AnsweredAssumed Answered

Can the L26Z with 32Khz Xtal generate a clock for USB MSB Device

Question asked by Neil Hancock on Jul 21, 2015
Latest reply on Jul 30, 2015 by Neil Hancock

Hi, I'm using the KL26Z with an external 32Khz crystal for time keeping, which can generate

I'm trying to set up the USB to be a device - kboot - following some of the examples, and the first setup is the clock.

Working through KDS300 PE configuration for the  MKL26Z128VFT4, its wanting a 48Mhz clock.

I'm not clear on the basics of the MCG modes as to what I'm looking for - what multipliers I can try for, and whether the L26Z is designed to do this from 32Khz xtal.

I have run through setting up a USB MSC device for the FRDM-K20 following the excellent examples from McuOnEclipse, and it worked for setting up for a 24Mhz clock.

So can I set up the L26Z for the USB MSC device clock of 48Mhz or 24MHz ?

Here is what i've tried

I create a Clock Config 1 with Clock Source Setting 1- for normal mode

I use Clock Config 0 with Clock Source Setting 0 for USB mode

I set the MCG Mode to FBI to be able to the use the Fast Internal Clock (4Mhz/2Mhz), This then allows be to generate a 47.972353Mhz clock - (close to 48Mhz)

The CPU component is error free, however I can't get the USB Component to accept the 47.97352Mhz for its 48Mhz clock

Any help appreciated


Update: Actually I was close. For the USB_LDD component, I needed to input a 48Mhz clock frequency with an error that allowed the 47.972Mhz clock to be selected. ( I was double clicking the available frequency and then inputting the error - which it didn't like)  So I wonder if anybody has some comments as to if this should work?


Message was edited by: Neil Hancock