/*
 * Toggle PORTB in C programming language for TI Tiva LaunchPad
 * with Wytec EduBase.  On Wytec EduBase board, PB3-PB0 are connected
 * to the four LEDs.
 * Default system clock 16 MHz is used.
 */

#include "TM4C123GH6PM.h"

void delayMs(int n);
void delayUs(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 clock 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 (16 MHz CPU clock)
void delayMs(int n)
{
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3180; j++)
            {}  // do nothing for 1 ms
}

// This function is called by the startup assembly
// code to perform system specific initialization tasks.
void SystemInit(void)
{
    // Grant coprocessor access
    // This is required since TM4C123G has
    // a floating point coprocessor
    SCB->CPACR |= 0x00f00000;
}