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SHARP GP2Y0A21YK0F 10-80cm NIGHTMARE — Parallax Forums

SHARP GP2Y0A21YK0F 10-80cm NIGHTMARE

brolloxbrollox Posts: 3
edited 2011-12-14 14:38 in Accessories
Hi,

Just bought 4 of these sensors. Thought i'll quickly hook it up to 5V + filter cap + oscilloscope to Vout (white lead).

The darndest thing - I get no meaningfull data that is range related. The sensor Vout value seems to fluctuate between 3-4 Volts. I tried to correlate the data. I marked a sheet of paper to keep within the range tollerances - i even swithced of the lights......??

Since I have 4 of these sensors I tested more sensors and all of them responded the same way. :blush:



What am I missing - it looks so simple. Does it need some biasing - open collector, emitter maybe?

Please advise

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-12-14 04:52
    Well, if you're powered up right and you're measuring Vout from Ground then there's nothing else to mess up - or needed.
    10cm is 4 inches, so you don't want anything closer than that.
    Some materials reflect IR better than others (some materials absorb IR better than others.)
    Try different objects and point the ranger a bit up and away from your work table.
  • SRLMSRLM Posts: 5,045
    edited 2011-12-14 11:14
    Did you hook up ground to the oscilloscope? Did you try using a multimeter instead? Did you try adding a capacitor across the IR sensor supply leads?
  • ercoerco Posts: 20,256
    edited 2011-12-14 11:18
    Is this the digital one? http://www.junun.org/MarkIII/datasheets/GP2Y0A21YK.pdf
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-12-14 11:36
    If you have the sensor sitting close to a horizontal surface, such as a desk or benchtop, you may be getting reflections from that. Be sure to position the sensor so that all it sees is the desired target.

    -Phil
  • PublisonPublison Posts: 12,366
    edited 2011-12-14 12:40
    erco wrote: »
    Is this the digital one? http://www.junun.org/MarkIII/datasheets/GP2Y0A21YK.pdf

    erco,
    That seems to be analog output also. (Based on your cited PDF).

    The only digital output Sharp sensor I could find is:

    http://www.acroname.com/robotics/parts/R49-IR15.html
  • brolloxbrollox Posts: 3
    edited 2011-12-14 12:50
    Hi,

    Weirdest thing....in desperation i grabbed the rig and ran over to another side of the house....supposedly free from IR interferences. Hooked up a multimeter and voila....it worked as simple and as straight forward as it would be expected to work!!!!

    I immediatly rushed back up to the room to confirm this theory only to find that the problem mysteriously vanished - I honestly dont know what to make of it. I even blanked out all laptop computer IR transceivers in desperation...hahahahaha!! So now its all working with the original configuration - go figure!!!

    Lets keep our collective breath!!!

    Thanks for the help!!!
  • PublisonPublison Posts: 12,366
    edited 2011-12-14 12:55
    Good you got it working!

    Thanks for for the update.
  • brolloxbrollox Posts: 3
    edited 2011-12-14 14:38
    Hi,

    I noticed that the area of the beam width is about 4x2 inches along the length of the sensor @ 80cm - pretty narrow perpendicular to the sensor axis. The beam width balloons a little more along the sensor axis.

    My application requires a glass or poly-carbon window. Both mediums were tested. It was found that if you place the window 90 deg the beam, it causes interference due to reflections.
    It helped by placing the glass panel at an angle.

    Frank
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