Re: [CAD_CAM_EDM_DRO] Re: The mechanical part of my router is done!

Chuck,
What you did is right and having the 555 is a benefit for testing purposes.
Add a switch to cut in as needed.
Why the L297-298 may not perform:
Test for a 3.5 micro-sec neg going pulse at pin 1 (L297) at ~18 KHz.
If not there, the oscillator is not working. See R21 and C5 for the timing components.
RichD

Charles Knight wrote:

>
> OK, guys...I need a little bit of help. Who's good with electronics?
>
> I have bought 3 stepper controller boards -- they are based on the
> L297/298 chipset, and run my motors very nicely. The down side is that
> they have an on-board pulse generator -- no hookup for a parallel port.
> Which means...modifications!
>
> Here's the schematic for the board -- it's a surplus board from TI.
> http://makeashorterlink.com/?V59F32F45
>
> As I see it, I need to bypass the 555...cut the lead between pin3 on
> the 555 and pin 17 on the 297, which is step input. And I need to hook
> into pin 18 on the 297, which is direction. Of course it didn't work
> like this, which is why I'm asking for help.
>
> Assume nothing -- I've played with serial ports, but I'm not sure about
> parallel interfaces -- does anything need to be tied to ground, a state
> or enable pin tied such that it is active, etc?
>
> Now, all of this, I can do (though maybe with some help from you
> guys)...is there any real danger of blowing something out? I live in a
> TINY town, and having to build a breakout board, or something similar,
> would add in a week's delay, just because of the unavailability of parts
> in this area. To be honest with you all, I just want to see my motors
> spin under computer control! Down and dirty hacks are fine, at this
> stage of the game.
>
> HELP?!
>
> -- Chuck Knight
>