Introduction
In our past lesson, we learned how to use PWM waves to drive a passive buzzer to ring. In this lesson, we make a simple keyboard by applying a passive buzzer. Let’s get started!
Newly AddedComponents
Schematic Diagram
Build the Circuit
- For C Language Users
Command
1.Go to the folder of the code.
cd /home/pi/electronic-kit/for-raspberry-pi/c/Lesson_13_Button_Piano
2. Compile the code.
gcc 13_ButtonPiano.c -lwiringPi
3. Run the executable file.
sudo ./a.out
Now press the seven buttons, and the buzzer will emit the notes: DO, RE, MI, FA, SO, LA, TI. You can play a song with these seven buttons.
Code
1.#include <wiringPi.h>
2.#include <softTone.h>
3.#include <stdio.h>
4.
5.#define BuzPin 0
6.
7.const int Tone[] = {262,294,330,350,393,441,495};//define DO, RE, MI, FA, SO, LA, TI
8.int beat[] = {1,1,1,1,1,1,1};
9.const int Btn[] = {2,3,4,5,6,10,11};//define 7 buttons
10.
11.int main(void)
12.{
13. int i, j;
14.
15. if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
16. printf("setup wiringPi failed !");
17. return 1;
18. }
19.
20. if(softToneCreate(BuzPin) == -1){
21. printf("setup softTone failed !");
22. return 1;
23. }
24.
25. //set the buttons mode
26. for(int j=0;j<7;j++)
27. {
28. pinMode(Btn[j], INPUT);
29. }
30.
31. while(1){
32. //printf("Please press button to play the piano\n");
33. // Indicate that button has pressed down
34. for(i=0;i<7;i++)
35. {
36. if(digitalRead(Btn[i])==1)
37. {
38. delay(10);//Prevent the button' s vibration
39. if(digitalRead(Btn[i])==1)
40. {
41. softToneWrite(BuzPin, Tone[i]);
42. delay(beat[i]*250);
43. printf("1");
44. }
45. }
46. else
47. softToneWrite(BuzPin, 0);
48. if(i==7)
49. i=0;
50. }
51. }
52. return 0;
53.} Code Explanation7.const int Tone[] = {262,294,330,350,393,441,495}; 8.int beat[] = {1,1,1,1,1,1,1};
In the array Tone[], define the frequencies of DO, RE, MI, FA, SO, LA, TI and the number in beat[] refers to the beat of each note in this song(0.5s for each beat).26.for(int j=0;j<7;j++)
27.{
28.pinMode(Btn[j], INPUT);
29.}
Set the mode of all buttons to input mode in the for loop.34.for(i=0;i<7;i++)
35.{
36.if(digitalRead(Btn[i])==1)
37.{
38.delay(10);//Prevent the button’ s vibration
39.if(digitalRead(Btn[i])==1)
40.{
41.softToneWrite(BuzPin, Tone[i]);
42.delay(beat[i]*250);
43.printf(“1”);
44.}
45.}
Use a for loop to check all the buttons. When one button in array Btn[i] is detected to be pressed, the buzzer will respond to the corresponding note in array Tone[i].
46.else
47.softToneWrite(BuzPin, 0);
48.if(i==7)
49.i=0;
50.}
If no button is pressed, turn off the buzzer.
- For Python Language Users
Command
1.Go to the folder of the code.
cd /home/pi/electronic-kit/for-raspberry-pi/python
2. Run the code.
sudo python3 13_ButtonPiano.py
Now press the seven buttons, and the buzzer will emit the notes: DO, RE, MI, FA, SO, LA, TI. You can play a song with these seven buttons.
Code
1.import RPi.GPIO as GPIO
2.import time
3.
4.Buzzer = 17
5.BtnPin = [18,27,22,23,24,25,8,7]
6.
7.CL = [0, 131, 147, 165, 175, 196, 211, 248] # Frequency of Low C notes
8.CM = [0, 262, 294, 330, 350, 393, 441, 495] # Frequency of Middle C notes
9.CH = [1, 525, 589, 661, 700, 786, 882, 990] # Frequency of High C notes
10.
11.song = [ 0,CM[1],CM[2],CM[3],CM[4],CM[5],CM[6],CM[7] ]
12.beat = [ 1,1, 1, 1, 1, 1, 1, 1]
13.
14.def setup():
15. GPIO.setmode(GPIO.BCM)
16. for i in range(1, len(BtnPin)):
17. GPIO.setup(BtnPin[i],GPIO.IN)
18. GPIO.setup(Buzzer, GPIO.OUT)
19.
20.def loop():
21. global Buzz
22. while True:
23. #print ('\n Please playing piano...')
24. for i in range(1, len(BtnPin)):
25. if GPIO.input(BtnPin[i]) == 1:
26. Buzz = GPIO.PWM(Buzzer, song[i])
27. Buzz.start(50)
28. time.sleep(beat[i] * 0.25)
29. Buzz.stop()
30.
31.def destory():
32. Buzz.stop()
33. GPIO.output(Buzzer, 0)
34. GPIO.cleanup()
35.
36.if __name__ == '__main__': # Program start from here
37. setup()
38. try:
39. loop()
40. except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the child program destroy() will be executed.
41. destory() Code Explanation7.CL = [0, 131, 147, 165, 175, 196, 211, 248] # Frequency of Low C notes
8.CM = [0, 262, 294, 330, 350, 393, 441, 495] # Frequency of Middle C notes
9.CH = [1, 525, 589, 661, 700, 786, 882, 990] # Frequency of High C notes
These are the frequencies of each note. The first 0 is to skip CL[0] so that the number CL[1]–CL[7] corresponds to the CDEFGAB of the note.10.song = [ 0,CM[1],CM[2],CM[3],CM[4],CM[5],CM[6],CM[7] ] 11.beat = [ 1,1, 1, 1, 1, 1, 1, 1]
Define a section of music and the corresponding beats. The number in beat[] refers to the beat of each note in the song(0.5s for each beat).16.for i in range(1, len(BtnPin)):
17.GPIO.setup(BtnPin[i],GPIO.IN)
Set the mode of all buttons to input mode in the for loop.24.for i in range(1, len(BtnPin)):
25.if GPIO.input(BtnPin[i]) == 1:
26.Buzz = GPIO.PWM(Buzzer, song[i])
27.Buzz.start(50)
28.time.sleep(beat[i] * 0.25)
29.Buzz.stop()
Use a for loop to check all the buttons. When one button in array button[i] is detected to be pressed, the buzzer will respond to the corresponding note in array song[i].