This demo is a countdown for 5 seconds, that is followed by a buzzer.
For every second, an LED lights up, and by the fifth second the buzzer goes off.

 

Video Player

 

Code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
//define the outputs
 
const int LED2 = 2;
const int LED3 = 3;
const int LED4 = 4;
const int LED5 = 5;
const int LED6 = 6;
const int buzOutPin = 12;
 
//****************************<wbr />******************************<wbr />**********************
 
//set the starting point for alll LEDs to be turned off
 
void setup()
 
{
 digitalWrite(LED2, LOW);
 digitalWrite(LED3, LOW);
 digitalWrite(LED4, LOW);
 digitalWrite(LED5, LOW);
 digitalWrite(LED6, LOW);
}
 
//****************************<wbr />******************************<wbr />**********************
 
//create a loop that alternates the LEDs down a row, and at the end of the loop the buzzer goes off.
 
void loop()
{
 for(int i = 0; i < 4; i++) {
  digitalWrite(LED2, HIGH);
  delay(500);
  digitalWrite(LED2, LOW);
  delay(500);
  digitalWrite(LED3, HIGH);
  delay(500);
  digitalWrite(LED3, LOW);
  delay(500);
  digitalWrite(LED4, HIGH);
  delay(500);
  digitalWrite(LED4, LOW);
  delay(500);
  digitalWrite(LED5, HIGH);
  delay(500);
  digitalWrite(LED5, LOW);
  delay(500);
  digitalWrite(LED6, HIGH);
  delay(500);
  digitalWrite(LED6, LOW);
  tone(buzOutPin, HIGH);
  delay(1000);
  noTone(buzOutPin);
}
}
<pre>