Force RC PWM at boot

Hi I have enabled RC PWM in the settings for an XL330 servo. I however cannot guarantee that there will be a PWM signal when the servo powers on. How can I guarantee or force the servo into RC Mode regardless on what is on the data pin at boot?

I have tried to switch the servo on after boot using a low side and high side NPN transistor on the servo, however, ground just seems to go through the data pin. And doesn’t reliably kill power to the servo


There isn’t a way to force the servo to always start in RC PWM mode by design, so that the servo won’t somehow get stuck in RC mode without any way to reset it back to a standard operating mode.

Your plan to switch on the actuator after boot once you’re sure that the PWM signal is on would certainly be the most reliable way to get the behavior you’re looking for, and depending on what controller you’re using there may be a way to do so programmatically in your code.

Well I just used a digital signal to drive an NPN BC549 transistor. I tried Hi side switching however the voltage drop was about 2V and the VCC for the servo was about 2.5V.
The low side switching wasn’t reliable in resetting the servo as I think that the servo could remain grounded through the Data pin.

Overall the most reliable was a physical switch, momentary off, but it still sucks that I want some basic servo funtionality and I can’t do it easily. Oh and whilst we are talking about new functionality, I’d like the position limits for RC mode to be configurable.

is there an opensource firmware for the servo?