I am exploring porting software built for MK20DX256VLH7. It uses USB and works fine on the MK20DX256VLH7. We substituted the CPU with the MK20DX256VLL10 (to get more pins and speed) but now the USB does not work properly. Using the same firmware on the MK20DX256VLL10, everything else seems fine (I2C, pins, etc). In the debugger, after plugging it in, I can see it calls the interrupt for USB USBRST and it will also process SOFTOKEN regularly. But that's it. It will not receive the TOKDNE events when the host sends it's SETUP packets. I can see the packets come from the computer using a USB analyzer.
Are there any differences between the USB module on the MK20DX256VLL10 and MK20DX256VLH7? Any ideas of how to troubleshoot this?