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Simple PICAXE Servo question

I just got my PICAXE dev board and have been enjoying the learning process.  Thanks for al the informative posts that I have been able to read.

I'm toying with one of those little blue sg90 servos.  I know the min and max positon values are supposed to be 75 and 225 per the PICAXE manual.  However, my servo feels like to is fighting a hard stop when swung to position 75.  The hard stop seems to be at about 85 or so.

My queston: If I order, say, five little blue sg90s will they all have the same hard stop values?  What is the best way to deterime the hard stop values without wrecking the servo?

I know it is simple to limit to position value once the hard stop is understood (if b1 < 85 then b1 = 85),  but finding the hard stop points is what I am after.


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Thanks guys.

I have four of those and they are all slightly different. (I bought five, but one died almost immediately.) Now I am buying bigger / better servos.

For mine, the bottom end seems to be about 75, but the top end goes up around 250 give or take according to which one it is.  For one thing, these 9g servos can be made by different companies and still labeled 9g. They can be slightly different even from the same company, however.

If it is at the end of travel, you will hear it chattering (clicking). stop right away and change the value you are sending until the chattering stops.

likely have lower quality standards and will likely have some drift in their lock to lock numbers (ie as you pointed out 85 seems to work as the low side for the servo you are testing). I have no experience myself and don't recall for sure reading elsewhere, but, trial and error is the best method I know of for finding min/max numbers. Just because the specification(?) says 1 to 2 ms for min/max doesn't mean that every servo out there will meet that specification.