Charles Steinkuehler wrote: > On 10/11/2013 5:22 AM, andy pugh wrote: > >> I don't think an EPP interface out of the BBB and into the 7i43 makes >> much sense. The 7i43 takes commands from the EPP and produces step/dir >> and/or PWM and/or GPIO signals from that. >> This means that a BBB to EPP interface would probably be using the PRU >> to prestend to be an EPP parallel port to tell a 7i43 to do exactly >> what the PRU _already_does_ . >> > > The point is not to use the 7i43 for step/dir generation, but for true > servos with encoder feedback. This is _maybe_ possible using just the > BBB and the PRU, but using something like the 7i43 means a lot less > development work. Yes, exactly. Something I really want to do is create PRU code and hack my PPMC driver to talk through the PRU for fast access to the external device. Later I might create firmware for these devices with streamlined I/O to allow faster servo cycles. The PRU is great for step generation, but when faced with having to sample multiple hardware encoders at high speeds as well as create PWM or analog outputs with high resolution, it runs out of gas.
Jon ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60134071&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
