or if you don't want to use a transistor connect a speaker(or a piezo buzzer) between Arduino pin 10 and GND. Now the code part:
/*
* It sends a square wave of the appropriate frequency to the piezo, generating
* the corresponding tone.
*
* The calculation of the tones is made following the mathematical
* operation:
*
* timeHigh = period / 2 = 1 / (2 * toneFrequency)
*
* where the different tones are described as in the table:
*
* note frequency period timeHigh
* c 261 Hz 3830 1915
* d 294 Hz 3400 1700
* e 329 Hz 3038 1519
* f 349 Hz 2864 1432
* g 392 Hz 2550 1275
* a 440 Hz 2272 1136
* b 493 Hz 2028 1014
* C 523 Hz 1912 956
*
*
*/
/* Header File*/
#include<util/delay.h>
/* Global Variables*/
int speakerPin = 10; //Speaker is connected to DIGITAL PIN 10 on Arduino
int length = 11; //The number of notes in the song
char notes[] = "ccggaagffeeddc "; //These are the notes for tune "HAPPY BIRTHDAY"
int beats[] = { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 4 }; //(beats*tempo) signifies duration for which a particular note is played
int tempo = 280; //tempo specifies the speed at which the signal is played.
//To increase the speed, decrease the value of tempoand vice versa
/* Function Definitions*/
/*
This function generates a tone of frequency
specified by playNote function.
*/
void playTone(int tone, int duration)
{
for (long i = 0; i < duration * 1000L; i += tone * 2)
{
digitalWrite(speakerPin, HIGH);
_delay_us(tone);
digitalWrite(speakerPin, LOW);
_delay_us(tone);
}
}
/*
This functions reads one note at a time,
determines the T_HIGH(high time) corresponding to
note. for example: 'c' corresponds to a frequency
of 261Hz. Thus time period, T=1/261=3830usec. For
simplicity, we consider duty cycle of 50%.
T_HIGH=T_LOW=T/2
*/
void playNote(char note, int duration)
{
char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' };
int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 };
// play the tone corresponding to the note name
for (int i = 0; i < 8; i++)
{
if (names[i] == note)
{
playTone(tones[i], duration);
}
}
}
void setup()
{
pinMode(speakerPin, OUTPUT);
}
void loop()
{
for (int i = 0; i < length; i++) {
if (notes[i] == ' ')
{
_delay_ms(beats[i] * tempo); // rest
}
else
{
playNote(notes[i], beats[i] * tempo);
}
_delay_ms(tempo / 2); // pause between notes
}
}
The code is well commented and easy to understand.
Here, we define an array called "notes" and "beats":
char notes[] = "ccggaagffeeddc ";
int beats[] = { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 4 };
These are the notes for "Happy Birthday" song and beats basically signifies the duration of a particular note(the relation being, duration=beats*tempo).
The variable "length" specifies the length or the number of notes in the song.
int length = 11;
Here we also have two user defined functions called :
void playTone(int tone, int duration)
void playNote(char note, int duration)
The function playNote() reads one note at a time, determines the T_HIGH(high time) corresponding to note. for example: 'c' corresponds to a frequency of 261Hz. Thus time period, T=1/261=3830usec. For simplicity, we consider duty cycle of 50%.Thus T_HIGH=T_LOW=T/2=1915usec.
The function playTone() generates a tone of frequency specified by playNote function.
void setup() initialises pin 10 of Arduino as output.
void loop() takes one note at a time and sends it to function playNote().
One can also generate any sound/tone of choice just by changing 3 lines in the code.
1) char notes[]
2) int beats[]
3) int length
You can play "Twinkle Twinkle little stars" by setting
1) char notes[]={“ccggaagffeeddc “};
2) int beats[]= { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 4 };
3) int length=15;
I will post the video soon....!!!!
Till then enjoy....
*****************************************************************
The above code can also be implemented using 16-bit timer and counter of ATMEGA168/328. The timer is configured in fast PWM mode using WGM3:0= 15. For entire code
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