Forum Post: RE: Using External Crystal on MSP432 Launchpad using RTL OS

And this is most likely because the CS ISR inside of the interrupt vector table from startup_ msp432p401r _ccs.c points to the NMI_Handler instead of a custom-defined CS handler, see the SysTick_Handler from the cs_hfxt_start example as reference. This is not an error with the ISR handler but in how the user defines the interrupt vector table. Regards, Ryan