arduino-libraries / braccio Goto Github PK

I've spent multiple hours trying to get the Braccio.begin() soft start to work, but cannot get it to behave as documented.

With the default values the arm will twitch around, but not actually lift off the table (if started lying flat). Then the start period will elapse and the arm will suddenly jerk into place.
With non-default values (wondering about the mystery "the sum should be 530usec" values!) things aren't any better.

We can't get the initial position from the servos without additional hardware (the servo .read() returns the last written value, or a default of '93').
We can't easily "park" the arm to a known position because it will generally collapse under its own weight when powered off. The counterbalancing springs do seem to let it remain completely vertical - which looks maximally unstable but is in fact my current approach for a smooth start!

Is something broken in my Braccio (has anyone gotten 'soft start' to work as described)? Or is all of this 'soft start' / SoftwarePWM stuff just a complete red-herring? From the many, many questions about this on Arduino.cc I suspect the latter ... but would love to be proven wrong.

Any pointers would be very welcome, please!