/* Toggle LEDs on EduPad with TI Tiva LaunchPad
 * 
 * On EduPad board, PB3-PB0 are connected to the four LEDs.
 * Default clock 50 MHz is used.
 *
 * Built and tested with Keil MDK-ARM v5.24a and TM4C_DFP v1.1.0
 */

#include "TM4C123GH6PM.h"

void delayMs(int n);

int main(void) {
    volatile unsigned char readback;

    // enable PORTB 3-0 as output
    SYSCTL->RCGCGPIO |= 0x02;       // enable clock to GPIOB
    readback = SYSCTL->RCGCGPIO;    // make sure the colock is enabled
    GPIOB->DIR |= 0x0F;             // set PORTB 3-0 as output pins
    GPIOB->DEN |= 0x0F;             // set PORTB 3-0 as digital pins

    for (;;) {
        GPIOB->DATA = 0x05;         // turn on PB2, 0
        delayMs(500);
        GPIOB->DATA = 0x0A;         // turn on PB3, 1
        delayMs(500);
    }
}

/* delay n milliseconds (50 MHz CPU clock) */
void delayMs(int n) {
    int i, j;
    for(i = 0 ; i< n; i++)
        for(j = 0; j < 6265; j++)
            {}  /* do nothing for 1 ms */
}