Re: PC based CNC system architecture

Hi,

I've e-mailed preliminary circuit diagrams and a tentative form-
factor 3D renderings to a few people. I will post to "Files" this
weekend my work to date.

The wise advice I've gotten is to have the port "polled" rather than
interrupt. This requires a buffer on the pulse generator. I am
looking at using a "Rabitt 2000" microcomputer. It is cheap, small
and capable ($29, 1.9" by 2.2", 256K Flash, 128K SRAM, 40 I/O lines,
20MHz and Z80 superset instructions).

The pulse generator layout is well along. It will have jumpers for
full-step, half-step and 10 microstep drive types. There will be
jumpers to set the full scale speed range of 4096, 8192, 16384 and
32768 equivalent full steps per second speeds.

What that means is if the jumpers are set to 16384, then speeds will
be in order:

0) 0 Hz for FS drives, 0 Hz for HS drives, 0 Hz for 10 uS drives
1) .25 Hz "", 0.50 Hz "", 2.5 Hz ""
2) .50 Hz "", 1.00 Hz "", 5.0 Hz ""
3) .75 Hz "", 1.50 Hz "", 7.5 Hz ""
.
.
.
.
32765) 32,767.25 Hz "", 65,534.50 Hz "", 327,672.50 Hz ""
32766) 32,767.50 Hz "", 65,535.00 Hz "", 327,675.00 Hz ""
32767) 32,767.75 Hz "", 65,535.50 Hz "", 327,677.50 Hz ""

Note the even spacing.

Mariss

--- In CAD_CAM_EDM_DRO@egroups.com, "Wally K" <cnc4me@u...> wrote:
> Mike, i think the problems with Jons soultion for EMC and stepper
> control is as follows.
>
> Jon please correct me if i am wrong.
>
> 1) It is a closed proprietary system.
> 2) Jon is building what he wants with no input from the group.
> 3) it will be fairly expensive. From memory $350.00 or so.
>
> Wally K.