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Touch sensing design

ypkdani , 10-31-2019, 09:59 AM
Hello all,

i have a problem with my first design of a touch button and a slider on a 4layer pcb (top-layer2-layer1-bottom) using a STM32L162 with its peripheralTouch sensing. As you can see from the image i have design the button and the slider with a shield to increase the noise immunity. My problem is a) the sensitivity that is not enough b) reduce the noise from the leds on the bottom that light up the device.
Up the pcb i have 2mm of plastic so i need to increase the sensitivity of the buttons for detect the slider or the button press. My ideas are:
  • separe the shield for the button and the slider that now is the same
  • to increase the diameter of the button copper from 1.5mm to 3mm and the button shield from 1.5mm to 4mm.
  • increase the gnd plane on the bottom where there are the leds for reduce the noise from these
  • increase the width of the slider from 1cm to 1,5cm and the shield from 1,2 to 2cm if possible

In the image you can see the signal from the button, or slider, from the channel 1 and the shield signal from the channel 2.

Do you have other suggestions??
robertferanec , 11-04-2019, 09:06 AM
I uploaded the button pictures directly so everyone can see them

robertferanec , 11-04-2019, 09:11 AM
I uploaded the slider pictures directly so everyone can see them

robertferanec , 11-04-2019, 09:13 AM
It's not really my area, so I can really hep, but maybe someone else can
ypkdani , 11-05-2019, 03:20 AM

i will try to use the AT42QT2120 touch sensing device that is written can work with plastic panel with thickness up to 3mm for slider.

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