Am 14.11.2013 um 21:10 schrieb Maximiliano Fermín Córdoba <[email protected]>:
> My main goal is to test the beaglebone with linuxcnc in the worst escenario > so as to decide if it is capable of managing the whole system operation. > Maybe the best option is to use an external stepgenerator and use the 'bone > only for the graphical interface and the gcode interpreter. Something like > sending through spi (or something like that) the actual movement and the > external embedded system drive the steppers. That would be solving the wrong problem IMO. Timing with the PRU code is not an issue, as is main CPU load wrt stepgen, and things likely will get worse if you shift to something like the picnc which was done only because the Raspberry just doesnt have the bang to do software stepping. You might break even again if you do something in the Mesanet card league - FPGA's doing the heavy lifting; which is a bit the tail wagging the dog right now. I think the only relevant parameter here is if the jitter (50-70uS on Xenomai/Beaglebone) has any impact on position accuracy. I think its rather irrelevant for stepper systems at least. But do the math yourself - look at pages 20ff of http://static.mah.priv.at/public/portable-realtime-API-talk/osadl-rtapi.pdf and see what this means for the speeds you are looking at. -- I think overall we're heading in a different direction - (at least my) plan is to separate UI- and non-RT related tasks from the RT environment and link those over network, and this effort is making good progress. I think we'll have something to show end of the year and something testable in Q1. For now you might want to take a lower-overhead UI than Axis which might go a long way. Hopefully we get OpenGL hardware support going, that's being worked on and might bring some relief. > So my actual drivers are driven with 2usec pulses and I was willing to > generate reliable signals with a max frecuency of 50k. If the jitter is > like the one Im facing now its useless. I think Peter explained this already - stepgens work as discrete frequency generators, not continuous, and you will see discontinuities with pretty much any implementation of this sort, so this is systematic and not an implemtation artefact not sure a scope image is a solid foundation to declare this method useless - Michael > > I would really appreciatte your guidance in configuring properly my system. > > Thanks > > Maxi >> -- >> Charles Steinkuehler >> [email protected] >> >> > ------------------------------------------------------------------------------ >> DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps >> OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access >> Free app hosting. Or install the open source package on any LAMP server. >> Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native! >> > http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ > DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps > OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access > Free app hosting. Or install the open source package on any LAMP server. > Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native! > http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access Free app hosting. Or install the open source package on any LAMP server. Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native! http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
