LedBlink.c

//***************************************************************************************
// Name:   		LedBlink.c
//
// Author: 		Sergio PL                                                                 
//         		http://github.com/sphanlung/                                               
//
// Device: 		LM4F120/TM4C123, Tiva C Series microcontroller                 
//
// Description: This is a LED blinker using the on-board RGB LED and switches in the 
// Tiva C Launchpad board. When no switches are pressed, the blue LED stays on. When SW1
// is pressed, the blue and green LEDs will blink. When SW2 is pressed, the red and blue
// LEDs will blink.
//
//***************************************************************************************

#include "tm4c123gh6pm.h"	// Header file accesses registers in TMC123 microcontroller

//define easy to read names for registers
#define GPIO_PORTF_DATA_R       (*((volatile unsigned long *)0x400253FC))
#define GPIO_PORTF_DIR_R        (*((volatile unsigned long *)0x40025400))
#define GPIO_PORTF_AFSEL_R      (*((volatile unsigned long *)0x40025420))
#define GPIO_PORTF_PUR_R        (*((volatile unsigned long *)0x40025510))
#define GPIO_PORTF_DEN_R        (*((volatile unsigned long *)0x4002551C))
#define GPIO_PORTF_LOCK_R       (*((volatile unsigned long *)0x40025520))
#define GPIO_PORTF_CR_R         (*((volatile unsigned long *)0x40025524))
#define GPIO_PORTF_AMSEL_R      (*((volatile unsigned long *)0x40025528))
#define GPIO_PORTF_PCTL_R       (*((volatile unsigned long *)0x4002552C))
#define SYSCTL_RCGC2_R          (*((volatile unsigned long *)0x400FE108))

//   Global Variables
unsigned long SW1, SW2;  	// input from PF0 and PF4

//   Function Prototypes
void PortF_Init(void);		
void Delay(void);

// 3. Subroutines Section
int main(void){    
  PortF_Init();        			// Call initialization of port PF0-PF4    
  while(1){
    SW1 = GPIO_PORTF_DATA_R&0x10; 	// read PF4 into SW1
    SW2 = GPIO_PORTF_DATA_R&0x01; 	// read PF0 into SW2
    if(SW1 == 0x00){              	// zero means SW1 is pressed
      GPIO_PORTF_DATA_R = 0x08;   	// LED is green
     } 
    else if(SW2 == 0x00){               // 0x10 means SW1 is not pressed
      GPIO_PORTF_DATA_R = 0x02;  	// LED is red
     }
    Delay();				// wait 0.1 sec
    GPIO_PORTF_DATA_R = 0x04;    	// LED is blue
    Delay();                     	// wait 0.1 sec
  }
}

// Subroutine to initialize port F pins for input and output
// PF4 and PF0 are input SW1 and SW2 respectively
// PF3,PF2,PF1 are outputs to the LED
void PortF_Init(void){ 
  volatile unsigned long delay;
  SYSCTL_RCGC2_R |= 0x00000020;     // 1) F clock
  delay = SYSCTL_RCGC2_R;           // reading register adds a delay   
  GPIO_PORTF_LOCK_R = 0x4C4F434B;   // 2) unlock PortF PF0  
  GPIO_PORTF_CR_R = 0x1F;           // allow changes to PF4-0       
  GPIO_PORTF_AMSEL_R = 0x00;        // 3) disable analog function
  GPIO_PORTF_PCTL_R = 0x00000000;   // 4) GPIO clear bit PCTL  
  GPIO_PORTF_DIR_R = 0x0E;          // 5) PF4,PF0 input, PF3,PF2,PF1 output   
  GPIO_PORTF_AFSEL_R = 0x00;        // 6) no alternate function
  GPIO_PORTF_PUR_R = 0x11;          // enable pullup resistors on PF4,PF0       
  GPIO_PORTF_DEN_R = 0x1F;          // 7) enable digital pins PF4-PF0        
}

void Delay(void){unsigned long volatile time;
  time = 727240*200/91;  // 0.1sec
  while(time){
    time--;
  }
}