Controling a 6v servo of 3.3v

Projects General Guidance
1

hi all,
first off i would just like to say thankyou to anyone who replys :slight_smile:

i need to control 2 servos. theese servos say 5 - 7.4v now not gonna lie. i am using an esp32 with 3.3v logic but i assume it would be similar to 3.3v arduino, thats why i am asking here.

i have read some things online saying that the servo data can be powered off 3.3v no problem with just VCC and GND being 6v. i have tried this and it just makes the servo movment all weird. it moves fast, then slow then not at all and it doesnt actually follow the literal example code for moving a servo.

i have also tried powering the whole servo off the 3.3v logic, now this does in fact make the servo follow the code (most of the time) but it moves really slow and isnt very responcive, due to the undervoltage i assume. i also dont know if the servos are drawing too much current from the seeed studio xiao c3. is there some way i can combat this or some servo driver that can take the 3.3v signal and change the whole logic to 5 or 6v so the servo behaves as i want.

i feel like ideally it is probably better for the esp32 to have the servos powered off some external power source with just the signal coming from the esp32. like i said i tried this though, even had a common GND and the servo misbehaved.

Any help is greatly appreciated,
thankyou. :slight_smile:

EDIT:
i have found out about level shifter ICs but im not sure how i would use this in this case or if it is the right idea.

2

I just happened to have at hand a test board with a 328P running at 3.3V and an attached servo. The standard sweep example sketch seems to run just fine. I haven't done anything special; the servo is powered from the 6V battery supply, and the signal line comes straight from I/O 9 at 3.3V.

The servo came out of my parts drawers and is an inexpensive DXW90 that probably came from one of those Arduino starter kits many moons ago. All in all, pretty generic stuff, and it seems to run just fine. Perhaps not all servos run well with a 3.3V signal but it would seem that some of them do.

3

Just remember the servo supply negative must be tied to Arduino ground, so the voltages are correct with respect to each other,

4

that is strange .
i am unsure why mine isnt working
could it be to do with te servo drawing too much power or something like?

5

As I said, it's possible that some servos just don't work well with a 3.3V signal. It's just a guess though.

6

The servo power supply should be capable of supplying 1 Ampere per servo for small servos (SG90) or 3A per servo for MG996R. 3.3V almost always works for the signal lead.

Example wiring:

servo_pwr
servo_pwr1035×538 42.8 KB

7

As quoted, maybe they will or maybe they won't.

So if you tried it and it doesn't work on your 3v3 signal, simply run the output from your uC through a level shifter, either a commercially made module ( cheap as) or make your own.

Btw.....I don't think the SG90 will work at 7.5v, at least not for long.
Specs say 4.8 to 6.0v.

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ill give that another go with a different power supply. thanks
may i ask what does connecting the grounds together actually do
thanks

9

All signals require a return path. Basically, the electrons come out of the Arduino PWM pin, go through the servo, then return through the ground connection back to the Arduino.

What would happen if you connected an LED to a battery with only one wire?

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Ground is the required "zero" voltage reference for the entire circuit.

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