SunFounder ESP32 User Manual

SunFounder ESP32 Starter Kit
File file = SD_MMC.open("/test.txt", FILE_WRITE);
if (!file) {
Serial.println("Failed to open file for writing"); // Print error␣
˓→message if file failed to open
return;
}
• Write data to the file
Write the text “Test file write” to the file. If the write operation is successful, it prints “File write
successful”; otherwise, it prints “File write failed”.
if(file.print("Test file write")) { // Write the message to the file
Serial.println("File write success"); // If write succeeds, print to␣
˓→serial
} else {
Serial.println("File write failed"); // If write fails, print to serial
}
• Close the file
Close the opened file. This ensures that any buffered data is written to the file and the file is properly
closed.
file.close(); // Close the file
• Open the root directory
Open the root directory of the SD card. If the directory fails to open, it prints “Failed to open directory”
and returns.
File root = SD_MMC.open("/"); // Open the root directory of SD card
if (!root) {
Serial.println("Failed to open directory"); // Print error message if␣
˓→directory failed to open
return;
}
• Print each file’s name and size
The loop starting with while (File file = root.openNextFile()) iterates over all the files in
the root directory, printing each file’s name and size to the serial monitor.
Serial.println("Files found in root directory:"); // Print the list of␣
˓→files found in the root directory
while (File file = root.openNextFile()) { // Loop through all the files in␣
˓→the root directory
Serial.print(" ");
Serial.print(file.name()); // Print the filename
Serial.print("\t");
Serial.println(file.size()); // Print the filesize
file.close(); // Close the file
}
3. This loop() function is an empty loop and does nothing in the current program. However, in a typical Arduino
program, this function would continuously loop over and execute the code within it. In this case, since all the
154 Chapter 1. For Arduino User

SunFounder ESP32 Specifications

General

Brand	SunFounder
Model	ESP32
Category	Controller
Language	English