Hi Charles, I am studying the possibilities of having 3 axes with step/dir and encoder signals A/B/I to control servos. It's a shame about the eQEP1, I saw the pin overlapping too :(
I have followed your work with PRU's and I'll try by this way. I think it is possible to use the PRU0 for 9 encoder signals and PRU1 to step/dir, 6 signals, although I think it will not be compatible with Bebopr for example, but make my own interface board not think it was a problem. I have to study in depth the programming of PRU for encoders. I think you have something about this (PRU encoder program). Is it working properly? maximum frequency that you got reading? any problem if I want to read 3 encoders at time? Thanks a lot. El sábado, 1 de febrero de 2014, 1:02:31 (UTC+1), Charles Steinkuehler escribió: > This is a heads-up to anyone working on BeagleBone based interfaces for > LinuxCNC. I am working on code to support encoders on the BeagleBone, > allowing true servo operation (within limits). Encoders can be > supported on the BeagleBone via hardware or software (via the PRU). > > There are three hardware encoders on the BeagleBone: > > * eQEP2, on P8 pins 11, 12, 15, 16 > > * eQEP0, on P9 pins 25, 27, 41.1, 42.1 (BeagleBone Black only) > > * eQEP1, on P8 pins 31, 31, 33, 35 (conflicts with HDMI) > > The eQEP2 pins conflict with the typical BeBoPr step/dir pinout (re-used > by several CNC capes), but could be used if desired, since step/dir pins > from the PRU can be freely assigned. > > The eQEP0 pins do not conflict with the standard BeBoPr pinout, and > might make a good primary encoder input for the spindle or other > high-speed axis. > > Sadly, eQEP1 cannot be used without disabling HDMI. :( I don't > generally intend to run without a display, but I'll make sure the HAL > BeagleBone encoder logic will support all three hardware encoders if you > don't need a display. > > In addition to physical hardware support for encoders, it is possible to > support encoders via the PRU. I expect to be able to fairly easily > support up to 100 KHz or so count rates (25 KHz encoder A/B signals), > and may be able to go as much as 10x faster, depending on how complex > the PRU code becomes and how many channels are enabled. Regardless, the > encoder A/B/Index signals will need to be on direct PRU input pins. On > the BeagleBone Black, PRU0 has 9 direct inputs available on P9 (only 7 > for the BeagleBone White), meaning it would be possible to support 3 > encoders with index, or 4 plain encoders on the 'Black. > > Feel free to contact me directly if you are working on a design and are > concerned about your pinout. > > -- > Charles Steinkuehler > cha...@steinkuehler.net <javascript:> > > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
