matters. The handshaking becomes active when the PC accesses the additional EPP registers above the traditional 3 SPP registers.
Jon ------------------------------------------------------------------------------ Better than sec? Nothing is better than sec when it comes to monitoring Big Data applications. Try Boundary one-second resolution app monitoring today. Free. http://p.sf.net/sfu/Boundary-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
