Sound Samples

This code is a demonstration of how you can combine code concepts, hardware, and built-in functions to make something unique out of a speaker and a button.

Code

/* * Press a button to activate various sound effects */ int pressCount = 0; //track presses on button to change the effect //Function to check for button presses void checkPress(){ if(digitalRead(12)==LOW){ pressCount++; delay(200); } } void setup() { pinMode(A5, OUTPUT); //speaker pinMode(12, INPUT_PULLUP); //button } void loop() { checkPress(); //run the checkPress function //rising pitch if(pressCount == 1) { //if pressCount = 1, start the rising tone for (int i = 0; (i < 1200); i++) {//play tones 0-1199 tone(A5, i); delay(5); checkPress(); //run the function to see if button was pressed if(pressCount!=1){ //if button pressed again, break the 'for' loop break; } // end the second if statement } // end the for loop } // end the first if statement //random tones if(pressCount == 2){ tone(A5, random(1,1201)); //Play any tone between 0 and 1200 delay(50); //pressCount is checked every 50 milliseconds } //falling pitch if(pressCount == 3) { for (int i = 1300; i > 30; i--) {//play tones from 1300 down to 31 tone(A5, i); delay(5); checkPress();//run function again to check pressCount if(pressCount!=3){ //if button pressed again, break the for loop break; } } } int pitch = 1 ; //tone value as it rises and falls int scale = 10; //the speed of the change of pitch. //rising and falling pitch while(pressCount == 4) { checkPress(); pitch = pitch + scale; tone(A5, pitch); delay(5); if(pitch <= 0 || pitch >= 1200){ scale = -scale; } } int lowTone = 10; //starting place for a rising tone int highTone = 1800; //starting place for a sinking tone //Low pitch rises as high pitch falls while(pressCount == 5){ checkPress(); tone(A5,lowTone); delay(50); tone(A5,highTone); delay(50); highTone-=10;// subtract 10 from highTone lowTone+=10; // add 10 to lowTone //reset the tones if(highTone < 10){ highTone = 1500; } if(lowTone > 1800){ lowTone = 10; } } //Turn off the sounds and reset presses to 0 if(pressCount > 5){ noTone(A5); pressCount = 0; } } // (c) 2017 Let's Start Coding. License: www.letsstartcoding.com/bsdlicense

Challenges

How many can you complete? Change the code and hardware according to the challenges below. Upload your code to see the effect when you're finished. Complete a challenge? Check it off the list!

Add a new button that turns all of the tones off by setting pressCount = 0; .

Can you come up with a new sound effect to add to the samples?

Can you trigger your new sound effect using a combination of two buttons held down?
Use an 'if' statement and inside it use the && operators to combine two conditions into an 'and' format.

Videos

Read the Code Walkthrough Text (click to open)

The first step of this program is to create a global variable called checkPress. It will hold the number of times you press a button and use that number to trigger sound effects.

There is also a function created for this program- checkPress(). The job of checkPress is to make it easy to increase pressCount. As you'll see by playing with the program, it is not simple to make a very reactive button to switch between sound effects.

In the setup() function, you set the pinModes of your components.

The first job of the loop is to run the checkPress() function. At first, the button will be unpressed and pressCount will equal 0. Because of that, all of the other statements in the code are false and nothing happens.

Pressing the button quickly will be caught by checkPress, which is running thousands of times a second. When checkPress sees the LOW signal from the button, pressCount becomes one.

For pressCount == 1, you’re ranging through the tones 0 to 1200 with a delay of 5 milliseconds between. The variable ‘i’ is used for both counting up through the ‘for’ loop and for assigning the tone to the speaker. The for will loop 1200 times, taking about 6000 milliseconds total, and will play each tone from 0 to 1200 for 5 milliseconds.

You can see that the checkPress() function is run every time the for loop runs. Then an if statement inside the for loop checks to see if pressCount does not equal 1 anymore. When that is true, the 'break' command ends the for loop immediately and the computer skips down to the next line of code.

pressCount == 2 is picking a random tone every 50 milliseconds and playing it to the speaker. You don’t need to use a variable here, since random() is a built-in function. Because of the way an if statement works, the checkPress() is still called at the top of the loop between each play of a random tone. Any time you press the button, the pressCount will be incremented before the next random tone is played.

pressCount == 3 is another for loop, this one moving in the opposite direction from pressCount ==1 . Starting at a tone value of 1300, the tone will fall by 1 every 5 milliseconds, then run the checkPress() function. When the value of i is 31, or when the value of pressCount is no longer 3, the for loop will exit and check the if statement again.

pressCount == 4 requires some variables to work correctly, so you can create those variables right above the ‘while’ statement. This can be a good idea in complicated code- create the variables close to where you will use them. While pressCount == 4, the variable ‘pitch’ is going to increase by ‘scale’ amount each time the loop is run. The if statement inside the while loop checks to see if the tone has reached a maximum of 1200 or a minimum of 0. If that’s true, then the scale becomes negative, reversing the tone’s direction.

pressCount == 5 plays two alternating tones back-to-back. One is rising and the other is falling by the amount in the variable ‘scale’. It uses variables to track these two tones and you can create them right above the ‘while’ loop. You want to play lowTone, play highTone, then increase lowTone by 10 and decrease highTone by 10. Within the ‘while’ is an ‘if’ statement that checks the value of lowTone and highTone every loop. When the max or minimum is hit, the lowTone and highTone are reset. It will only occur once each time that the variables are reset, but lowTone and highTone will be exactly equal at some point!

pressCount can continue on forever, but you stop it after 5. To reset the count to 0 and stop the tone, you can use a simple ‘if’ statement. Always be sure to check for all numbers greater than 5. Why? Imagine pressCount = 5 and you press and hold the button longer than you should. pressCount may now equal 7! Since you haven’t planned for 7 to be a possible pressCount, your code won’t know what to do.

Concepts

New Concept: Combining Conditions with AND && and OR ||

Sometimes, you want to create the same outcome from two different actions. For example, you may want to turn on a fan if a room gets too warm or if there is smoke in a room. Rather than write two separate if statements, you can combine these conditions with a Boolean OR. It's simple- you simply type the first condition inside an if or while loop, then type the 'pipes' and type the second condition. After you've typed the conditions, you can close the condition portion of your loop. This can get complex when there are many parentheses involved, so remember the order of operations. The 'pipes' are found below the delete or backspace key on most keyboards.

In other cases, you may want to do an action only if two things are true at the same time. For example, you may want to turn off a light only when two buttons are pressed, but not either of the buttons alone. To combine conditions this way, you use the Boolean AND, which is two ampersands side by side: &&. Both conditions that you put in the statement must be true before the action runs.

New Concept: Not Equal To Comparator

You're probably familiar with most of the comparators you see in code- < , >, <=, >=, and = are all used in other fields. The not-equal-to comparator is more rare. When using this comparator in an if statement, the condition is true when the two things being compared are not equal.

This comparator is useful when you're not sure how a variable may change. Imagine you're holding a very precise level of light on a plant. You're measuring the light with a light sensor and you have an alarm to go off if the light level changes. You don't care if the light increases or decreases or the amount that the light changes- you just need to know it's changed. By using a != comparator comparing your reading and the perfect light value you need, an if statement will be true any time the light value doesn't match your perfect light value.

New Concept: It's All Building Blocks

Code is complex, but it's made up of simple parts. You've seen how to combine them creatively to get something new and sometimes unexpected to happen. By paying attention to the basics and breaking down your problems until they're small enough to solve, you can create some wonderful things with code!

Quiz

If you're having trouble, try to run a program that can help you find the answer.

1. If you use “&&” between two condition in an 'if' statement, what are you doing?

Checking that one or the other condition is true to run the statement.
Checking that both of the conditions are true to run the statement.
Checking that only the second condition is true.

2. What is the best way to build a complex program or piece of code?

Start at the top and go as fast as you can. Check the code when you think it’s finished.
Break the problem into pieces, building and testing it one piece at a time.
Build it chronologically like you want the program to run. Don’t skip any part or come back later.

Previous Lesson