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Within the four bytes, the pair with the lowest index is routed to the left speaker and the other pair is routed to the right speaker.

Generating the square wave

Local working variables

Listing 3 declares three working variables. The variable named val specifies the amplitude of the square wave. You will see what the other twovariable are used for later.

Listing 3 . Local working variables.
int val = 8000;//amplitude value of square wave byte byteLow = 0;byte byteHigh = 0;

Set the frequency of the square wave

Listing 4 shows the beginning of a for loop that is used to populate the audio data array. Note that this for loop traverses the array in steps of two bytes per iteration. This will be important later when weexamine the code that populates the array.

Listing 4 . Set the frequency of the square wave.
for(int cnt = 0;cnt<melody.length; cnt+=2){ //Change this value to change the fundamental frequency.//8 results in 1000 Hz //16 results in 500 Hz//32 results in 250 Hz, etc.if(cnt % 8 == 0){ //Change signval = -val; }//end if

The amplitude of the square wave switches back and forth between val and -val on a regular basis. The value used with the modulus operator in the if statement in Listing 4 determines how often that switch will take place. If it switches every eight bytes at a samplingrate of 8000 samples per second, the resulting fundamental frequency will be 1000 Hz. The comments in Listing 4 indicate other possibilities.

Do the math: (8 bytes/switch)*(2 switches/cycle)*(1 samp/2 bytes)* (1 sec/8000 samp) = 0.001 sec/cycleor 1000 cycles/sec or 1000 Hz

Decompose val into two bytes

Listing 5 decomposes the 16 least significant bits (LSB) of val into a pair of 8-bit bytes, discarding the 16 most significant bits (MSB) of the 32-bit int value.

Listing 5 . Decompose val into two bytes.
byteLow = (byte)val;//discard all but 8 lsb byteHigh = (byte)(val>>8);//shift right 8 and discard all but 8 lsb

The first statement in Listing 5 uses a (byte) cast to discard the 24 MSB of a copy of val and to store the remaining eight LSB in the variable named byteLow . This does not modify the value actually stored in the variable named val .

The second statement in Listing 5 begins by shifting a copy of val 8 bits to the right, thereby discarding the eight LSB and keeping the remaining24 MSB of the original 32 bits. This operation extends the sign bit to the right in conjunction with the shift.

Then the second statement uses a (byte) cast to discard the 24 MSB of the same copy of val and to store the remaining eight LSB in the variable named byteHigh .

There is a more elegant, but much more cryptic way to do this, which I will show you in a future module. I'm using this approach at this time because itshould be easy for you to understand what is actually happening.

Populate the audio data array

Listing 6 assigns the values of byteHigh and byteLow to the elements in the audio data array in the required order described above . Recall that the for loop iterates through the array two bytes per iteration. Thus, each iterationproduces one audio sample.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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