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Thread: Are resistors needed with rotary encoders?

  1. #1

    Are resistors needed with rotary encoders?

    I picked up a couple ec11 rotary encoders and have been using the encoder library and things were working great but now they are not, turning the knob causes my teensy LC to reboot.

    I did not have any resistors on the power feed to the encoder, maybe I should have? If so how would I size these? Is there a chance I damaged the board?

  2. #2
    Senior Member
    Join Date
    Apr 2013
    You do not normally need resistors, since you would use the internal pullups on the pins and not have a VCC supply at all. If you do have a VCC to the encoder then you may have a situation where one encoder position produces a short VCC/GND and that can be pretty problematic. Tests would be to monitor the voltage with meter or scope while turning the encoder (the IO pins should change zero to three point three volts, Gnd and any VCC should be steady) also try loading blink and rotate encoder (in case software weirdness is in play).

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