diff --git a/main.c b/main.c
index 1f24998..6e45d0a 100644
--- a/main.c
+++ b/main.c
@@ -17,15 +17,53 @@ void UART1_WRITE(char data);
 void control_leds_based_on_speed(float speed_kmh);
 void process_nmea_sentence(const char *nmea_sentence);
 
-
 void GPIO_PORT_F_init(void)
+    {   SYSCTL_RCGC2_R |= 0x00000020;    // ENABLE CLOCK TO GPIOF
+        GPIO_PORTF_LOCK_R = 0x4C4F434B;  // UNLOCK COMMIT REGISTER
+        GPIO_PORTF_CR_R   = 0x1F;        // MAKE PORTF0 CONFIGURABLE
+        GPIO_PORTF_DEN_R  = 0x1F;        // SET PORTF DIGITAL ENABLE
+        GPIO_PORTF_DIR_R  = 0x0E;        // SET PF0, PF4 as input and PF1, PF2 and PF3 as output
+        GPIO_PORTF_PUR_R  = 0x11;        // PORTF PF0 and PF4 IS PULLED UP
+    }
+
+
+#define STRELOAD *((volatile uint32_t *) 0xE000E014)    // RELOAD VALUE REGISTER
+#define STCURRENT *((volatile uint32_t *) 0xE000E018)    // CURRENT VALUE REGISTER
+#define STCTRL *((volatile uint32_t *) 0xE000E010)    // CONTROL AND STATUS REGISTER
+#define COUNT_FLAG  (1 << 16)   // BIT 16 OF CSR AUTOMATICALLY SET TO 1
+#define ENABLE      (1 << 0)    // BIT 0 OF CSR TO ENABLE THE TIMER
+#define CLKINT      (1 << 2)    // BIT 2 OF CSR TO SPECIFY CPU CLOCK
+#define INTEN      (1 << 1)     // BIT 1 OF CSR TO ENABLE INTERRUPT
+#define CLOCK_HZ 16000000       // CLOCK FREQUENCY OF EK-TM4C123GXL
+#define SYSTICK_RELOAD_VALUE(us) ((CLOCK_HZ /1000000) * (us) - 1 ) // SYSTICK RELOAD VALUE IN MICROSECONDS BASED ON CLOCK FREQUENCY
+
+#define RED_LED  0x02;
+#define BLUE_LED  0x04;
+#define GREEN_LED  0x08;
+volatile uint8_t LED_STATE = 0;
+
+void systick_setting(void)     // SYSTICK SETUP FUNCTION
 {
-    SYSCTL_RCGC2_R |= 0x00000020;             // ENABLE CLOCK TO GPIOF
-    GPIO_PORTF_LOCK_R = 0x4C4F434B;           // UNLOCK COMMIT REGISTER
-    GPIO_PORTF_CR_R   = 0x1F;                 // MAKE PORTF0 CONFIGURABLE
-    GPIO_PORTF_DEN_R  = 0x1F;                 // SET PORTF DIGITAL ENABLE
-    GPIO_PORTF_DIR_R  = 0x0E;                 // SET PF0, PF4 as input and PF1, PF2 and PF3 as output
-    GPIO_PORTF_PUR_R  = 0x11;                 // PORTF PF0 and PF4 IS PULLED UP
+       STRELOAD = SYSTICK_RELOAD_VALUE(500000);  // SYSTICK RELOAD VALUE 500 milliseconds
+       STCURRENT = 0;                             //CLEARING STCURRENT REGISTER VALUE
+       STCTRL |= (CLKINT | ENABLE | INTEN);       // SET INTERNAL CLOCK, ENABLE THE TIMER AND INTERRUPT ENABLE
+}
+
+void delay(int us)               //DEFINING DELAY FUNCTION
+{
+    STRELOAD = SYSTICK_RELOAD_VALUE(us) ;     // RELOAD VALUE FOR REQUIRED DELAY IN MICROSECONDS
+    STCURRENT = 0;                            //CLEARING STCURRENT REGISTER VALUE
+    STCTRL |= (CLKINT | ENABLE | INTEN );     // SET INTERNAL CLOCK, ENABLE THE TIMER
+    while ((STCTRL & COUNT_FLAG) == 0)        //WAIT UNTIL FLAG IS SET
+    {          // DO NOTHING
+    }
+    STCTRL &= 0x0;                //  STOP THE TIMER
+}
+
+void SystickHandler(void)       //SYSTICK INTERRUPT HANDLER
+{
+    GPIO_PORTF_DATA_R ^= LED_STATE;
+
 }
 
 
@@ -55,10 +93,15 @@ void control_leds_based_on_speed(float speed_kmh)   // Control LEDs based on spe
 
     GPIO_PORTF_DATA_R &= 0x00;                       // Clear all LED bits (assuming LEDs are connected to bits 1, 2, and 3)
 
-
+    if (speed_kmh >= 0.0 && speed_kmh < 10.0)        // Range 0-10 km/h
+        {
+            //GPIO_PORTF_DATA_R |= 0x08;                   // Green LED
+            LED_STATE = GREEN_LED;
+        }
     if (speed_kmh >= 0.0 && speed_kmh < 10.0)        // Range 0-10 km/h
     {
         GPIO_PORTF_DATA_R |= 0x08;                   // Green LED
+
     }
     else if (speed_kmh >= 10.0 && speed_kmh < 20.0)  // Range 10-20 km/h
     {
@@ -78,7 +121,7 @@ void control_leds_based_on_speed(float speed_kmh)   // Control LEDs based on spe
     }
     else                                             // Above 50 km/h
     {
-        GPIO_PORTF_DATA_R |= 0x0E;                   // White LED (Red + Blue + Green)
+        LED_STATE = RED_LED;                         // TOGGLING RED LED
     }
 }
 
@@ -168,6 +211,7 @@ int main(void)
 {
     GPIO_PORT_F_init();
     GPIO_PORT_B_init();
+    systick_setting();
     while (1)
     {
      if (nmea_ready)
diff --git a/tm4c123gh6pm_startup_ccs.c b/tm4c123gh6pm_startup_ccs.c
index d2488a7..0852ecf 100644
--- a/tm4c123gh6pm_startup_ccs.c
+++ b/tm4c123gh6pm_startup_ccs.c
@@ -34,6 +34,7 @@ static void NmiSR(void);
 static void FaultISR(void);
 static void IntDefaultHandler(void);
 void UART1_Handler(void);
+void SystickHandler(void);
 //*****************************************************************************
 //
 // External declaration for the reset handler that is to be called when the
@@ -56,6 +57,7 @@ extern uint32_t __STACK_TOP;
 //*****************************************************************************
 // To be added by user
 void UART1_Handler(void);
+void SystickHandler(void);
 //*****************************************************************************
 //
 // The vector table.  Note that the proper constructs must be placed on this to
@@ -82,7 +84,7 @@ void (* const g_pfnVectors[])(void) =
     IntDefaultHandler,                      // Debug monitor handler
     0,                                      // Reserved
     IntDefaultHandler,                      // The PendSV handler
-    IntDefaultHandler,                      // The SysTick handler
+    SystickHandler,                         // The SysTick handler
     IntDefaultHandler,                      // GPIO Port A
     IntDefaultHandler,                      // GPIO Port B
     IntDefaultHandler,                      // GPIO Port C