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
    Apr 8 at 22:01
  • FeeTech is a good choice: penzu.com/p/cf035eca
    – tlfong01
    Apr 9 at 2:27
  • FeeTech LX Servos operate at 11V and can do 20kg.
    – tlfong01
    Apr 9 at 2:37
  • Link to servo technical specs?
    – joan
    Apr 9 at 6:14
  • @joan manufacturer's site
    – Bocian
    Apr 9 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
    Apr 9 at 12:03
  • The Feetech FT5835M link indicates they are continuous rotation servos.
    – joan
    Apr 9 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
    Apr 9 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
    Apr 9 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
    Apr 9 at 15:33

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