Re: [CAD_CAM_EDM_DRO] Re: Smart/Dumb box again...

Alan Marconett KM6VV wrote:

> Hi Jon,
>
> thanks for the additional info on your boards.
>
> So it will cost about $700 to get 3 or 4 axis support? I like the ECP
> (IEEE-1284) interface! Sounds like great resolution, although if one
> just wants to run "open loop", then is the encoder board still
> necessary?

Yes. The computer sets the step rate with precision, but after a few
moments, it really has no idea exactly when the step pulses are actually
coming out. So, the only way to know how many steps have really been
issued is to count them. The step rate generator creates both step and
direction signals, as well as quadrature phase signals. these can be counted
by an encoder counter, as well as used to drive phase-input stepper drivers,
like on BOSS Brodgeport machines. I hope to work on this some more,
and see if I can get more channels into a chip by reducing timing resolution
a bit. (100 nS is probably way more than you need, anyway.)

> Looks more like you're targeting commercial systems, I was
> hoping to get in under $200 ($100?) for a 3 or 4 axis rate generator.

As I said, I also hope to redo this as a complete package on one board, which
will drastically lower the cost. He, he, then it will have a 160-pin PLCC!

> 84-lead PLCC's are not something I want to solder in, either!

Yeah, that's why I'm using the socket! Unfortunately, the 160-pin socket
is more expensive than the chip! (I'm hoping the price on these has come
down since I bought them a couple years ago.)

Jon