# Passive buzzer
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Features of passive buzzer:
1、There is no vibration source inside the passive, so if you use a DC signal, you can't make it tweet. Must use 2k~5k square wave (pwm) to drive it
2、The sound frequency is controllable, and the effect of the sound spectrum can be made
3、In some special cases, a control port can be reused with LED

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![](././../../images_dir/1625016079/1.png)
![](././../../images_dir/1625016160/2.png)

<span style="font-size:14px;">Schematic diagram of buzzer module installation</span>

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**<span style="font-size:16px;">In this example, the system's own pwm drive is used to control the buzzer to sound</span>**

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Test script program driver_210519pwm_buzzerpwm_buzzer.sh
Test command:
1、Increase execution authority: chmod +x pwm_buzzer.sh
2、Execute the script program: ./ pwm_buzzer.sh 7 300000 150000，
   a)The first parameter (7): refers to the seventh pwm channel
   b)The second parameter (300000): Specify the frequency of pwm
      i.1000       1Mhz
      ii.10000      100Khz
      iii.100000     10Khz
      iv.1000000    1Khz
   c)The third parameter (150000): Specify the duty cycle of pwm
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![](././../../images_dir/1703141148/4.png)
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