Chapter 22 Play SD card music
================================
In the previous study, we have learned how to use the SD card, and then we will 
learn to play the music in the SD card.

Project 22.1 SDMMC Music
---------------------------
In this project, we will read an mp3 file from an SD card, decode it through ESP
32-S3, and use a speaker to play it.

Component List
^^^^^^^^^^^^^^^
- ESP32-S3-WROOM x1
- GPIO Extension Board x1
- 830 Tie-Points Breadboard x1
- NPN transistor(S8050) x2
- Speaker x1
- Diode x1
- Resistor 1kΩ  x1
- Jumper Wire x4

Component knowledge
^^^^^^^^^^^^^^^^^^^^
:ref:`Speaker <cpn_audio_speaker>`
"""""""""""""""""""""""""""""""""""""

Connect
^^^^^^^^
Please note that before connecting the USB cable, please put the music into the 
SD card and insert the SD card into the card slot on the back of the ESP32-S3.

.. image:: img/connect/22.png

Sketch
^^^^^^^
**How to install the library**
In this project, we will use the ESP8266Audio.zip 
library to decode the audio files in the SD card, and then output the audio signal 
through GPIO. If you have not installed this library, please follow the steps 
below to install it. 
open :menuselection:`arduino --> Sketch --> Include library --> Add .zip Library`.

.. image:: img/software/22-1.png

In the new pop-up window, select :file:`Super_Starter_Kit_for_ESP32_S3/C/Libraries/ESP8266Audio.zip`. Then click “Open“.

.. image:: img/software/22-2.png

**Sketch_22.1_PlayMP3FromSD**

We placed a folder called "music" in :file:`Super_Starter_Kit_for_ESP32_S3/Sketches/Sketch_22.1_PlayMP3FromSD` User needs to copy this folder to SD card.

.. image:: img/software/22-3.png

Click upload.

.. image:: img/software/22-5.png

Compile and upload the code to the ESP32-S3 WROOM and open the serial monitor. 
ESP32-S3 takes a few seconds to initialize the program. When you see the message 
below, it means that ESP32-S3 has started parsing the mp3 in sd and started play
ing music through Pin.

.. image:: img/software/22-4.png

Code
^^^^^^
The following is the program code:

.. code-block:: C

    #include <Arduino.h>
    #include <WiFi.h>
    #include "FS.h"
    #include "SD_MMC.h"
    #include "AudioFileSourceSD_MMC.h"
    #include "AudioFileSourceID3.h"
    #include "AudioGeneratorMP3.h"
    #include "AudioOutputI2SNoDAC.h"

    #define SD_MMC_CMD 38 //Please do not modify it.
    #define SD_MMC_CLK 39 //Please do not modify it. 
    #define SD_MMC_D0  40 //Please do not modify it.

    AudioGeneratorMP3 *mp3;
    AudioFileSourceID3 *id3;
    AudioOutputI2SNoDAC *out;

    AudioFileSourceSD_MMC *file = NULL;

    // Called when a metadata event occurs (i.e. an ID3 tag, an ICY block, etc.
    void MDCallback(void *cbData, const char *type, bool isUnicode, const char *string)
    {
    (void)cbData;
    Serial.printf("ID3 callback for: %s = '", type);

    if (isUnicode) {
        string += 2;
    }
    
    while (*string) {
        char a = *(string++);
        if (isUnicode) {
        string++;
        }
        Serial.printf("%c", a);
    }
    Serial.printf("'\n");
    Serial.flush();
    }

    void setup()
    {
    WiFi.mode(WIFI_OFF); 
    Serial.begin(115200);
    delay(1000);
    SD_MMC.setPins(SD_MMC_CLK, SD_MMC_CMD, SD_MMC_D0);
    if (!SD_MMC.begin("/sdcard", true, true, SDMMC_FREQ_DEFAULT, 5)) {
        Serial.println("Card Mount Failed");
        return;
    }
    Serial.printf("Sample MP3 playback begins...\n");

    audioLogger = &Serial;
    file = new AudioFileSourceSD_MMC("/music/01.mp3");
    id3 = new AudioFileSourceID3(file);
    id3->RegisterMetadataCB(MDCallback, (void*)"ID3TAG");
    //out = new AudioOutputI2S();
    out = new AudioOutputI2SNoDAC();
    out->SetPinout(12,13,14);//Set the audio output pin, Only 14 were used
    out->SetGain(3.5);//Setting the Volume
    mp3 = new AudioGeneratorMP3();
    mp3->begin(id3, out);
    }

    void loop()
    {
    if (mp3->isRunning()) {
        if (!mp3->loop()) mp3->stop();
    } else {
        Serial.printf("MP3 done\n");
        delay(1000);
    }
    }