1.2.2 Passive Buzzer¶
Introduction¶
In this project, we will learn how to make a passive buzzer play music.
Required Components¶
In this project, we need the following components.
It’s definitely convenient to buy a whole kit, here’s the link:
Name |
ITEMS IN THIS KIT |
LINK |
---|---|---|
Raphael Kit |
337 |
You can also buy them separately from the links below.
COMPONENT INTRODUCTION |
PURCHASE LINK |
---|---|
Schematic Diagram¶
In this experiment, a passive buzzer, a PNP transistor and a 1k resistor are used between the base of the transistor and GPIO to protect the transistor.
When GPIO17 is given different frequencies, the passive buzzer will emit different sounds; in this way, the buzzer plays music.
Experimental Procedures¶
Step 1: Build the circuit. (The Passive buzzer with green circuit board on the back.)
Step 2: Change directory.
cd ~/raphael-kit/c/1.2.2/
Step 3: Compile.
gcc 1.2.2_PassiveBuzzer.c -lwiringPi
Step 4: Run.
sudo ./a.out
The code run, the buzzer plays a piece of music.
Note
If it does not work after running, or there is an error prompt: "wiringPi.h: No such file or directory", please refer to Install and Check the WiringPi.
Code
#include <wiringPi.h>
#include <softTone.h>
#include <stdio.h>
#define BuzPin 0
#define CL1 131
#define CL2 147
#define CL3 165
#define CL4 175
#define CL5 196
#define CL6 221
#define CL7 248
#define CM1 262
#define CM2 294
#define CM3 330
#define CM4 350
#define CM5 393
#define CM6 441
#define CM7 495
#define CH1 525
#define CH2 589
#define CH3 661
#define CH4 700
#define CH5 786
#define CH6 882
#define CH7 990
int song_1[] = {CM3,CM5,CM6,CM3,CM2,CM3,CM5,CM6,CH1,CM6,CM5,CM1,CM3,CM2,
CM2,CM3,CM5,CM2,CM3,CM3,CL6,CL6,CL6,CM1,CM2,CM3,CM2,CL7,
CL6,CM1,CL5};
int beat_1[] = {1,1,3,1,1,3,1,1,1,1,1,1,1,1,3,1,1,3,1,1,1,1,1,1,1,2,1,1,
1,1,1,1,1,1,3};
int song_2[] = {CM1,CM1,CM1,CL5,CM3,CM3,CM3,CM1,CM1,CM3,CM5,CM5,CM4,CM3,CM2,
CM2,CM3,CM4,CM4,CM3,CM2,CM3,CM1,CM1,CM3,CM2,CL5,CL7,CM2,CM1
};
int beat_2[] = {1,1,1,3,1,1,1,3,1,1,1,1,1,1,3,1,1,1,2,1,1,1,3,1,1,1,3,3,2,3};
int main(void)
{
int i, j;
if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
printf("setup wiringPi failed !");
return 1;
}
if(softToneCreate(BuzPin) == -1){
printf("setup softTone failed !");
return 1;
}
while(1){
printf("music is being played...\n");
for(i=0;i<sizeof(song_1)/4;i++){
softToneWrite(BuzPin, song_1[i]);
delay(beat_1[i] * 500);
}
for(i=0;i<sizeof(song_2)/4;i++){
softToneWrite(BuzPin, song_2[i]);
delay(beat_2[i] * 500);
}
}
return 0;
}
Code Explanation
#define CL1 131
#define CL2 147
#define CL3 165
#define CL4 175
#define CL5 196
#define CL6 221
#define CL7 248
#define CM1 262
#define CM2 294
These frequencies of each note are as shown. CL refers to low note, CM middle note, CH high note, 1-7 correspond to the notes C, D, E, F, G, A, B.
int song_1[] = {CM3,CM5,CM6,CM3,CM2,CM3,CM5,CM6,CH1,CM6,CM5,CM1,CM3,CM2,
CM2,CM3,CM5,CM2,CM3,CM3,CL6,CL6,CL6,CM1,CM2,CM3,CM2,CL7,
CL6,CM1,CL5};
int beat_1[] = {1,1,3,1,1,3,1,1,1,1,1,1,1,1,3,1,1,3,1,1,1,1,1,1,1,2,1,1,
1,1,1,1,1,1,3};
The array, song_1[]
stores a musical score of a song in which beat_1[]
refers to the beat of each note in the song (0.5s for each beat).
if(softToneCreate(BuzPin) == -1){
printf("setup softTone failed !");
return 1;
}
This creates a software controlled tone pin. You can use any GPIO pin
and the pin numbering will be that of the wiringPiSetup()
function
you used. The return value is 0 for success. Anything else and you
should check the global errnovariable to see what went wrong.
for(i=0;i<sizeof(song_1)/4;i++){
softToneWrite(BuzPin, song_1[i]);
delay(beat_1[i] * 500);
}
Employ a for statement to play song_1.
In the judgment condition, i<sizeof(song_1)/4,“devide by 4” is
used because the array song_1[]
is an array of the data type of integer,
and each element takes up four bytes.
The number of elements in song_1
(the number of musical notes) is gotten
by deviding sizeof(song_1)
by 4.
To enable each note to play for beat * 500ms, the function
delay(beat_1[i] \* 500)
is called.
The prototype of softToneWrite(BuzPin, song_1[i])
is:
void softToneWrite (int pin, int freq);
This updates the tone frequency value on the given pin. The tone does not stop playing until you set the frequency to 0.