looking at this PCI board mentioned by 'ihatewincnc' last night, it seems there's some facility to write a waveform to RAM (or to a small on-board FIFO) which is clocked out at a set rate.
if the 1ms servo thread could calculate 1000 iterations of the step waveform and put them in a memory buffer, the board could clock them out at 1 per uS, giving a very nice waveform
sure sounds like quite a job
yeah---I think you'd have to integrate the board driver with the waveform generator, losing flexibility in the process
if one of these boards fell into my hands I'd try to write it
you need a good scope
cool.. my AtMega is displaying date & time on the LCD
the board sounds like it would make a decent logic scope, for signals up to 2MHz or so
I mean, for sampling rates up to 2MHz
* alex_joni runs home..
see ya Alex
jepler - maybe the thig to do with one of those boards is to put several waveforms into it (if possible), and just vary the update rate
if it can be done on different channels independently
SWPadnos: it looks like there's only one "out" channel
oh - a single 32-bit in and a single 32-bit out register?
one timer for the input, one timer for the output, and one that can be used as an additional timer prescaler
that card would be better for stepgen anyway, sice it's PCI, and uses a single DWORD address, instead of several byte addresses on ISA
yeah, the good side is that you can set all 32 output bits with a single I/O
and PCI runs at 33 Mz, so the I/O should post faster than 1 uS
MHz, that is
yeah though I'm not sure that buys you a lot -- one parport is only 2 outs and one in, so what if it takes you from 20uS to 17uS...
true. and you don't even have to wait for the last one to finish
but Alex might be able to get to 5 uS instead of 6 on his Athlon system ;)
6µs? that fast?
yeah - he was just seeing how fast he could go. I'm not sure he had anything in the base thread, but the machine didn't crash :)
SWPadnos: it was a stepper
and it didn't quite go to 6, but 7.5 was OK
so base_thread had the usual stuff in it..
I suspect for an empty base thread one could go under 1 usec
or at least with stuff in there that takes less time than parport update
ah - ok (alex)