I am trying to design a PCB with some capacitive controls. My first iteration did not seem to work well:
This was a 2-layer 1.6mm board with one circular control, and 5 buttons. The board is 48mm wide. The controller is a CY8C5468LTI-LP026. The controls were designed using the Cypress Touch Controls in Altium Designer.
The response from these sensors was very poor. One or two of them seemed to work OK, but there was a lot of interference between sensors, and a couple of them barely worked at all (even when looking at the raw signal).
I have seen recommendations for just about every possible way of laying this out, including a hatched ground plane under the sensors. No ground plane at all. Ground around the sensors.
My questions:
- Is there something obviously wrong with the PCB layout?
- Should I use the Cypress Touch Controls Altium Library, or should I do something else?
- Should I have used a hatched ground plane around the controls on the top layer?
- Should I have used a hatched ground plane on the bottom layer.
- Are the controls too big and too close to each other?
