I'm looking to create low latency capacitive touch buttons for a musical instrument. The response time (from physical touch to touch registered in microcontroller) needs to be around ~2ms or less.
From what I've read it seems like this is possible (and there have even been touchscreens developed with sub 1ms latency – see here!).
Given that I merely want to implement a single button, it seems like it should be achievable. However, I've been shopping around for ICs and everything I can find seems to have 10-16ms response time.
So given the lack of an appropriate IC, how could I create such a sensor myself? Is it merely a matter of doing very fast AC voltage measurements on the sensor pad? – In which case, what is the limiting factor here? Why are all the products on the market so slow?
Best Answer
It seems that you have found low power products that do not need to be so fast as they have not been designed to be used on high performance musical instrument needing fast response time, but as simple user interface buttons that need to be reliable (think of stoves and ovens that need to be robust and extremely sure not to trigger easily by accident or house can burn down).
What you can do is to find a reasonably powerful microcontroller with hardware support for capacitive sensing, and fine tune the accompanying sensing software library to fast response time. Most likely your device would have a microcontroller anyway, or at least it would benefit from it.