Re: [CAD_CAM_EDM_DRO] Re: USB on Linux

Les Newell wrote:

> There are lots of microcontrollers out there that have everything on board,
> for less than the cost of an FPGA. However I suppose I could be considered
> biased as I spend most of my working life dealing with microcontrollers..

Yes. Well, there are both pros and cons. The interaction between several
different pieces of software, running on separate processors, can get
quite hairy. Throw in real time response, and it gets worse. The reason
I went with non-processor based peripherals was that timely response
was GUARANTEED! The entire servo loop, from reading the encoder
counter, processing the PID parameters to calculate the new velocity
command and putting the value into the DAC, all takes place within
50 uS, for 3 axes on a 333 MHz Pentium. If there were microcontrollers
in the works, that would not be easy to do. I also have doubts about
software-driven encoder counting. I prefer to do it in dedicated hardware,
so that I can be certain counts are never missed.

Jon