STS3215 motor: Operating range and position loss in multi-turn mode after power cycle

[Yu-Xuan-Peng]

Thank you so much for open-sourcing the RX1 robotic arm project! I am currently developing a 6-DOF robotic arm and have learned a lot from your excellent design.

I have run into an issue regarding motor control. Since I am using the exact same Feetech STS3215 servo motors as you did, I would like to ask a few questions about your setup:

1. Reduction Gear Motor Range: In your design, is the operating range of the reduction motor strictly limited to 0~100 degrees, or did you enable the "multi-turn mode" on the servo?
2. Position Loss in Multi-Turn Mode: I am currently trying to use the multi-turn mode on the STS3215, but I've noticed that once the power is cut and reconnected, the motor forgets its absolute position (the turn count resets). Did you encounter this issue during your development? If so, how did you solve or work around it (e.g., implementing a homing/calibration sequence on startup)?

Any advice or pointers would be greatly appreciated. Thanks again for your contribution to the open-source community!