External clock source setup on LPC11xx

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by Mesozoic on Thu Oct 31 17:35:54 MST 2013
Would someone be kind enough to share how they got their LPC11xx chip to use an external oscillator?  I've got an 8 MHz crystal plumbed into the XTAL pins and can see it resonating on the scope, but there's no clear description of how to set it up via the C API.  Of course, I don't mind bitbanging either, but I figured I'd at least try to use one or the other exclusively.

I see Chip_Clock_SetPLLBypass(true, false); as a way of specifying the external clock source usage; I'm assuming my 8 MHz crystal is low frequency, hence the false in the 2nd parameter.

What else needs to be done?  A call to Chip_Clock_SetMainClockSource(SYSCTL_MAINCLKSRC_PLLIN)?