Re: cheap retrofit with the Allegro UCN5804B chip

Henk Verschuren
 

Hi Walt,

Now I think you donĀ“t need a UCN5804B at all.
Checking out this project: www.stmental.net/~dfoster/emco I must conclude that the EMC2 software is capable of generating "A B" signals through the parallel printer port. These guys made a simple circuit that inverts these signals so now they have "A B !A !B" signals that can be connected directly to the stepper board.

You would only need a UCN5804B (or a self programmed micro controller) if the software can only generate Step/Dir signals.

Kind regards,
Henk



--- In Emco_cnc_users@..., "cncwannabe" wrote:
>
> Thanks Henk. That's good to know. I was too lazy to drag the control unit away from the wall and check.
>
> I would put the UCN5804B right at the connector because I think the circuit is at risk to be noise sensitive. I also think opto isolated step and direction signals would be required.
>
> I was surprised how expensive the UCN5804B is on Ebay. I think I'll post a schematic of how this function can be done with discrete logic.
>
> Best regards,
> Walt
>
>
> --- In Emco_cnc_users@..., "c5cnc" wrote:
> >
> > Hi Walt,
> >
> > The ABCD inputs of the stepper board go directly to an onboard 74LS38.
> > So there are no pull-up nor pull-down resistors.
> > Therefor a UCN5804B can be connected directly to the stepper board,
> > although you could consider decoupling with opto-couplers.
> >
> > Kind regards,
> > Henk
> >
> >
> > --- In Emco_cnc_users@..., "cncwannabe" wrote:
> > >
> > >
> > >
> > >
> > > Peter,
> > >
> > > You should be able to find schematics in the files section of this or
> > the F1 group. I'll summarize what you will find.
> > >
> > > There is a six pin connector for each axis on the F1 Stepmotor board.
> > They are designated X34, X35, and X36. The pin #'s and labels for each
> > axis are:
> > >
> > > Pin Signal
> > > 1 5V
> > > 2 GND
> > > 3 C
> > > 4 D
> > > 5 A
> > > 6 B
> > >
> > > The ABCD signals match the UCN5804B data sheet.
> > >
> > > You may need to add 5V pull-up resistors to the outputs of the
> > UCN5804B. I don't know if the Stepmotor board provides them. Hopefully
> > it doesn't have pull-downs. You may also need to provide an
> > intermediate buffer (CMOS inverters would do) to provide some noise
> > margin due to the Darlington transistor outputs of the Allegro part.
> > You want the logic zero output to be well below 0.8V.
> > >
> > > The EMCO system uses the "two-phase drive sequence" described in the
> > data sheet.
> > >
> > > Good luck with your conversion.
> > >
> > > Walt
> > >
> > >
> > >
> > >
> > > --- In Emco_cnc_users@..., "keizer.peter" wrote:
> > > >
> > > > Hi guys,
> > > > While searching for a cheap (an temporary) way to retrofit my F1
> > (and
> > > > maybe also the 5CNC) machines i found this old message here on the
> > > > beard:
> > > > "Hi
> > > > Funny, this seems to be the first post :)
> > > > A little background on my experiences.Okay, I own a F1 CNC mill for
> > > > about four years now.The native programming for the F1 is in a word
> > > > SUX.So, I look around and found the company WelSoft,its
> > > > www.welsoft.co.uk and looked at their Wellmillconversion board.
> > Simple
> > > > thing methinks, butgodalmighty aint they expensive!!!So, I do a
> > little
> > > > research on the way the wellmillconnected to the emco. Having a
> > circuit
> > > > diagram forthe F1 helps a lot :)
> > > > Lo and behold, I came up with a design that worksfor the past 3
> > years.
> > > > I use Allegro's UCN5804B chips for step/dir control,TurboCNC from
> > DAK
> > > > engineering for the Gcode to Step/dir translator,DeskProto for STL
> > to
> > > > GCODE translator andSolidworks for design.
> > > > If anyone need some help...
> > > > Gelandangan."
> > > > I have searched in google, i have read basically every message up
> > here
> > > > and also the EmcoF1Mill group.But i couldn't find any good
> > explanation
> > > > of how to do this.
> > > > It seems that it's possible to actually use the Emco stepdriver
> > board
> > > > and the original drivers.Then you just hook up the machine to your
> > pc
> > > > and use it with Mach3 or whatever and use it like that.
> > > > Is there anyone that knows how it works or can be done?
> > > > I've already ordered 3 of those chips on ebay, since they're very
> > > > cheap.I wasn't sure whether i needed 1 chip per axis, or one chip
> > per
> > > > machine.
> > > > I hope one of you guys can help me out!
> > > > Thanks a lot in advance!
> > > > Peter Keizer.
> > > > (I'll be posting this same question in the EmcoF1Mill group.If we
> > can
> > > > figure out how it works, i'll make a nice tutorial of it so others
> > can
> > > > do it as well.)
> > > >
> > >
> >
>

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