KL05 internal clock

[ivanrusnacko]

Hello,

We have a project with FEI mode and internal 32 kHz oscillator. It gives us output of 21.97 MHz. We would like to have a 24 MHz clock, so we have to trim the frequency of oscillator. There is a register SCTRIM, which does it, but its value is different in every MCU(as oscillator is callibrated in factory). Is there somewhere a more detail information, what are the weights of bits in SCTRIM register? We cannot use external oscillator because of price reasons. The value of SCTRIM is proportional to value of SCTRIM or value of oscillator frequency?

And what about setting DMX32 bit to 1 in FEI with factory trim value? Will it damage MCU?

[al_muir]

The KL05 device comes from the factory trimmed to 20.97MHz. This is achieved by trimming the slow internal reference clock (IRC) to 32.768 kHz. If you set the DMX32 bit then that will provide a 24 MHz clock using the factory trim value. there is no need to perform a custom trim for your application.

[Hui_Ma]

Hi,

If customer want to do internal clock trim, it need use external clock to do that work (provide bus clock within 8-16MHz).

In fact, so far P&E Multinlink Universal tool does not support Kinetis internal clock trim work.

Just as Alistair, the Kinetis internal slow clock trimmed to 32.768KHz before shipped to end customer.

Customer just need to set DMX32 bit to get FLL output 24MHz.

Thank you for the attention.

B.R.

Ma Hui