### Project 8 Passive buzzer

![](media/image-20251121164249024.png)

**1. Introduction**
We can use Arduino to make many interactive works of which the most commonly used is acoustic-optic display.

All the previous experiment has something to do with LED. However, the circuit in this experiment can produce sound. Normally, the experiment is done with a buzzer or a speaker while buzzer is more simpler and easier to use.

The buzzer we introduced here is a passive buzzer. It cannot be actuated by itself, but by external pulse frequencies. Different frequencies produce different sounds. We can use Arduino to code the melody of a song, which is quite fun and simple.

**2. Hardware required**

- Passive buzzer*1
- Arduino board *1
- Breadboard*1
- USB cable *1
- Breadboard jumper wire * 2

![](media/5.png)

**3. Connection for REV4**
Here we connect the passive buzzer to digital pin 8.

![](media/image-20251121165348151.png)

**4. Connection for 2560 R3**

![](media/image-20251121165448255.png)vv

**5. Sample Code**

```c
int buzzer=8;// select digital IO pin for the buzzer

void setup() 
{ 
	pinMode(buzzer,OUTPUT);// set digital IO pin pattern, OUTPUT to be output 
} 

void loop() 
{ 
    unsigned char i,j;//define variable
    while(1) 
    { 
    	for(i=0;i<80;i++)// output a frequency sound
    	{ 
            digitalWrite(buzzer,HIGH);// sound
            delay(1);//delay1ms 
            digitalWrite(buzzer,LOW);//not sound
            delay(1);//ms delay 
        } 
        for(i=0;i<100;i++)// output a frequency sound
        { 
            digitalWrite(buzzer,HIGH);// sound
            digitalWrite(buzzer,LOW);//not sound
            delay(2);//2ms delay 
        }
    } 
} 
```

**6. Result**
After downloading the program, buzzer experiment is finished. You can hear the buzzer beep.

![](media/image-20251121165751447.png)