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Question on PSC class — Parallax Forums

Question on PSC class

bulkheadbulkhead Posts: 405
edited 2006-05-18 12:54 in General Discussion
I have a servo mounted on a robot to actuate an arm. Currently, the parameter for the limit of travel is 1250. If I increase it to 1300 when I initialize, will it give me more physical servo travel, or will it just set 1300 as the same physical position that 1250 represented? In otherwords, does it just increase the endpoint of travel or does it just split up the position values into smaller physical increments? Thanks.

Comments

  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2006-05-18 12:44
    Actually, you should· find out the physical limits, perhaps using the pc program,
    and then use these limit values for Pmin and Pmax (the pc program uses values 500-2500, so divide by 2).
    Pmin (default 250) corresponds to 0 degrees, Pmax (default 1250) corresponds to 180.0 degrees.
    If your Pmax=1300, then 1300 corresponds to 180.0 degrees.
    So the psc class assumes that the servo has a physical range of 180 degrees
    that corresponds·to·the count range Pmin to Pmax.
    Now, if you use Pmax=1250 and try to set the servo to 1300, then you actually
    try to set the servo beyond 180 degrees.

    regards peter
    ·
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2006-05-18 12:54
    The psc board uses a 2uSec tick, so 500 equals 1 mSec, 750 equals 1.5 mSec, 1000 equals 2 mSec
    so a standard servo would use the range 500-1000, as·1 mSec moves to left, 2 mSec moves to right
    and 1.5 mSec moves to center.
    regards peter
    ·
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