Doubts when controlling servo motor

[AwDw]

This post is about controlling servos using PWM. (using microcontrollers(TIVA LAUNCHPAD,TM4C123GH6PM) and the raspberry pi 2.)

I have created a signal using PWM and the raspberry pi to control the tower pro SG 90.The problem I encountered was that in the datasheet of the servo it says that you need a 5V PWM signal to control it, and my raspbberrypi/tiva can only provide 3.3V on its pins.I tried using the 3.3V pins: I found out that the neutral position(0°) worked well but the +90° and -90°didn´t, they only reached +45°/-45° approximately.

So, do i need to make and extra circuit using OPAMs to "amplify" the output pins or did I do anything wrong?

Link to the servo datasheet: **broken link removed**

 

[betwixt]

Not an op-amp. You could use them but the circuitry would be fairly complicated. The PWM signals are logic signals - only two states, low and high, what you need is a level converter that makes the high 5V instead of 3.3V. Do a search for logic level converters and it should come up with many solutions.

Brian.

 

[KlausST]

Hi,

Or a bjt and two resistors...and an inverted PWM.

Klaus