12 turn pots and calibrating Mr. Robot's Usonic sensor

MatthewMatthew Posts: 200
edited 2005-01-30 - 01:10:51 in General Discussion
First, what's a 12 turn pot? The directions tell me "rotate the zero adjust pot fully counter-clockwise (12 turn pot)"

Second, based on the calibrating instructions from http://www.mrrobot.com/usonic.html

I can't figure out why my sensor is reading eratic measurements despite its distance from any object.

Am I reading the directions correctly in that I only need Pin1 for VDD, Pin2 for VCC, and Pin6 for the analog output to my ADC?

Thanks.

Comments

  • MatthewMatthew Posts: 200
    edited 2005-01-29 - 02:46:02
    Okay, weird. Now it's just reading 0.02v and 0.04v. I've been playing with all of the measurements and still no luck [noparse]:([/noparse].
  • ForrestForrest Posts: 1,341
    edited 2005-01-29 - 04:17:36
    A 12 turn pot means you can make (12) 360 degree rotations of the shaft. Compared to a standard pot - which only allows for (1) 360 degree rotation.
  • MatthewMatthew Posts: 200
    edited 2005-01-29 - 05:25:17
    Okay, thanks Forrest.

    Now my problem is regardless of the adjustments I make to any of the pots, it reads 0.03 volts. I guess I'll give Mr. Robot a call tomorrow.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-01-29 - 22:00:19
    You may be using the two end posts of the potentiometer, Pots ussually have 3 terminals 2 are for the supply and the resistance between them is constant (turning the pot doesn't change the resistance) the third is the wiper and its resistance changes with turning the pot. The addition of the resistance between the wiper and one end plus the resistance between the wiper and the other end is equal to the resistance between the two ends.
  • MatthewMatthew Posts: 200
    edited 2005-01-30 - 01:10:51
    Thanks Paul, but I it's working now. Seems like my 9v battery wasn't full.
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