Problem with RC servo connect to pi

[beylow]

Hi there,

I've got some problem with RC servo.
I'm using a servo which I bought from Sparkfun. https://www.sparkfun.com/products/9064
Since it requires 5V voltage and lots of currents, I have to use a external power for servo.
I've followed the instruction on http://learn.adafruit.com/adafruits-ras ... r/overview.
I used a 5V phone charger instead of battery.
When I connect the signal cord to raspberry pi, servo kept running until it reached the maximum angle, even before I issued the python code to control servo. Now, I cannot figure out why it is like this.
Does anyone have an idea?

Thanks a lot.

BTW. I've tried this under both the latest Wheezy and Occidentalis firmware, same result.

[beylow]

Up. Up.

[joan]

Possibly noise from the floating control signal. Does it operate properly once your program starts?

[beylow]

Possibly noise from the floating control signal. Does it operate properly once your program starts?

It doesn't.
I have even tried it with another pi, same problem.

[alexeames]

Have you connected the GND on your power supply to Pi GND?

Which pin are you attaching it to?

Have you seen the photos and layout of how I did it?
Do they match with yours?
http://raspi.tv/2013/how-to-make-your-o ... aving-demo

[beylow]

Have you connected the GND on your power supply to Pi GND?

Which pin are you attaching it to?

Have you seen the photos and layout of how I did it?
Do they match with yours?
http://raspi.tv/2013/how-to-make-your-o ... aving-demo

Hey alexeames.
It actually works with your configuration!

Thanks a lot!

I was trying to use the servo to open my door. But sadly, the servo torque isn't powerful enough. I have to consider buying another servo.

[alexeames]

Way to go. Excellent. Yes you'd need a pretty large and powerful servo to handle a door.