After trying a lot on QTouch Matrix for ATmega8,It didn't work for me. So sharing the trouble here.

I have taken reference from this beautiful article. Here he had provided a schematic and PCB design also. I have followed the same schematic and PCB layout, used same code for ATmega8 @16MHz crystal and with fuse bits: 0xc9ff, still it is not working at all. I got calibrating message on terminal, then after that, when I touch the Pad, it displays random numbers on terminal and that was only for three keys! others are not working. also those three keys are not working covering with a plastic sheet.

If somebody can direct me towards right path and give some tips, it would be better for me to move ahead.
schematic diagram: enter image description here I have set up ATmega8 on General Purpose PCB. touch Pad is connected through jumper wires.Below are Images of the test setup. MATRIX PAD: enter image description here MATRIX PAD Wiring: enter image description here TEST SET UP: enter image description here ATmega8 Board: enter image description here

  • \$\begingroup\$ How much capacitance do you think those long wires can pick up? \$\endgroup\$ May 5, 2015 at 15:15
  • \$\begingroup\$ Long wires may be the issue? \$\endgroup\$
    – isoln
    May 6, 2015 at 5:17
  • \$\begingroup\$ thanks Ignacio Vazquez-Abrams for the comment. there may be one of the problem, but I have read few lines from the article mentioned above, from which i inspired to do this , says: "There's a little problem however. All AVR inputs are protected from overvoltage by the internal Shottky diodes which have very low bandgap of 0.2V. This puts a serious constraint on the design: |quant.suff | should be not above 0.2V, or nothing will work out at all." Can anybody explain me this please? \$\endgroup\$
    – isoln
    May 6, 2015 at 5:59
  • \$\begingroup\$ I thing there is a PCB design fault. I am designing new layout for QTouch Matrix touch pad in altium design software. \$\endgroup\$
    – isoln
    May 7, 2015 at 14:25

1 Answer 1


You have missed the jumpers to join "Y-wires". If you look at page2 fig4 image closely and read the fig4 text in the: QMatrix™ Technology White Paper

enter image description here


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