diff --git a/Group21_Lab06_Task1/main.c b/Group21_Lab06_Task1/main.c
index 42c2771..e6e041e 100644
--- a/Group21_Lab06_Task1/main.c
+++ b/Group21_Lab06_Task1/main.c
@@ -48,3 +48,22 @@ void delay(int us)                              // DEFINING DELAY FUNCTION
     while ((STCTRL & (1 << 16)) == 0);          // Wait until flag is set
     STCTRL &= 0x0;                              // Stop the timer
 }
+
+void SystickHandler(void)
+{                                   // SysTick interrupt handler
+    ontime++;
+    if (ontime < duty)
+    {
+        GPIO_PORTF_DATA_R |= 0x02;  // LED should be ON
+    }
+    else
+    {
+        GPIO_PORTF_DATA_R &= ~0x02; // LED should be OFF
+    }
+
+    if (ontime >= 100)
+    {
+        ontime = 0;                 // Reset counter after one period
+    }
+}
+