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Quick question about Prop and Servos... — Parallax Forums

Quick question about Prop and Servos...

SteelSteel Posts: 313
edited 2009-08-31 20:23 in Propeller 1
I know servos work well when the power supply is 5V.

Can I connect a prop pin directly to the control and do the PWM with it only being 3.3V, or do I need to amp the voltage level on the signal up to 5V?

Thanks
Shaun

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-08-27 03:55
    Most servos will work just fine with a 3.3V logic level input. You might put a 1K resistor between the Prop I/O pin and the servo control line. It's not necessary, but it will reduce the noise from some motors coming back through the control line.
  • Dave MatthewsDave Matthews Posts: 93
    edited 2009-08-31 19:56
    Any danger you think of the control line pumping current back into the Prop I/O pin if the servo is driven by an external force? Perhaps acting as a generator?

    Dave
  • Mike GreenMike Green Posts: 23,101
    edited 2009-08-31 20:16
    "Any danger"? Sure, if the internal servo control circuitry is defective or really terribly designed or both. Under normal circumstances with a reputable manufacturer, no.
  • Dave MatthewsDave Matthews Posts: 93
    edited 2009-08-31 20:23
    Thanks! That has been a concern of mine...

    I am in the process of replacing (4) 150 ohm resistors on my prop interface to servos to the 1K you suggest. I started with the 150 ohm resistors as that was what is used on the prof. development board.

    Thanks for your posts, this forum is very helpful...

    Dave
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