K20 Processor Expert USB Clock Problem

[FarhanH]

You have to give it to Freescale for providing so much documentation on everything they have. It is very detailed and includes almost everything you would need to know. BUT, it is very much like Microsoft documentation, meaning, you have lots of detailed information on everything except it's not very practical about anything. I wish they would create more practical documentation...

Anyways, I am having trouble using the processor expert HID component on the K20 Freedom board. The USB_LDD clock setting doesn't accept any clock from the CPU. I have tried both FLL and PLL at different speeds including 48MHz etc but it doesn't seem to accept it. PEE doesn't work as it complains about needing FLL. In FEE, 40MHz looks like the upper limit and the USB_LDD component complains about USB timing being impossible. Doesn't seem like they will work together.

CW 10.3

USB Stack 4.0.3

I think the USBUG is also in need of an update. Especially on the "Developing Applications" section.

I really like the products and their capabilities but the amount of time I am spending trying to work around different issues is crazy. Every time I make a little progress I get hit with another gotcha.

Thanks!

[BlackNight]

I have not used HID yet, but I'm using CDC with the FRDM-K20D50M.

USB CDC with the FRDM-K20D50M | MCU on Eclipse

The screenshots/settings shown should help you to get the right clock configuration.

I hope this helps.

[Hui_Ma · Accepted solution]

Hi,

FRDM-K20D50M provide external 8MHz crystal and external 32.768KHz crystal, the PLL and FLL can output 48MHz clock for USB module. Customer need to check the MCG clock setting and USB clock setting at Processor expert processor component.

Please check attached picture about USB clock setting as an example.

Wish it helps.

[FarhanH]

Wow, so it seems like filters are a good and bad thing in CW! Thanks Hui_Ma and Erich.

Turns out I needed to enable advanced options in processor expert in order to see the USB clock gating. I am attaching the photos from Basic in case anyone else comes across similar issues.