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HS-785 Quarter Scale Servo Values? 
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Joined: Thu Nov 10, 2011 12:43 am
Posts: 6
Post HS-785 Quarter Scale Servo Values?
We are trying to figure out how to make this servo work consistently. We are able to get it to rotate by setting it to various values but it always goes more then 3.5 rotations and once it starts we cannot seem to control when it stops. With the other continuous rotation server, we found that 0, 127, and 255 would make it turn left, stop, or turn right. Has anyone figured if there is any way to get it to stop once started or numbers that at least give consistent behavior.

Sat Nov 16, 2013 10:54 pm
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Joined: Sat May 18, 2013 1:24 pm
Posts: 271
Location: Olympia, WA
Post Re: HS-785 Quarter Scale Servo Values?
This servo shouldn't be a continuous rotation servo. Therefore, the values you tell it to turn to would be actual positions: once the servo reaches that position, it should stop turning. What happens when you tell it to go to 127? Does it stop after a while? Theoretically, it should go to one and three-quarters turns.

FTC Team 6424, the 'Oly Cow - Chief programmer.
FRC Team 4450, Olympia Robotics Federation (ORF).

and also quadrotors. Quadrotors!

Sun Nov 17, 2013 5:40 pm

Joined: Thu Nov 10, 2011 12:43 am
Posts: 6
Post Re: HS-785 Quarter Scale Servo Values?
If I set it to 10 and then 300, it goes about 8 turns.
If I set it to 100 and then keep incrementing the amount, it keeps rotating till 255. So, I am assuming the range we use to set it is from around 8-255 but it seems to do 8 rotations instead of the 3.5 noted on their site.
If I set it to zero, 3, 5, or 6 sometimes it will rotate at its 'normal' speed for a few turns. Then it slows down and keeps rotating without stopping. Sometimes I have to power it off to make it stop.

When I was running the program that sets it to 100 first, it didn't always go to the same position which makes it hard to initialize consistently. The one that started at position 10 seems to position itself around the same area a little better.

I am curious if other teams are seeing the same behavior.

Sun Nov 17, 2013 7:07 pm
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Joined: Thu Nov 14, 2013 11:38 pm
Posts: 4
Location: Portland, OR
Post Re: HS-785 Quarter Scale Servo Values?
Per experiments done by us we found the optimal range of usable values to be between 26 and 228. This matches the expected pulse width of between 0.9 and 2.1 millisecond range. You can see further discussions on this specific post

Team 4855 - Batteries In Black

Sun Nov 17, 2013 10:13 pm
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