John Kasunich wrote: > Sebastian Kuzminsky wrote: >> John Kasunich wrote: >> What's a use case where it's valuable to read/write the modules separately? > > Mostly something like the arrangement Kirk Wallace has - software > stepping, using the GPIO for the step pulses. You might ask "why do > software stepping when there is hardware stepping available?" In many > cases that is a darned good question, but in Kirk's case, I don't think > the existing firmwares supported hardware stepping. > > There is also the case where you need one more channel of stepping, or > encoder counting, or whatever, and you don't necessarily need the full > hardware performance. For example, the Mazak at the CNC workshop uses a > 4-channel Motenc board. Three encoder channels are used for X, Y, and > Z, and the fourth is used to count the spindle encoder for spindle > orient and rigid tapping. We used a software encoder counter and two > GPIO pins for the jogwheel, since it doesn't spin fast enough to require > hardware counting.
Heh, the way to do that with HostMot2 is to email Peter and ask for a new firmware image with an extra stepgen and encoder. :-) Or just change a couple of constants at the top of the VHDL and compile it yourself (assuming you have enough gates & pins). The new VHDL source (not in CVS yet) makes this kind of tweaking really easy. >> I believe it's fine to share the EPP bus between RTAI threads, because I >> believe RTAI threads (at least as used by HAL) are not pre-emptable. Isn't >> that true? > > Not true. Threads are interruptable, based on priority. Fast threads > are higher priority than slow ones, under the assumption that the code > in a 1mS thread might take 200uS to execute, and a 25uS thread might > need to interrupt it and run a few uS worth of code several times. That make sense. I stand corrected. -- Sebastian Kuzminsky You think you can defeat me with your rebellious beard? <http://www.youtube.com/watch?v=k_QAPjtO2cA> ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
