Re: New project...PCI based servo control board

[Jon Elson <elson-at-pico-systems.com>]

alex wrote:

>Folks!
>I know nothing of FPGA.
>But why , if we are talking of ISA bus, not to use a standart C to write and
>compile an application?
>
The whole problem, at the beginning, is that software generated step pulses
are not regular enough, or can not be ramped up and down in rate smoothly
enough, for some stepper motor applications.  Replacing a x00 MHz Pentium
with a PIC is not going to solve this problem.  For instance, I have a 
product that
produces step pulses up to 300,000 per second, per axis, with a timing 
resolution
of 100 nS.  So, even at 300K steps/sec, the granularity to the next 
faster or slower
speed is only 3.3%.  (The FPGA is loafing at this rate, if you needed 
more, the
clock could be turned up.)

Depending on the algorithm, software generated step pulses may have 
granularity
of 25% or so at these rates.

It can get worse if you want to have encoder feedback of actual 
position, too.

Jon

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