I need to find the start of this thread. i am running a G540, an Intel M525MW board with Probotix steppers motors and all 3 axes move fine. I just need to calibrate them for proper distance and get the homing Hall effect sensors connected.I am not running the charge pump enabled in the G540. Am I missing something?
Gary K8IZ On 4/15/2012 8:38 PM, Kirk Wallace wrote: > On Sun, 2012-04-15 at 21:37 -0400, gene heskett wrote: > ... snip >> What happens if the pump frequency is reduced to say 10% of what its set at >> now? > I haven't tried that. If I disconnect the G540 so there is no load on > the parallel port pin, the charge pump is a clean square wave. I used > 10x on the probe, if that makes a difference (I know just enough > scopenese to get by). > >> Looking at the scope traces, either the probe is way out of calibration >> against the scopes own test square wave, or the 540 has a low value series >> resistor, 33-120 ohm range, with several hundred pf on the other side of >> the resistor as a noise filter on that input, and likely on all inputs >> since engineers have a tendency to 'step& repeat' for that stuff. > I tried to trace the traces on the G540. From the pump input wire > terminal, the trace goes right to an unmarked SMT capacitor. The other > side goes to the center of a three pin SMT something-or-other. My guess > is it is a transistor, maybe. Another of the three pins goes to the > opto-isolator. I gave up tracing at that point. > >> I can't believe you would long tolerate a probe that far out of adjustment >> Kirk, so that leaves the 540 apparently suffering from way too much noise >> filtering on that input. So the pumping frequency is so high the capacitor >> used for noise filtering never has a chance to either fully charge, or to >> fully discharge. So you get insufficient swing. > The G540 manual specs a 10kHz minimum, so the filter doesn't need to > pass the low end. The large C is a bit of a mystery so far. One thing > that stands out to me is the rising edge is near vertical until about 2 > Volts then dog legs up. I expected to have a continuous smooth curve > from O Volts until 5 Volts or when the pin switches. > >> So drop the pump frequency to 10-20% of what it is now just for effects, >> would be my advice. If it drops out because the pump is then too slow, the >> 540 needs a redesign tweak, at least according to Gene. :) >> >> Cheers, Gene > My favorite fix so far is to recomend a buffer board on the parallel > port. It's the only thing a user could add that would cover most every > parallel port and the G540. A user would have a harder time fixing the > G540 or the port. I need to find a loose buffer card around here and try > that next. While I'm at it I'll check too see what happens with a slower > pump. > > -- Gary Fiber K8IZ GROL PG-19-6691 with shipboard radar endorsement Washington State resident ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
