Using the ROM API for USB

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by tvink on Tue Mar 24 05:41:11 MST 2015

I am planing on using a 50.0Mhz oscillator ( ENET_TX_CLK that I am using for the RMII Ethernet feature ) as my main clock source for the part.  I was able to get 480Mhz for USB0 and 60Mhz for USB1 and 120Mhz for the BASE_M3_CLK by using the PLLs and dividers in the clock module.

Without a crystal or other clock on XTAL1/XTAL2 pins I know I wont be able to boot from USB since the ROM code expects there to be a clock there.

Can you tell me if I am opening myself up for other troubles if I do not supply a 12Mhz clock on XTAL1?

Will I still be able to use the ROM USB API features?

Is there a way to use the DFU utility if I jump into ROM code from my flash code ( after setting up the USB clocking from my 50Mhz source )?