Servo question

mynet43

I've seen several references recommending a 4.7K resistor between the Propeller pin and the servo control signal. This is recommended in the support code (servo32.spin), etc.

My question is:

I believe the servo control signal is a high-impedance, input-only signal. If this is the case, then there should be no possibility of the servo signal affecting the Propeller pin, even with a direct connection.

Would someone please clarify the need for a current limiting resistor?

Thanks for your help!

Paul Baker

The reason for the recommended resistor is the possibility of electrical interference on the line.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Mike Green

The other piece is that accidents do happen. I have a Protoboard with mixed +5V and +3.3V sensors, some attached by jumpers. It's safer to have series resistors in those Propeller leads that can tolerate them, just in case I hook things up wrong. If I had some other type of wiring or a +3.3V only system, I'd probably dispense with them.

mynet43

Thanks all.

That's kinda what I thought.

It's to protect you from yourself.

Makes sense now...