Chris Radek wrote: > It's up to the driver to figure out how to make a good velocity > output. As you say, if the driver doesn't do this, you can use ddt or > a delta debug output, but it won't be index-safe. Seb put a lot of > effort into the velocity output of the new mesa drivers lately, and > they are index-safe. It would be nice if the ppmc encoders had this > feature too.
Ugh, i had intended to clean up my documentation of the hm2 encoder algorithm and add it to CVS, but somehow (surprise!) that task keeps getting bumped down the todo list... Here's the rough notes (in need of cleanup & organizing!), in case it's useful: <http://highlab.com/~seb/emc2/hm2-encoder/> Note, however, that the index-safety issue is not addressed in those scribblings. Most of the complexity of the hm2 encoder velocity code is in dealing with rollovers of the FPGA's timestamp register. The hm2 driver uses "latch count on Index"; it tracks both "absolute counts since power-on" and "latched count at previous user-requested Index". Velocity is computed using the former, position is computed using the latter. -- Sebastian Kuzminsky All my desires and ruminations are no more and no less than eddy currents generated by the gradual exhalation of our universe. And until this great exhalation is finished, my thoughts live on. <http://tinyurl.com/c2t5rb> ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
