nRF52832 32MHz / 32KHz CLOCK to GPIO

RE: nRF52832 32MHz / 32KHz CLOCK to GPIO

Fred@Eur-Ohm — Wed, 21 Aug 2024 13:59:40 GMT

Hello Bendik,

I have exatly the same question as Shabin excepted I am using a nrf52840.

Is there an update for your answer ?

Is there any other new solution to check the real clock frequency now (2 years later !) ?

The main aim is to fine tune our antenna rf adaptation filters according to the real frequency.

Thank you,

Fred Prin

RE: nRF52832 32MHz / 32KHz CLOCK to GPIO

Shahin97 — Thu, 19 Jan 2023 12:07:21 GMT

Quick reply!

For the 32K this suggestion is perfect. To further understand the 32MHz accuracy testing, I will have to wait for the boards to be made for me to implement this example.

Thank you,

Shahin Haque

RE: nRF52832 32MHz / 32KHz CLOCK to GPIO

Bendik Heiskel — Thu, 19 Jan 2023 10:33:35 GMT

Hi Shahin,

It's not possible to send the 32MHz clock to a GPIO pin. The way we measure the accuracy of the 32MHz clock is to use the radio. The accuracy of the carrier signal is directly dependent on the accuracy of the 32MHz crystal. By configuring the radio to transmit a unmodulated carrier on 2440MHz the frequency offset of the radio/32MHz crystal can be measured using a spectrum analyzer. The radio test sample can be used to configure the radio for this measurement.

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/peripheral/radio_test/README.html#radio-test

The best method for measuring the accuracy of the 32.768kHz crystal is to configure a GPIO pin to toggle on each RTC tick using PPI. This will result on a square wave of half the LF crystall frequency. The PPI trace sample can be used for this testing:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/libraries/debug/ppi_trace.html#ppi-trace

Best regards,

Bendik