On 4/9/2012 9:17 PM, Jon Elson wrote: > 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 > > ge.net/lists/listinfo/emc-users > >
>>For the G540, this pullup or output driver characteristic seems to be the thing that matters. << Yes, apparently when the port is in ECP mode the voltage is not pulled up high enough for the charge pump output from the PC to be recognized by the G540. I think the G540 would benefit from from pull up resistors on the input lines. Dave ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
