At 10:12 AM 6/15/2003 -0700, Joel Middleton wrote:

>I found this schematic on the web and this is my exact
>circuit except the servo signal is connected to pin 3
>on portb. Also I have all the unused pins connected to
>ground. Anyone see anything wrong with the circuit?

A couple potential problems. (pun)

Running a servo motor from your logic supply is a bad idea.
The motor has relatively large stall current demands, and produces a lot of noise. These both have the potential to reset or crash the micro.

Try providing a separate supply for the servo motor, like four AA cells.
Keep the ground tied between the supplies though as that provides the reference for the pulse.

Also, I've found that I need a series resistor of 100 ohms to 1k between the micro and the servo's pulse input. I've never investigated why, but I've had a few chips blown (Atmel AVRs) when I didn't have that series resistor.

It's never a real good idea to take uP I/O pins directly into the real world.

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