Chapter 21 Read and Write the SDcard

An SDcard slot is integrated on the back of the ESP32-S3 WROOM. In this chapter we learn how to use ESP32S3 to read and write SDcard.

Project 21.1 SDMMC Test

Component List

  • ESP32-S3-WROOM x1

  • Type C USB Cable x1

  • Memory Card x1

Format SD card

Before starting the tutorial, we need to create a drive letter for the blank SD card and format it. This step requires a card reader and SD card. Please prepare them in advance. Below we will guide you to do it on different computer systems. You can choose the guide that matches your computer. Windows Insert the SD card into the card reader, then insert the card reader into the computer. In the Windows search box, enter “Disk Management” and select “Create and format hard disk partitions”.

../_images/format1.png

In the new pop-up window, find an unallocated volume close to 1G in size.

../_images/format2.png

Click to select the volume, right-click and select “New Simple Volume”.

../_images/format3.png

Click Next.

../_images/format4.png ../_images/format5.png

You can choose the drive letter on the right, or you can choose the default. By default, just click Next.

../_images/format6.png

File system is FAT(or FAT32). The Allocation unit size is 16K, and the Volume label can be set to any name. After setting, click Next.

../_images/format7.png

Click Finish. Wait for the SD card initialization to complete.

../_images/format8.png

At this point, you can see the SD card in This PC.

../_images/format9.png

MAC Insert the SD card into the card reader, then insert the card reader into the computer. Some computers will prompt the following information, please click to ignore it.

../_images/format_mac1.png

Find “Disk Utility” in the MAC system and click to open it.

../_images/format_mac2.png

Select “Generic MassStorageClass Media”, note that its size is about 1G. Please do not choose wrong item. Click “Erase”.

../_images/format_mac3.png

Select the configuration as shown in the figure below, and then click “Erase”.

../_images/format_mac4.png

Wait for the formatting to complete. When finished, it will look like the picture below. At this point, you can see a new disk on the desktop named “SD”.

../_images/format_mac5.png

Connect

Connect ESP32-S3 to the computer using the USB cable.

../_images/connect1.png

Before connecting the USB cable, insert the SD card into the SD card slot on the back of the ESP32-S3.

Sketch

Sketch_21.1_SDMMC_Test

../_images/21.1.png

Compile and upload the code to ESP32-S3-WROOM, open the serial monitor, and press the RST button on the board. You can see the printout as shown below. The program will eventually add two text files to the sd card. You can open them with a card reader. There will be “Hello World!” text in foo.txt

../_images/21.11.png

Code

The following is the program code:

#include "sd_read_write.h"
#include "SD_MMC.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.

void setup(){
    Serial.begin(115200);  // Initialize serial communication
    SD_MMC.setPins(SD_MMC_CLK, SD_MMC_CMD, SD_MMC_D0);  // Set SD card pins
    if (!SD_MMC.begin("/sdcard", true, true, SDMMC_FREQ_DEFAULT, 5)) {  // Mount SD card
    Serial.println("Card Mount Failed");
    return;
    }
    uint8_t cardType = SD_MMC.cardType();  // Get SD card type
    if(cardType == CARD_NONE){
        Serial.println("No SD_MMC card attached");
        return;
    }

    // Print SD card type
    Serial.print("SD_MMC Card Type: ");
    if(cardType == CARD_MMC){
        Serial.println("MMC");
    } else if(cardType == CARD_SD){
        Serial.println("SDSC");
    } else if(cardType == CARD_SDHC){
        Serial.println("SDHC");
    } else {
        Serial.println("UNKNOWN");
    }

    // Print SD card size
    uint64_t cardSize = SD_MMC.cardSize() / (1024 * 1024);
    Serial.printf("SD_MMC Card Size: %lluMB\n", cardSize);

    listDir(SD_MMC, "/", 0);  // List root directory contents

    createDir(SD_MMC, "/mydir");  // Create a directory
    listDir(SD_MMC, "/", 0);  // List root directory again

    removeDir(SD_MMC, "/mydir");  // Remove the created directory
    listDir(SD_MMC, "/", 2);  // List root directory with depth 2

    writeFile(SD_MMC, "/hello.txt", "Hello ");  // Write to a file
    appendFile(SD_MMC, "/hello.txt", "World!\n");  // Append to the file
    readFile(SD_MMC, "/hello.txt");  // Read the file

    deleteFile(SD_MMC, "/foo.txt");  // Delete a file (if it exists)
    renameFile(SD_MMC, "/hello.txt", "/foo.txt");  // Rename a file
    readFile(SD_MMC, "/foo.txt");  // Read the renamed file

    testFileIO(SD_MMC, "/test.txt");  // Perform I/O test on a file

    // Print total and used space on the SD card
    Serial.printf("Total space: %lluMB\r\n", SD_MMC.totalBytes() / (1024 * 1024));
    Serial.printf("Used space: %lluMB\r\n", SD_MMC.usedBytes() / (1024 * 1024));
}

void loop(){
delay(10000);  // Wait for 10 seconds
}