I'm building a bipedal robot and I'm using 7,4V servo motors that can consume 3.9A of current (Feetech FT5835M) and RPi4B, how can I control these servos? I'm thinking about using Adafruit 2327 HAT but I read that it can only operate at 5V, what should I do to control my servos? manufacturer's site I bought them here

  • 1
    research how the servo is controlled ... hint: 7,4 V 3.9 A is irrelevant
    – jsotola
    Commented Apr 8, 2022 at 22:01
  • FeeTech is a good choice: penzu.com/p/cf035eca
    – tlfong01
    Commented Apr 9, 2022 at 2:27
  • FeeTech LX Servos operate at 11V and can do 20kg.
    – tlfong01
    Commented Apr 9, 2022 at 2:37
  • Link to servo technical specs?
    – joan
    Commented Apr 9, 2022 at 6:14
  • @joan manufacturer's site
    – Bocian
    Commented Apr 9, 2022 at 11:32

1 Answer 1


Use an external power supply for the servo.

Connect a wire between the external power supply ground (-ve terminal) and a Pi ground. This ensures that the servo and the Pi have a common voltage reference.

Connect a wire between a Pi GPIO and the control line of the servo. The servo detailed specs says that the control line needs between 0V and 0.45V for low and between 2V and 5V for high. As the Pi outputs 0V for low and 3.3V for high the servo will work okay.

The servo you link appears to be a continuous rotation servo rather than a standard servo. Is that intended?

  • On the web page that I bought it from it had the range of 180
    – Bocian
    Commented Apr 9, 2022 at 12:03
  • The Feetech FT5835M link indicates they are continuous rotation servos.
    – joan
    Commented Apr 9, 2022 at 12:09
  • I contacted the shop for information about this servo and I'm waiting for the response. Isn't it possible to use a continuous rotation servo motor just as a standard servo motor? Can't I just translate rotation speed to an angle?
    – Bocian
    Commented Apr 9, 2022 at 12:39
  • No. A standard servo goes to the commanded angle and stops (the angle is set by the pulse width). A continuous rotation servo spins at the commanded speed and direction (the speed is set in proportion to the distance of the pulse width from 1500 µs, the direction according to whether the pulse width is less than or greater than 1500 µs).
    – joan
    Commented Apr 9, 2022 at 15:17
  • I've looked again at the Feetech site and it may just be a case of unclear translation between English and Chinese. Most of the shop listings seem to suggest it's a standard servo, The shop will know.
    – joan
    Commented Apr 9, 2022 at 15:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.