How to check nRF52840 CPU frequency ?

[madhu]

Hi I am working with nRF52840 , since it is said that it can work on 64Mhz, i just want to confirm by using Oscilloscope.

You have any inputs that how i can check the frequency accurately?

Thanks and Regards R Madhu.

[MartinBL]

Hi,

The best way is probably to use a timer, PPI, and a GPIOTE channel to toggle a pin. The Timer base frequency is 16MHz so that means you can toggle a pin at 16MHz, and get an 8MHz signal out that you can measure on. The timer and CPU use the same system clock so this should give you what you need.

[madhu]

Thank you Martin, I have toggled an LED directly writing in to the registers, putting in a while loop and I am able to see 16MHz clock. But how can I make sure that HFCLK of 64MHz is enabled or not??