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Home Forum General General LinuxCNC Questions No step pulse output from parallel port

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TOPIC: No step pulse output from parallel port

Re:No step pulse output from parallel port 04 Apr 2012 02:13 #18960

  • cncbasher
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to test your hardware , with the controller connected up and power on , you should find that the stepper motor shaft is unable to be turned , i.e locked up
if the shaft can be turned then you have a fault .

if the above is correct and the shaft is locked up , then pulsing the step pin to ground ( i.e like tapping on a morse key ) you should have the stepper motor moving one step at a time as you pulse the input pin
the direction pin is either held at 5v or 0v to then reverse the stepper motor .

in the wicki their is a parrell port test application that may help , in a similar way as is described above

did you use step config to produce your parrell port config file ?
selecting the default configuration should work fine for your board
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Re:No step pulse output from parallel port 10 Apr 2012 11:37 #19107

Great info. THANKS!
I've found several issues regarding my driver board that have to be solved before any testing is possible. My counter IC's do not consequently count and the decoder IC's are not decoders due to a wrong subsitution by my supplier:unsure:
If correction of these subjects do not solve the problems, I'll go back to your test procedure.

I did use stepconf to set up the configuration. I believe the pin settings are not correct in any of the standard setups as my board have an "enable" input pin for each axis, but maybe I can use the same timing settings!?

Rgds
Peter
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Re:No step pulse output from parallel port 11 Apr 2012 00:34 #19123

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it's not required to use the enable , just make it permanantly enabled to start with , the enable for each axis can be tied to one pin later if needed ( i.e amplifier enable )
the default timing set up in stepconf should be fine for the boards you have , and initial testing
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Re:No step pulse output from parallel port 18 Apr 2012 22:34 #19367

OK I think I get you. I can use the timing settings but of course I still need to set up the pins according to my driver board. Thanks again.
Rgds Peter
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Re:No step pulse output from parallel port 30 Apr 2012 13:09 #19673

  • submicro
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I couldn't get step pulses from mine either, I tried everything!!!. Turned out I had the wrong kind of DB25 cable. All cables are not created equal!
Just my 2 cents. hope it helps.

SubMicro
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Re:No step pulse output from parallel port 01 Mai 2012 04:51 #19705

  • andypugh
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skarnsungen wrote:
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???

I missed this first time round, but there are a couple of things worth noting here.

The way that Stepconf configures a stepgen by default is to use the Parallel Port "Reset" function. This means that the step pins are set high when required, then at the end of all the base-thread activity the Reset function is called, which waits for the requested time and then sets the selected pins back to low.
The reset time is set to the step-length timing, normally a few microseconds.

Note, however, that the reset function stops everything dead waiting for the reset time to elapse. if Step-len is longer than the base thread period then the computer will lock up completely. (Actually, I rather hope there are safeguards in place to prevent that)

You _can_ set up to have extremely long step times by manually editing the HAL file to remove the "reset" function.
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