### Project 5 LED chasing

![](media/image-20251121162931514.png)

**1. Introduction**
We often see billboards composed of colorful LEDs. They are constantly changing to form various light effects. In this experiment, we compile a program to simulate LED chasing effect. The long lead of LED is the positive side; short lead is negative.

**2. Hardware required**

- Led *6
- Arduino board *1
- 220Ω resistor *6
- Breadboard *1
- USB cable*1
- Breadboard wire *13

**3. Connection for REV4**

![](media/image-20251121163038945.png)

**4. Connection for 2560 R3**

![](media/image-20251121163114265.png)

**5. Sample Code**

```c
int BASE = 2 ;  // the I/O pin for the first LED
int NUM = 6;   // number of LEDs

void setup()
{
   for (int i = BASE; i < BASE + NUM; i ++) 
   {
     pinMode(i, OUTPUT);   // set I/O pins as output
   }
}

void loop()
{
   for (int i = BASE; i < BASE + NUM; i ++) 
   {
     digitalWrite(i, LOW);    // set I/O pins as “low”, turn off LEDs one by one.
     delay(200);        // delay
   }
   for (int i = BASE; i < BASE + NUM; i ++) 
   {
     digitalWrite(i, HIGH);    // set I/O pins as “high”, turn on LEDs one by one
     delay(200);        // delay
   }  
}
```

**6. Result**
You can see the LEDs blink by sequence.

![](media/image-20251121163204553.png)