I designed a PCB that includes capacitive touch. The circuit works with 5V powered from USB.
When Laptop is connected to 220V line, the PIC can sense capacitance variation.
When Laptop is not connected to 220V line(self battery powered), the PIC can't sense any capacitance variation.
I only add 2 bypass capacitors to the input. I did not do the ground design of the PCB very carefully.
Is the source of the problem PCB ground design? Is it error in the 5V input circuit design? or what else?
What would you suggest me for solving the problem? Can I fix the problem by adding some components to the 5V line?