[Bdi4emc-help] RE:X-Axis Display Problems

Mon Nov 27 01:26:03 CET 2006

Hi Craig

On Sunday 26 November 2006 16:37, elnerdo at cox.net wrote:
> 20,000 counts per revolution is in fact pretty high for an encoder. The
> "latest thing" however is the new sin/cos encoders which output counts in
> the millions.

The sin/cos encoder referred to in the article only has 1024 "periods" per 
rev. The sine waves are then interpolated to produce the 4M discrete counts 
with the aid of a dedicated DSP - Presumably, correction tables are 
programmed in to reduce cyclic errors and phase variations.

> I originally thought the video card might be the problem source so I
> replaced it last week (and lowered the period to .0001) but the problem
> still remains.      

Unlikely unless it shares system RAM and/or uses proprietory closed source 
drivers

> My next step is to make an attempt at recompiling without the debounce
> code.  I have *some programming experience but a duffer's guide on this
> would be great!  Really, any instructions or recommended reading you could
> suggest would be appreciated.

First stage is to install the tools and libraries using the command:

 apt-get build-dep emc

Then "apt-get source emc" will download and extract the sources to the current 
directory. Run configure in src/ and add -DSIMULATED_MOTORS to the RTFLAGS 
line in src/Makefile.inc - A `make modules_install` as root will compile the 
low level module where the "position debounce" takes place - We don't need to 
worry about recompiling & installing any of the user space parts..

Regards, Paul.