Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: mewakitty on July 12, 2012, 01:57:33 PM

Title: Servo grinding issue
Post by: mewakitty on July 12, 2012, 01:57:33 PM
Hi everyone,

I am new here :) I am working on a robotic arm. I have 9 S777 servos (I didn't build the arm, so this wasn't my selection). The box they came with the servos says timing is between 1ms and 2ms (so standard). I have code that puts that signal out with a frequency of 50Hz.

Unfortunately, my servos are always grinding. They don't move from their position and instead make the grinding noise. I have varied the pulse width from 1 to 2ms, and there is no difference.

I connected the servo to an external power source (it's high power), so it always supplies 6V. The current spikes whenever I send a signal, and I don't think that should be happening. So I have everything disconnected...

Is there a chance the servos require different timing? Other ideas?
Title: Re: Servo grinding issue
Post by: Pogertt on July 12, 2012, 06:43:09 PM
Are you providing the 1 to 2 msec pulse at the proper refresh rate?

http://www.pololu.com/blog/17/servo-control-interface-in-detail (http://www.pololu.com/blog/17/servo-control-interface-in-detail)

Link provides details of timing required.