Not able to set 50MHz clock source for KV5 processor with MCUXpresso 10.1.1 and SDK 2.3.0

[tomaszziajko]

Hi,

I use TWR-KV58F220M board that has 50MHz external clock source and I am not able to set 50MHz in the MCUXpresso 10.1.1 and SDK 2.3.0. The tool tells me that the maximum allowed value is 48MHz. Is this a bug with the recent version of toolchain?

I assume that I should be able to set 50MHz as the reference clock, since the devboard i factory equipped with 50Mhz clock source by NXP.

Moreover using KDS with legacy KSDK 1.2 I am able to set 50MHz as clock frequency for this board, and I can confirm that such configuration works and has right peripheral timing (checked with oscilloscope).

Thank you for your help,

Best regards,

Tomasz Ziajko

[jorge_a_vazquez]

Hi Tomasz Ziajko 

Yes, you can set this frequency in the twr board, and as you see there is not problem in the functionality. the waringn that you see is because the funcionality of the OSC in the external reference clock mode for frequency above 48 MHz may not be realiable for the whole range of the chip operating conditions.

For example in datasheet you can find a note in the frequency limits, which specify a max of 48 MHz:

Other frequency limits may apply when external clock is being used as a reference for the FLL or PLL.

Hope this could help you.
Have a great day,
TIC

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