On Thu, Apr 28, 2011 at 10:39:45AM -0500, Jon Elson wrote:

> So, the readout takes almost a ms.  Now, a lot of people would want to 
> convert this to quadrature.
> One problem shows up immediately, they have 65K and 1 million count/rev 
> versions.  

Converting it to intermediate quadrature seems like a losing
proposition.  Wouldn't you want the hardware to receive this serial
and then present it in HAL directly?  By the time you've received all
the serial you're already running behind - and now you have to
generate a whole mess (arbitrary number?) of quadrature edges at
breakneck speed (but slow enough for regular encoder hardware to count
them correctly).  I can't see how you can even be sure of being able
to burst enough edges in another whole servo cycle.

If nothing else this will fool a timestamp based sub-period velocity
estimate algorithm into giving you something crazy, which defeats
our new pid features.

It seems like a custom firmware to read the protocol is the way to go
here, not custom hardware that tries to convert to quadrature.


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