El 14/11/2013 13:18, "Charles Steinkuehler" <[email protected]> escribió: > > On 11/14/2013 8:11 AM, Maximiliano Fermín Córdoba wrote: > > HI > > > > I´m trying to modify the BeBoPr-Bridge.ini file, but I get stuck when I saw > > that the steps timing config was already OK for me. (I need pulses of 1useg > > and 1useg minimum distance between each other) > > > > The thing is that I´m seeing step pulses of 10usec width, but the config is > > set to 1useg ([...] STEPLEN 1000 in nanoseconds [...]). > > > > Is this an issue of the minimum step pulse possible ? > > By default, the PRU thread is running with a 10 uS period, so that is > the minimum time any pulse can be made high or low. The 1000 nS pulse > width is a *MINIMUM* time, so the pulse length will be at least that > long, but possibly longer. > > > Also, an error come out saying : "hpg: stepgen.00.maxvel is too big for > > current step timings & position-scale, clipping to max possible". Has this > > something to do with my issue? > > This is due to trying to generate too many pulses per second. You > mention a 5000 mm/s feed (which is *VERY* fast), but what is the pulse > rate you are trying to generate (or the steps per mm for your machine)? >
I'm trying to move at 5000mm/min not seconds... My steps to mm factor is almost 500.. I mean it takes 500 steps to advance 1mm. So this gives me a rate of 41khz. When I generated this type of movement the signal generated had jitter above 10usec. > With the default 10 uS PRU task period the maximum theoretical pulse > rate is 50 KHz, but I wouldn't recommend going much over 30-40 KHz in > actual use (or even lower, depending on your particular servo drives and > their sensitivity to jitter). The 10 uS period for the PRU is a *VERY* > safe value, it can easily be dialed down if you need faster step rates. > Alternately, it is possible to offload a few very fast dedicated > step/dir generators to the second PRU and get the task period below 1 > uS, but I haven't written code for this yet. > > Let us know what rates you need to hit and I'll advise you on the best > way to get there. > 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. 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 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
