How to config NRF51822's CLOCK to 32MHz

[chenyu]

Hi: I come across a problem when I debug NRF51822. I don't know how to config its clock.My board XTAL is 16MHz, and I want config is to 32MHz，Is the method below OK? NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
NRF_CLOCK->XTALFREQ = UICR_XTALFREQ_XTALFREQ_32MHz; NRF_CLOCK->TASKS_HFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) ;

Is there a PLL in this IC?

thanks

[RK]

No the 32MHz setting is for if you have a 32MHz crystal. Internally HFCLK is always 16MHz, there's no PLL or frequency doubler.

[chenyu]

Thank you for your answer.Now If I want it work at 16MHz, Whether a outside crystal oscillator is requestd,or it can generate a 16M clock by itself without out cystal oscillator? thanks!

[RK]

This is all in the manual - that tells you the options for generating the 16MHz clock.

[chenyu]

I can't understand your datasheet clearly. I just take down the outside cystal oscillator,and it can't work any more. How to config to let it wake up.

[Zou]

That is to say if I used 32MHz ,I can't change I/O's frequency?