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"Buggy" resistive touch buttons on QuickStart — Parallax Forums

"Buggy" resistive touch buttons on QuickStart

CameronMCameronM Posts: 57
edited 2011-06-13 21:30 in Propeller 1
Hello,

I just received my QuickStart Board today and I do like it; however, I am trying the Touch Buttons LED Demo that is posted on the Parallax Semiconductor website, but the LED's and/or resistive touch buttons seems to be "buggy". One minute the LED's are on and I am not touching the resistive touch buttons. Then the LED’s will flicker in a random order and then turn off except for one or two LED’s. Then some times it will work fine. I have tried changing the sampling time and the number of required highs to return true to try to see if that helps and sometimes it works and sometimes it does not. I was wounding if anybody who has a QuickStart Board has had experienced any type of problem like this or is this typical. Also can it be fixed through software or is it a hardware issue.

Thank you,

CameronM

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-06-11 20:00
    CameronM,

    This is discussed several places.

    Try here. The version I wrote works well for me. I think it might depend on the humidity in your area though.

    Duane
  • RaymanRayman Posts: 14,876
    edited 2011-06-13 17:40
    Perhaps Parallax should consider putting in pads for a "real" pushbutton where these resistive ones are... I.e., in parallel.

    I think they're going to have a lot of trouble with those switches. But, if there were an easy way to solder in regular SMT or thru switches, people could upgrade themselves...

    The upgrade path would also be a gentle warning that the resistive switches may not be 100%
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-06-13 19:21
    Ray,

    I didn't really like the button pads when I first tried them out either but after changing the code a bit, they work fine.

    I'm not sure if it's dependent on the humidity or something. But I've been using mine several days without a problem.

    Duane
  • Daniel HarrisDaniel Harris Posts: 207
    edited 2011-06-13 19:46
    Rayman,

    The pads in parallel with the touch buttons might be a good idea. The Quick Start board isn't "my baby", but I'll suggest the idea to David (it's his).
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-06-13 21:30
    One thing I've discovered with the touch buttons is that the 60 Hz e-field in my shop is a much more powerful determinant of switching than dry finger conductivity to Vss. Even by touching a screwdriver tip to just the center conductor of the switch contacts, I'm able to make the switch "close" due to the swings in the surrounding electric field. The affected LED will flicker at the beat frequency between 60 Hz and the sampling frequency. That may answer why some have noticed so much flicker.

    -Phil

    Addendum: This e-field effect might also affect the behavior of the touch buttons when mezzanine boards are plugged in.
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