CMSIS example

// credit to definitive guide to the
// ARM Cortex-MO  by Joseph Yiu

#include "vendor_device.h"

void main(void) {
    SystemInit();
    ...
    NVIC_SetPriority(UART1_IRQn, 0x0);
    NVIC_EnableIRQ(UART1_IRQn);
    ...
}
void UART1_IRQHandler {
    ...
}

void SysTick_Handler(void) {
    ...
}