Servo does not seem to respond

I have a GWS S03NF servo. I am interfacing it to a MSP430 launchpad. I am powering it with a 4.8V battery pack and the signals are 3.3V CMOS. I have setup a PWM @ 40Hz and also 50Hz with a signal width of 1.3ms. The servo does not seem to respond at all. I checked the continuity of the cables etc. Only when I power up the servo does it start moving and stops.

I have attached the signal waveform.


We don’t carry the GWS S03NF, but it looks like a standard RC servo and it sounds like you are only sending a single pulse width to it. If that is the case, the behavior you are getting does not seem strange. To get your servo to move from one position to the next, try adjusting the pulse width of your signal rather than the frequency.



What I meant below was I tried sending the pulse @ 5Hz too. Also I have increased the pulse width to 1.8ms and still motor does not move. In the waveform its at 50Hz pulse with the pulse width of 1.8ms.


I think I have narrowed down the problem. I am powering it using 4 AA rechargeable 1.2V battery. When I very very lightly put my hand on the metal leads it starts to turn. If I apply the same very very light pressure using a paper weight rock it just does not respond. Should I put a resistance to the power supply?

That sounds like a connection issue. If you post a picture that clearly shows your connections (and soldering, if there is any), I might be able to help find any obvious connection problems.


Got it working. Turns out that I have not connected to the common ground. i.e. the microcontroller ground and the servo negative should have been connected together.

I am glad you got it working. Thanks for letting us know.