led.h

// Led Initialisation
#include "MKL25Z4.h"
void initLED(void)
{
    // Enable Clock to PORTB and PORTD
    SIM->SCGC5 |= ((SIM_SCGC5_PORTB_MASK) | (SIM_SCGC5_PORTD_MASK));

    // Configure MUX settings to make all 3 pins GPIO
    PORTB->PCR[RED_LED] &= ~PORT_PCR_MUX_MASK;
    PORTB->PCR[RED_LED] |= PORT_PCR_MUX(1);
    PORTB->PCR[GREEN_LED] &= ~PORT_PCR_MUX_MASK;
    PORTB->PCR[GREEN_LED] |= PORT_PCR_MUX(1);
    PORTD->PCR[BLUE_LED] &= ~PORT_PCR_MUX_MASK;
    PORTD->PCR[BLUE_LED] |= PORT_PCR_MUX(1);

    // Set Data Direction Registers for PortB and PortD
    PTB->PDDR |= (MASK(RED_LED) | MASK(GREEN_LED));
    PTD->PDDR |= MASK(BLUE_LED);

    PTB->PSOR |= (MASK(RED_LED) | MASK(GREEN_LED));
    PTD->PSOR |= MASK(BLUE_LED);
}

void flashLed(void)
{
    PTB->PCOR |= MASK(RED_LED);
    delay(100000);
    PTB->PCOR |= MASK(GREEN_LED);
    delay(100000);
}