#include "inc/tm4c123gh6pm.h"

#include

#define NVIC_ST_CTRL_COUNT 0x00010000 // Count flag

#define NVIC_ST_CTRL_CLK_SRC 0x00000004 // Clock Source

#define NVIC_ST_CTRL_INTEN 0x00000002 // Interrupt enable

#define NVIC_ST_CTRL_ENABLE 0x00000001 // Counter mode

#define NVIC_ST_RELOAD_M 0x00FFFFFF // Counter load value

void SysTick_Init(void){

NVIC_ST_CTRL_R = 0; // disable SysTick during setup

NVIC_ST_RELOAD_R = NVIC_ST_RELOAD_M; // maximum reload value

NVIC_ST_CURRENT_R = 0; // any write to current clears it

// enable SysTick with core clock

NVIC_ST_CTRL_R = NVIC_ST_CTRL_ENABLE+NVIC_ST_CTRL_CLK_SRC;

}

void SysTick_Wait(uint32_t delay){

volatile uint32_t elapsedTime;

uint32_t startTime = NVIC_ST_CURRENT_R;

do{

elapsedTime = (startTime-NVIC_ST_CURRENT_R)&0x00FFFFFF;

}

while(elapsedTime <= delay);

}

void SysTick_Wait10ms(uint32_t delay){

uint32_t i;

for(i=0; i

SysTick_Wait(500000); // wait 10ms (assumes 50 MHz clock)

}

}

void GPIO_Init(void){

SYSCTL_RCGCGPIO_R |= 0x12; // 1) activate port E, and B

while((SYSCTL_PRGPIO_R&0x012)==0){}; // allow time for clock to stabilize

// 2) no need to unlock PD1-0

GPIO_PORTD_DIR_R |= 0x2C; // 3) make PD2 & 3 & 5 outputs

GPIO_PORTD_DIR_R &= ~0x03; // 3) make PE0 & PE1 input

GPIO_PORTD_AFSEL_R &= ~0x0B; // 4) regular port function

GPIO_PORTD_DEN_R |= 0x12; // 5) enable digital I/O on PD2, 3, &5

}

int main(void){

GPIO_Init();

SysTick_Init();

while(1){

if( (GPIO_PORTD_DATA_R & 0x09) == 0x09){

GPIO_PORTD_DATA_R |= 0x02;

SysTick_Wait10ms(10);

while ( (GPIO_PORTD_DATA_R & 0x09) == 0x09){

GPIO_PORTD_DATA_R |= 0x04;

}

}

else if( (GPIO_PORTD_DATA_R & 0x09) == 0x01){

GPIO_PORTD_DATA_R = 0x04;

SysTick_Wait10ms(10);

GPIO_PORTD_DATA_R = 0x00;

SysTick_Wait10ms(10);}

else if( (GPIO_PORTD_DATA_R & 0x09) == 0x08){

GPIO_PORTD_DATA_R ^= 0x02;

SysTick_Wait10ms(10);

GPIO_PORTD_DATA_R ^= 0x04;

SysTick_Wait10ms(10); }

else

GPIO_PORTD_DATA_R &= ~0x02;

GPIO_PORTD_DATA_R &= ~0x04;

}

}

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