No step pulse output from parallel port

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03 Apr 2012 13:34 #18944 by skarnsungen
Hi folks. Please help a EMC2/Ubuntu newbie...

Finished my EMC2 installation a couple of days ago and since then I've taken the first small steps into the fascinating world of EMC2. I think I've managed to set up a bootable configuraition with stepconf. But now I'm STUCK!
I'm getting no step output on the X, Y and Z step pins. The direction output works fine. I'm testing with a LED+resistor between pin 25 (GND) and the various output pins. I get a dim light shifting on the direction pins.

What I've tried regarding the step pins is:
-Set step pins to "inverted". The light comes on, at the corresponding pin and thus I suppose the parallel port is OK !?
-Measured voltage om the pins when moving position manually in the software. Result is unclear, I get seemingly systematic fluctuations but only around 25 mV in magnitude. Absolutely not sure I'm having any pulse activity!
-I've tried various settings of timing including the slowest possible settings of 0,5 sec
-I found a similar topic in this forum, mentioning the possibility of monitoring the pin values in the Hal-meter, but in my case this is not helpful as the window minimize everytime a setting is changed.

So any input is appreciated - how do I figure out what I'm doing wrong?

Thanks in advance
Peter

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03 Apr 2012 16:59 #18947 by BigJohnT
Step pulses happen pretty fast and you may not be able to see an led light up. The fact that you can see the direction pin change states is a good indication things are well. Do you have a driver or are you just experimenting with leds?

John

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03 Apr 2012 17:33 #18948 by skarnsungen
Hi John
Thanks for your reply.
I do have a kind of driver. It's a homemade DIY design by Tom at: www.instructables.com/file/F5LOYU4F5R8QRL0. No timing info is supplied thoug. I've finished building the driver but when testing according to the mentioned procedure I do not get the supposed level-shifts on the IC pins - not even the input pins.
I'm now sure that there is some activity at the step pins as I can better registrer the voltage shift after raising the timing. You say that stepping happen very fast, but I thougth it was as simle as when I set step -timing and step space to 500000 ns I would get at pulse lasting 0,5 sec every 0,5 sec. Probably wrong???

As I'm now very much in doubt if I-m having a EMC2/ computer parport issue or the driver is the problem, Is there some way to find out? (other than buying a well tested commercial driver)

Kind regards
Peter

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03 Apr 2012 19:03 #18949 by PCW
500000 nS is still just .5 Milliseconds...

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03 Apr 2012 19:41 #18950 by arch dude
If you do not have an O-scope, you can choose to build a trivial latch. Alternatively, you can learn enough about HAL to "build" a counter on an input pin and then connect your (physical) output pin to the (physical) input pin. You may also be able to use the HAL O-scope on the input pin: I have not tried this myself.

If you trust the software, you could simply use the HAL O-scope on the output pin.

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04 Apr 2012 05:51 #18957 by skarnsungen
Thanks!!
Messed up the suffixes quite badly. :silly: Of course 500000 ns is just 5 ms an not 0,5 s.
I do not have a scope and as mentioned I've not been able to use the HAL scope and I'm very far from beeing capable of understanding or editing HAL files myself.
I'm almost convinced that things are as suggested -that the time is just not long enougt to light up the LED, as I do see millivolt activity when jogging the axis. I'm going to dig a bit more in my controller function...
Kind regards
Peter

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