Don Bradford

Wes:  Very helpful.  So is it fair to say that we get the same quality tracking regardless of whether ASIAIR or ExploreStars is giving the commands?  Also, are the TR and PT tracking functions determined in the firmware or is that just a distinction unique to the ExploreStars?

On Sep 13, 2021, at 1:59 PM, Wes Mcdonald <wesmcd6@...> wrote:

Don and jaimie

The pmc8 firmware has an instruction set that is sent to it by any driver.  There is an instruction that tells the mount to Track and the correct track rate is sent as a parameter.  In response the ra motor rate is set to thst passed parameter and the dec motor is stopped.   

When an application wants to go to an ra/dec coordinate, the app tells the driver where , at which point the driver computes the correct motor counts to get there.  This is a computation that has to consider the slewing behavior of the pmc8 firmware.   The driver sends a Point command to the firmware along with the place to point.   Two calls are made, one to point the ra and one to point the dec.   once these commands are sent the firmware handles the move, ramping up the mount to full slew speed, cruising for the correct amount of time and ramping back down to resume tracking at the target.

Explorestars works similarly although there are some differences in the details.

So it is not exactly  correct to say the driver manages the slew or tracking, rather the driver tells the firmware where to go and what rate to move at, and the firmware acts on those commands.   

Thus if Jaime has the wrong rate in the asiair sidereal rate input the mount will not track.


Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired

Don Bradford
Explore Scientific AR102mm, f/6.5
Explore Scientific 12" Truss Tube dob

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