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CP7 Touch events are intermittently working


#1

I have a Cobra 2 with a CP7 attached on a machine.
We machined out a metal enclosure and installed it with double sided tape on the edge of the CP7.
The touch events on the 2 buttons i have on the screen are not firing all the time. Actually the buttons don’t even look like they are being pressed on the screen
I have the standard cables connected and am using an external power supply.
i setup the event with


     this.stopbtn.Tap += (sender, e) => this.StopbtnButtonPressed();

     this.startbtn.Tap += (sender, e) => this.StartbtnButtonPressed();


i have another CP7 i am going to try.
any thoughts or suggestions?


#2

Does it work if the screen isn’t mounted? Im wondering if the metal is affecting the capacitive touch sensors on the CP7.


#3

Tried it with a new display as the other is rtv’ed in the hole but same results.
it worked intermittently last week but now doesn’t work at all.
i even tried with the Power Extender Module but same results.
any guesses?


#4

Are you testing in a room with fluorescent lights? If you are, try testing a room without them. And are you using Glide?


#5

I am in a room with fluorescent lights. I am using Skewworks tinkr2.
at our plant all of our lights are fluorescent light.
is there something i can do to fix this like grounding the display case or something like that or am i out of luck?
do the Display T43 Module have the same problem with fluorescent lights?


#6

Further trouble shooting (as the CP7 has the best touch I’ve seen with NETMF/Gadgeteer):

  1. When mounting/unmounting my CP7 in the past I’ve seen the flex cable become loose or detached, check that connection

  2. Try switching cables on the touch

  3. Do you have any high CPU usage threads running that might interfere w/ touch collection?


#7

these links discuss noise, the two most common problems being power supplies and fluorescent lights; I didn’t read them through, but some of them may discuss shielding (?).

http://www.lrc.rpi.edu/publicationDetails.asp?id=124
http://www.optoelectronics-electronicspecifier.com/Displays/Avoiding-EMI-in-capacitive-touch-screens.asp
http://www.lrc.rpi.edu/programs/NLPIP/lightinganswers/pdf/view/LAEMI.pdf
http://www.edn.com/design/sensors/4411529/Aggressively-combat-noise-in-capacitive-touch-applications