> For the complete documentation index, see [llms.txt](https://docs.idew.org/code-robotics/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.idew.org/code-robotics/references/robot-behaviors/producing-alerts.md). # Producing Alerts These custom functions for producing alerts use the [speaker](/code-robotics/references/physical-outputs/speaker-buzzer.md) and/or [LED light](/code-robotics/references/physical-outputs/led-light.md): * `singleBeep()` — produces a typical beep * `doubleBeep()` — produces two quick beeps * `longBeep()` — produces a longer beep * `playSong()` — plays a song one note at a time in order Be sure your app lists these global variables for the LED and speaker pin numbers **before** the `setup()` function: ```cpp int LED = 13; int speaker = 9; ``` Be sure your app sets the pin modes for the LED and speaker **within** the `setup()` function: ```cpp pinMode(LED, OUTPUT); pinMode(speaker, OUTPUT); ``` An alert can be used as feedback to a user when the robot's built-in D12 button is pressed. Alerts can also be useful as feedback to indicate when other events or conditions have occurred (such as: detecting an obstacle, reaching a destination, completing a task, etc.). You can modify these custom functions (e.g., change frequency and duration of sound, etc.) and/or create your own alert functions for different situations (e.g., alarm sound, distress signal, obstacle alert, success signal, etc.). ## singleBeep() The `singleBeep()` custom function produces a typical beep sound: ```cpp void singleBeep() { digitalWrite(LED, HIGH); tone(speaker, 3000); delay(200); digitalWrite(LED, LOW); noTone(speaker); } ``` ## doubleBeep() The `doubleBeep()` custom function produces two short, high-pitched beeps: ```cpp void doubleBeep() { for (int i=0; i < 2; i++) { digitalWrite(LED, HIGH); tone(speaker, 4000); delay(100); digitalWrite(LED, LOW); noTone(speaker); delay(100); } } ``` ## longBeep() The `longBeep()` custom function produces a longer, low-pitched beep: ```cpp void longBeep() { digitalWrite(LED, HIGH); tone(speaker, 1000); delay(750); digitalWrite(LED, LOW); noTone(speaker); } ``` ## playSong() You can also use the speaker to play simple music by playing a song one note at a time. Each note corresponds to a specific frequency played for a specific duration (such as: whole note, half note, quarter note, etc.). {% hint style="danger" %} **IMPORTANT:** Be aware that while the song is playing, the robot will **NOT** be able to perform other behaviors such as checking sensors, navigating, etc. {% endhint %} Playing a song requires a file named `notes.h` that defines the specific frequencies for each note on a piano keyboard. It also defines durations (in milliseconds) for a whole note, half note, quarter note, etc. based on a defined beat length (in milliseconds). If necessary, you can modify the beat length to speed up or slow down the song. {% hint style="success" %} **IMPORTANT:** To play a song, you need to know its specific sequence of piano notes (and their durations). You'll need to refer to sheet music or search online. {% endhint %} To play a song using the speaker, your robot app will need to: 1. Add `notes.h` as a separate tab (separate file) in your app 2. Add an `#include` statement for `notes.h` in your app 3. Add the `playNote()` custom function to play musical notes 4. Create a custom function named `playSong()` to call the `playNote()` function for each note (or rest) in the song in sequence. 5. Call the `playSong()` function to play the song #### STEP 1. Add `notes.h` as Separate Tab in App In your app, create a new blank tab named `notes.h`: * **Arduino Create Web Editor:** Click the tab with a drop-down icon, and select "New Tab." In the pop-up, enter `notes.h` as the name of the new tab, and click the **OK** button. * **Arduino IDE Desktop Editor:** Click the down arrow icon in the top-right corner of the code editor window, and then select "New Tab" in the drop-down list. A small dialog will appear at the bottom of the code editor window. Enter `notes.h` as the name of the new file, and click the **OK** button. Copy the code below, and paste it into the blank tab named `notes.h`: {% code title="notes.h" %} ```cpp // NEEDED TO PLAY SONG NOTE BY NOTE // add as new tab named "notes.h" // define beat length - can modify to speed up or slow down song #define beatLength 200 // milliseconds per beat // define length of each note #define WN beatLength*4 // whole note #define HN beatLength*2 // half note #define QN beatLength // quarter note #define EN beatLength/2 // eighth note #define SN beatLength/4 // sixteenth note // define frequency of each note on a piano keyboard #define Rest 0 #define noteC0 16 #define noteCs0 17 #define noteDb0 17 #define noteD0 18 #define noteDs0 19 #define noteEb0 19 #define noteE0 21 #define noteF0 22 #define noteFs0 23 #define noteGb0 23 #define noteG0 25 #define noteGs0 26 #define noteAb0 26 #define noteA0 28 #define noteAs0 29 #define noteBb0 29 #define noteB0 31 #define noteC1 33 #define noteCs1 35 #define noteDb1 35 #define noteD1 37 #define noteDs1 39 #define noteEb1 39 #define noteE1 41 #define noteF1 44 #define noteFs1 46 #define noteGb1 46 #define noteG1 49 #define noteGs1 52 #define noteAb1 52 #define noteA1 55 #define noteAs1 58 #define noteBb1 58 #define noteB1 62 #define noteC2 65 #define noteCs2 69 #define noteDb2 69 #define noteD2 73 #define noteDs2 78 #define noteEb2 78 #define noteE2 82 #define noteF2 87 #define noteFs2 93 #define noteGb2 93 #define noteG2 98 #define noteGs2 104 #define noteAb2 104 #define noteA2 110 #define noteAs2 117 #define noteBb2 117 #define noteB2 123 #define noteC3 131 #define noteCs3 139 #define noteDb3 139 #define noteD3 147 #define noteDs3 156 #define noteEb3 156 #define noteE3 165 #define noteF3 175 #define noteFs3 185 #define noteGb3 185 #define noteG3 196 #define noteGs3 208 #define noteAb3 208 #define noteA3 220 #define noteAs3 233 #define noteBb3 233 #define noteB3 247 #define noteC4 262 #define noteCs4 277 #define noteDb4 277 #define noteD4 294 #define noteDs4 311 #define noteEb4 311 #define noteE4 330 #define noteF4 349 #define noteFs4 370 #define noteGb4 370 #define noteG4 392 #define noteGs4 415 #define noteAb4 415 #define noteA4 440 #define noteAs4 466 #define noteBb4 466 #define noteB4 494 #define noteC5 523 #define noteCs5 554 #define noteDb5 554 #define noteD5 587 #define noteDs5 622 #define noteEb5 622 #define noteE5 659 #define noteF5 698 #define noteFs5 740 #define noteGb5 740 #define noteG5 784 #define noteGs5 831 #define noteAb5 831 #define noteA5 880 #define noteAs5 932 #define noteBb5 932 #define noteB5 988 #define noteC6 1047 #define noteCs6 1109 #define noteDb6 1109 #define noteD6 1175 #define noteDs6 1245 #define noteEb6 1245 #define noteE6 1319 #define noteF6 1397 #define noteFs6 1480 #define noteGb6 1480 #define noteG6 1568 #define noteGs6 1661 #define noteAb6 1661 #define noteA6 1760 #define noteAs6 1865 #define noteBb6 1865 #define noteB6 1976 #define noteC7 2093 #define noteCs7 2217 #define noteDb7 2217 #define noteD7 2349 #define noteDs7 2489 #define noteEb7 2489 #define noteE7 2637 #define noteF7 2794 #define noteFs7 2960 #define noteGb7 2960 #define noteG7 3136 #define noteGs7 3322 #define noteAb7 3322 #define noteA7 3520 #define noteAs7 3729 #define noteBb7 3729 #define noteB7 3951 #define noteC8 4186 #define noteCs8 4435 #define noteDb8 4435 #define noteD8 4699 #define noteDs8 4978 #define noteEb8 4978 ``` {% endcode %} #### STEP 2. Include `notes.h` File in App Next you need to include the `notes.h` file in your app code, similar to including a library. In the code editor, click the tab that contains your main app. Add this code statement at the beginning of your app code: ```cpp #include "notes.h" ``` #### STEP 3. Add Custom Function to Play Individual Note A custom function named `playNote()` will be used to play one musical note at a time. When calling the function, you'll need to include parameters for the note and its duration. Add the `playNote()` function **after** your `loop()` function: ```cpp void playNote(int note, int duration) { // variable names for notes and durations defined in "notes.h" tone(speaker, note, duration); delay(duration); } ``` The variable names for the notes and durations are defined in the `notes.h` file: * Each **note** on a piano keyboard is defined in `notes.h` with a variable name that represents a specific frequency. For example, `noteC4` is the variable name for "Middle C", which is defined as having a frequency of 262 Hertz. * Each **duration** (whole note, half note, quarter note, etc.) is defined in `notes.h` with a variable name that represent a specific duration. For example, `WN` is the variable name for a whole note, which is defined as 4 beats (which will be 800 milliseconds if each beat length is defined as 200 milliseconds). To play a note, your app code will need to call the `playNote()` function and list the defined variable names for the specific note and its duration within the parentheses. For example, to play a "Middle C" whole note: ```cpp playNote(noteC4, WN); ``` #### STEP 4. Create Custom Function to Play Song Note by Note To play a song, your app code will need to play each note of the song in order by calling the `playNote()` function separately for each note (or rest) in the song. You'll create a custom function named `playSong()` that will contain all the `playNote()` statements in sequence for your song. Add this blank `playSong()` function **after** your `loop()` function: ```cpp void playSong() { // add code to play each note of song in order using playNote()​ } ``` To play a specific song, you'll need to know how it would be played on a piano one note at a time: i.e., what are the specific notes and their durations (whole note, half note, etc.) Then you'll have to use the `notes.h` file to determine which variable names to list for the note (or rest) and its duration. Then you'll need to list a code statement for each note (and rest) to call the `playNote()` function. For example, here's what the code inside the `playSong()` function would need to be in order to play the beginning of the song "Twinkle, Twinkle Little Star": ```cpp void playSong() { // add code to play each note of song in order using playNote() // beginning of "Twinkle, Twinkle Little Star" playNote(noteC4, QN); playNote(noteC4, QN); playNote(noteG4, QN); playNote(noteG4, QN); playNote(noteA4, QN); playNote(noteA4, QN); playNote(noteG4, HN); playNote(noteF4, QN); playNote(noteF4, QN); } ``` {% hint style="info" %} **MULTIPLE SONGS:** If your app needs to play more than one song, create a separate custom function to play the notes for each song. Give each custom function a unique name, such as `playSong1()`, `playSong2()`, etc. {% endhint %} #### STEP 5. Call Custom Function to Play Song You can play your song by calling the `playSong()` function **within** another function (such as the `setup()`, `loop()`, or another custom function) depending on when the song should be played: ```cpp playSong(); ``` If you need the song to play faster or slower, you can change the value for the `beatLength` defined in the `notes.h` file. By default, `beatLength` has been set to `200` milliseconds. * If the song should be played **faster**, use a **lower** value for `beatLength`. * If the song should be played **slower**, use a **higher** value for `beatLength`. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. 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