-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I'm new to LinuxCNC and have a few questions about hardware, and want to make sure I'm understanding things correctly before I start hacking.
It seems many folks are using a standard parallel port and driving step/dir signals (maybe even reading encoder pulses?). All well and good, but limited by the speed of the "fast thread" in terms of pulse frequency that can be generated (50 KHz is mentioned in the wiki). Enter something like the Mesa 7I43, which ties to the parallel port, but in EPP mode, and supports hardware generation of step/dir, PWM, encoder support, and much more. This seems like a great thing, but the comments in the HAL setup for a 7I43 indicate: <quote "configs/hm2-stepper/7i43-small.ini"> # Step timing is 40 us steplen + 40 us stepspace # That gives 80 us step period = 12.5 KHz step freq # # Bah, even software stepping can handle that, hm2 doesnt buy you much with # such slow steppers. # </quote> Questions: 1) Why is the step rate so low on the 7I43? I don't see any direct reason in the hm2 HDL design, the LinuxCNC software, or the EPP port limitations that should require this low step rate. What am I missing? 2) Has anyone tried an intermediate solution between a plain parallel port and an FPGA hardware solution? I'm thinking about something like a cheap micro-controller programmed to talk to the EPP port and use it's built-in timers for step pulse generation (ie: take an Arduino or similar like folks are driving RepRaps with, and use it as a pulse generator for LinuxCNC). - -- Charles Steinkuehler char...@steinkuehler.net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk+DbugACgkQLywbqEHdNFxW7wCgypr9qnz9NpbrxDf/MkDovbwA Fa0AoMdTD9mQNNJZQmOpg968WJwG0H68 =ynHY -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
