SPI/SDIO - MicroSD Card Module

 

ESP32 Handling Files with a MicroSD Card Module

Source: https://randomnerdtutorials.com/esp32-microsd-card-arduino/

There are two different libraries for the ESP32 (included in the Arduino core for the ESP32): the SD library and the SDD_MMC.h library.

If you use the SD library, you’re using the SPI controller. If you use the SDD_MMC library you’re using the ESP32 SD/SDIO/MMC controller. You can learn more about the ESP32 SD/SDIO/MMC driver.

    

 

Arduino program structure

Soure: https://github.com/arduino/ArduinoCore-avr/blob/master/cores/arduino/main.cpp

#include <Arduino.h>

// Declared weak in Arduino.h to allow user redefinitions.

int atexit(void (* /*func*/ )()) { return 0; }

// Weak empty variant initialization function.

// May be redefined by variant files.

void initVariant() __attribute__((weak));

void initVariant() { }

void setupUSB() __attribute__((weak));

void setupUSB() { }

int main(void)

{

init();

initVariant();

#if defined(USBCON)

USBDevice.attach();

#endif

setup();

for (;;) {

loop();

if (serialEventRun) serialEventRun();

}

return 0;

}