32.768 kHz Clock out

[WaKo]

Dear Nordic Developer Zone,

Is there a way to set the LFCLK (32.768kHz) on a GPIO using nRF52811 ?

I want to use this clock for controlling another device.

Best regards

[Einar Thorsrud]

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).

[nordQues]

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

[Einar Thorsrud]

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.

[nordQues]

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)

[Einar Thorsrud]

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.