IRC and XTAL - Problem

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by HCTEK on Mon Feb 23 11:01:15 MST 2015

I am facing a problem regarding the clock configuration of my custom board. At the beginning I was using the internal IRC clock "Chip_SetupIrcClocking()"  and no problem occured. I changed the configuration to use an external clock of ~16M through XTAL1 "Chip_SetupXtalClocking()" and the micro seems not running properly. In order to know if the micro is working I have a LED that toggle at a fixed frequency.

When I am in Debug mode the micro works for both IRC configuration, XTAL configuration and IRC & XTAL configuration together. However, when I power reset my board and leave the micro run freely the LED does not toggle.

I confirm with an oscilloscope that the ~16M clock is in XTAL1 PIN.

The IRC must be always configured even if I use an external clock? Or I miss some configuration for an external clock?

My micro is the LPC4337 and I am using LPCOpen libraries.

Best Regards