On 12/27/2018 1:59 PM, Juha Heikkila wrote: > Hello, > > I have been trying to search if the SPI could be read within the > base-thread. I'm trying to achieve a fully closed servo loop for 5-axis. So > I would have 5 x step/dir outputs and 5 x quadrature encoder inputs. > > I would like to use BBB as a base and build from there, I will run out of > IO and would like to offload the encoders to a dedicated counter IC or an > FPGA. So then I need a link between either one of those an the BBB and SPI > would work IF it can be read in the base-thread. > > Any other options would be more than welcome as well.
One of the SoC+FPGA boards would work much better than a BBB for 5 axis of closed-loop servo control. Or any low-end PC with a Mesa card if you want good native graphics. The BBB only has 3 hardware encoder inputs, and it's difficult to use all of them without sacrificing something else. The PRU PWM also isn't really fast enough for closed loop servo control, so you'll need to use hardware PWM as well (I'm not sure how you intend to use step/dir to drive a true servo motor). You're really much better off with an FPGA. -- Charles Steinkuehler [email protected] -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
