topic K66 - PLL Clock source in Kinetis Microcontrollers

K66 - PLL Clock source

Masmiseim — Thu, 01 Dec 2016 11:08:07 GMT

Hello,

I have a question about the Kinetis K66 controller. You can switch the input clock of the PLL between the System Oscillator and the IRC48M (labelled at the picture). But where can I configure the switch. Sorry for the trivial question, but I couldn’t find the register to configure it.

Thanks and regards

Re: K66 - PLL Clock source

mjbcswitzerland — Thu, 01 Dec 2016 14:28:54 GMT

Hi Markus

I am not 100% sure, but think that the image is misleading - I think that PRDIV is in fact connected to the same signal as FRDIV, meaning that the source is selected by MCG_C7.

See the following too:
http://www.utasker.com/kinetis/MCG.html
whereby they are shown as connected.

Possibly the additional gate is there to "signify" that only two settings of the three are actually 'workable' for the PLL input (which can't use the 32k input).

Another diagram in the K66 manual show the selected using the same switch:

Regards

Mark

Re: K66 - PLL Clock source

Masmiseim — Thu, 01 Dec 2016 14:47:30 GMT

Hey,

thanks for the reply.

I thought also in this direction as it would be similar to other Kinetis controllers. But the Online Clock-Tool had confused me again. You can configure both switches independently:

Maybe a misleading Image in the Reference manual plus a Bug in the clock tool?

Regards

Re: K66 - PLL Clock source

Robin_Shen — Fri, 02 Dec 2016 07:39:44 GMT

Hi Markus,

You can find the description in the sections"27.1.1 MCG oscillator clock input options" of K66P144M180SF5RMV2.

After double-click the "OSCSEL PLL", the "IRC 48MHz" can be selected.

Best Regards,

Robin

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Re: K66 - PLL Clock source

Masmiseim — Fri, 02 Dec 2016 11:11:14 GMT

Hello Robin,

So, the two switches in the Flow-Diagram are actually one single switch like Mark already mentioned.

Thanks for the confirmation.

Regards

Markus