32.768 kHz Clock out

RE: 32.768 kHz Clock out

Einar Thorsrud — Thu, 07 Jul 2022 06:29:35 GMT

You cannot get exactly 32.768 kHz from the HFCLK, but depending on the accuracy you need perhaps it would be good enough to just use a TIMER and PPI to GPIOTE. Alternatively you can do as suggested in this thread. (In both cases the current consumption would be significant though, so if you need to use this continuously in a low power device that would not be a good idea.)

PCLK32KI is the output of the 32.768 kHz clock, but it is output from the clock to the internal 32.768 kHz clock tree inside the IC. There is physically no way to output this on a GPIO.

RE: 32.768 kHz Clock out

nordQues — Wed, 06 Jul 2022 14:30:10 GMT

Ok, thanks Einar Thorsrud for your quick response. Lets leave aside LFCLK, as mentioned in the question above..

Is there a way to generate 32.768KHz from HFCLK (32MHz) on a nrf52 device?

BTW, what is PCLK32KI mentioned in the product sheet of nrf52840, and how is it accessed? (edited)

RE: 32.768 kHz Clock out

Einar Thorsrud — Wed, 06 Jul 2022 14:17:27 GMT

Hi,

No, that is not possible. Please see my previous answer in this thread, which is still valid and applies to all nRF52 series devices.

RE: 32.768 kHz Clock out

nordQues — Wed, 06 Jul 2022 14:09:50 GMT

Hi Einar Thorsrud ,

Is it possible to output 32.768 KHz on a GPIO pin of a nrf52 (nrf52840) device?

Checking again since it has been 2+ years.. (edited)

Thanks

RE: 32.768 kHz Clock out

Einar Thorsrud — Fri, 02 Oct 2020 08:45:53 GMT

Hi,

It is not possible to output the 32.768 kHz LFCLK signal on a GPIO pin on any nRF52 device, as mentioned here. The closest you can get is half of that (16.384 kHz) by using the RTC to toggle a GPIO via PPI, as described here (the post is old, but still valid).