Capacitive Touch with nFR52

[Alex]

I'm currently making a device which use nRF52832 and that will integrate Capacitive touch feature. However, I'm actually a bit lost with this post: devzone.nordicsemi.com/.../

And this note : Due to erratum 84 (COMP: ISOURCE not functional), capacitive sensing using the relaxation oscillator method is not usable in a real product, as it will only work reliably in room temperature.

So here are the point I want to validate:

1. If I understand correctly, we can't use the COMP module and will need to use the ADC module which is used to implement RC charge timing method?

2. If so, is there an alternative that will only necessitate 1 pin per button ?

Thanks!

[Einar Thorsrud]

1. Your understanding is correct. The programmable current source (ISOURCE) in the COMP peripheral is so unstable over temperature that it should not be used (erratum 84).
2. The Capacitive Sensor driver from the SDK support RC charge timing using the ADC with a common pin for charging the sensor pads through a resistor. That means that you will only need a single extra pin, regardless of the number of buttons you have (n+1 pins for n buttons).