CapSense for waking up device from deep sleep

[Nadeem]

Hello all, is it possible to wake-up the device from deep sleep using cap sense.

How reliable is the ADC cap sense, Im little confused as some people say CapSense is not good for production products.

Is it possible  to enable and disable the capsens with a repeated time to save power?  Does the CapSense with saadc consume allot of power?

Thanks,

Nadeem

[Einar Thorsrud]

Hi,

Hello all, is it possible to wake-up the device from deep sleep using cap sense.

The simple answer is no. The nRF does not have any functional built-in capsense capabilities, so you will need to also use SW for capacitive sensing. You could sleep for a while, then wake up and check if there is any activity on the capacitive sensor, then go back to seep before checking again later, though. Alternatively, you could use a dedicated cap sense IC connected to the nRF via a GPIO for wakeup. In that case, the nRF would be able to wake up on GPIO interrupt, also from system off.

How reliable is the ADC cap sense, Im little confused as some people say CapSense is not good for production products.

The nRF52832 COMP cap sense solution is not usable for production. The SAADC solution may be good enough, but we have not done extensive testing and the calibration algorithm, etc. is simple. You should think of the SDK cap sense implementation more as a proof of concept. You need to do a substantial amount of work yourself to tune it and possibly improve the algorithm before using it if you expect good quality.

Is it possible  to enable and disable the capsens with a repeated time to save power?  Does the CapSense with saadc consume allot of power?

Yes. It is possible to enable sensing with a timer, and yes, the SAADC method will consume a lot of power while sampling, but of how much energy depends on the configuration and how often you sample.