Hi there,
Not sure if it will help , But I have this working on the Expansion Board SD card.
also I’m attaching a BIN to drop on it with everything compiled.
HTH
GL 
PJ
// adapted from Raui Shanchez
// Xiao Esp32C3 , 32 gig SD , formatted Fat 32 with 32k sector size.
//
//
#include "FS.h"
#include "SD.h"
#include "SPI.h"
#define SS D2
void setup(){
Serial.begin(9600);
delay (2000);
Serial.println(); // only for mbed 2.9.x
Serial.println("Power ON \n "); // Let's BEGIN!!
Serial.println("Test program compiled on " __DATE__ " at " __TIME__);
Serial.println();
Serial.println("Processor came out of reset.");
Serial.println();
// pinMode(fspi->pinSS(), OUTPUT); //VSPI SS
// pinMode(hspi->pinSS(), OUTPUT); //HSPI SS
digitalWrite(SS, HIGH); // <-- Set CS pin HIGH to deselect
Serial.println("--------------");
Serial.println(SS);
Serial.println(MOSI); // master out, slave in
Serial.println(MISO); // master in, slave out
Serial.println(SCK); // clock
Serial.println("--------------");
if(!SD.begin(SS)){
Serial.println("Card Mount Failed");
return;
}
uint8_t cardType = SD.cardType();
if(cardType == CARD_NONE){
Serial.println("No SD card attached");
return;
}
Serial.print("SD 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");
}
uint64_t cardSize = SD.cardSize() / (1024 * 1024);
Serial.printf("SD Card Size: %lluMB\n", cardSize);
listDir(SD, "/", 0);
createDir(SD, "/mydir");
listDir(SD, "/", 0);
removeDir(SD, "/mydir");
listDir(SD, "/", 2);
writeFile(SD, "/hello.txt", "Hello ");
appendFile(SD, "/hello.txt", "World!\n");
readFile(SD, "/hello.txt");
deleteFile(SD, "/foo.txt");
renameFile(SD, "/hello.txt", "/foo.txt");
readFile(SD, "/foo.txt");
testFileIO(SD, "/test.txt");
Serial.printf("Total space: %lluMB\n", SD.totalBytes() / (1024 * 1024));
Serial.printf("Used space: %lluMB\n", SD.usedBytes() / (1024 * 1024));
}
void loop(){
delay (500);
}
//
void listDir(fs::FS &fs, const char * dirname, uint8_t levels){
Serial.printf("Listing directory: %s\n", dirname);
File root = fs.open(dirname);
if(!root){
Serial.println("Failed to open directory");
return;
}
if(!root.isDirectory()){
Serial.println("Not a directory");
return;
}
File file = root.openNextFile();
while(file){
if(file.isDirectory()){
Serial.print(" DIR : ");
Serial.println(file.name());
if(levels){
listDir(fs, file.name(), levels -1);
}
} else {
Serial.print(" FILE: ");
Serial.print(file.name());
Serial.print(" SIZE: ");
Serial.println(file.size());
}
file = root.openNextFile();
}
}
void createDir(fs::FS &fs, const char * path){
Serial.printf("Creating Dir: %s\n", path);
if(fs.mkdir(path)){
Serial.println("Dir created");
} else {
Serial.println("mkdir failed");
}
}
void removeDir(fs::FS &fs, const char * path){
Serial.printf("Removing Dir: %s\n", path);
if(fs.rmdir(path)){
Serial.println("Dir removed");
} else {
Serial.println("rmdir failed");
}
}
void readFile(fs::FS &fs, const char * path){
Serial.printf("Reading file: %s\n", path);
File file = fs.open(path);
if(!file){
Serial.println("Failed to open file for reading");
return;
}
Serial.print("Read from file: ");
while(file.available()){
Serial.write(file.read());
}
file.close();
}
void writeFile(fs::FS &fs, const char * path, const char * message){
Serial.printf("Writing file: %s\n", path);
File file = fs.open(path, FILE_WRITE);
if(!file){
Serial.println("Failed to open file for writing");
return;
}
if(file.print(message)){
Serial.println("File written");
} else {
Serial.println("Write failed");
}
file.close();
}
void appendFile(fs::FS &fs, const char * path, const char * message){
Serial.printf("Appending to file: %s\n", path);
File file = fs.open(path, FILE_APPEND);
if(!file){
Serial.println("Failed to open file for appending");
return;
}
if(file.print(message)){
Serial.println("Message appended");
} else {
Serial.println("Append failed");
}
file.close();
}
void renameFile(fs::FS &fs, const char * path1, const char * path2){
Serial.printf("Renaming file %s to %s\n", path1, path2);
if (fs.rename(path1, path2)) {
Serial.println("File renamed");
} else {
Serial.println("Rename failed");
}
}
void deleteFile(fs::FS &fs, const char * path){
Serial.printf("Deleting file: %s\n", path);
if(fs.remove(path)){
Serial.println("File deleted");
} else {
Serial.println("Delete failed");
}
}
void testFileIO(fs::FS &fs, const char * path){
File file = fs.open(path);
static uint8_t buf[512];
size_t len = 0;
uint32_t start = millis();
uint32_t end = start;
if(file){
len = file.size();
size_t flen = len;
start = millis();
while(len){
size_t toRead = len;
if(toRead > 512){
toRead = 512;
}
file.read(buf, toRead);
len -= toRead;
}
end = millis() - start;
Serial.printf("%u bytes read for %u ms\n", flen, end);
file.close();
} else {
Serial.println("Failed to open file for reading");
}
file = fs.open(path, FILE_WRITE);
if(!file){
Serial.println("Failed to open file for writing");
return;
}
size_t i;
start = millis();
for(i=0; i<2048; i++){
file.write(buf, 512);
}
end = millis() - start;
Serial.printf("%u bytes written for %u ms\n", 2048 * 512, end);
file.close();
}
Serial Output.
Power ON
Test program compiled on Apr 1 2024 at 10:08:13
Processor came out of reset.
--------------
4
10
9
8
--------------
SD Card Type: SDHC
SD Card Size: 30474MB
Listing directory: /
DIR : System Volume Information
FILE: test.txt SIZE: 1048576
DIR : gif
FILE: foo.txt SIZE: 13
Creating Dir: /mydir
Dir created
Listing directory: /
DIR : System Volume Information
FILE: test.txt SIZE: 1048576
DIR : mydir
DIR : gif
FILE: foo.txt SIZE: 13
Removing Dir: /mydir
Dir removed
Listing directory: /
DIR : System Volume Information
Listing directory: System Volume Information
Failed to open directory
FILE: test.txt SIZE: 1048576
DIR : gif
Listing directory: gif
Failed to open directory
FILE: foo.txt SIZE: 13
Writing file: /hello.txt
File written
Appending to file: /hello.txt
Message appended
Reading file: /hello.txt
Read from file: Hello World!
Deleting file: /foo.txt
File deleted
Renaming file /hello.txt to /foo.txt
File renamed
Reading file: /foo.txt
Read from file: Hello World!
1048576 bytes read for 2528 ms
1048576 bytes written for 2828 ms
Total space: 30454MB
Used space: 4MB
compiler output
FQBN: esp32:esp32:XIAO_ESP32C3
Using board 'XIAO_ESP32C3' from platform in folder: C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10
Using core 'esp32' from platform in folder: C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10
cmd /c if exist "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\partitions.csv" COPY /y "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\partitions.csv" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\partitions.csv"
cmd /c if not exist "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\partitions.csv" if exist "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\variants\\XIAO_ESP32C3\\partitions.csv" COPY "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\variants\\XIAO_ESP32C3\\partitions.csv" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\partitions.csv"
cmd /c if not exist "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\partitions.csv" COPY "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\tools\\partitions\\default.csv" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\partitions.csv"
cmd /c IF EXIST "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\bootloader.bin" ( COPY /y "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\bootloader.bin" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\sketch_mar16a_SD_Exp_c3.ino.bootloader.bin" ) ELSE ( IF EXIST "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\variants\\XIAO_ESP32C3\\bootloader.bin" ( COPY "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\variants\\XIAO_ESP32C3\\bootloader.bin" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\sketch_mar16a_SD_Exp_c3.ino.bootloader.bin" ) ELSE ( "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esptool_py\\4.5.1/esptool.exe" --chip esp32c3 elf2image --flash_mode dio --flash_freq 80m --flash_size 4MB -o "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\sketch_mar16a_SD_Exp_c3.ino.bootloader.bin" "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\tools\\sdk\\esp32c3\\bin\\bootloader_qio_80m.elf" ) )
esptool.py v4.5.1
Creating esp32c3 image...
**** EDIT Brevity ****
Successfully created esp32c3 image.
"C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10/tools/gen_esp32part.exe" -q "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8/partitions.csv" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8/sketch_mar16a_SD_Exp_c3.ino.partitions.bin"
cmd /c if exist "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8\\libraries\\Insights" "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10/tools/gen_insights_package.exe" "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8" sketch_mar16a_SD_Exp_c3.ino "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3"
cmd /c IF 0==1 COPY /y "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\openocd-esp32\\v0.11.0-esp32-20221026\\share\\openocd\\scripts\\board\\esp32c3-builtin.cfg" "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\debug.cfg"
cmd /c IF 0==1 COPY /y "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\tools\\ide-debug\\esp32c3.json" "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\debug_custom.json"
cmd /c IF 0==1 COPY /y "C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\2.0.10\\tools\\ide-debug\\svd\\esp32c3.svd" "D:\\Arduino_projects\\sketch_mar16a_SD_Exp_c3\\debug.svd"
Multiple libraries were found for "SD.h"
Used: C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10\libraries\SD
Not used: C:\Users\Dude\AppData\Local\Arduino15\libraries\SD
Not used: D:\Arduino_projects\libraries\SD
Using library FS at version 2.0.0 in folder: C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10\libraries\FS
Using library SD at version 2.0.0 in folder: C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10\libraries\SD
Using library SPI at version 2.0.0 in folder: C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10\libraries\SPI
"C:\\Users\\Dude\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\riscv32-esp-elf-gcc\\esp-2021r2-patch5-8.4.0/bin/riscv32-esp-elf-size" -A "C:\\Users\\Dude\\AppData\\Local\\Temp\\arduino\\sketches\\12EDFA38154FA8D69920B5DEB88B17A8/sketch_mar16a_SD_Exp_c3.ino.elf"
Sketch uses 288952 bytes (22%) of program storage space. Maximum is 1310720 bytes.
Global variables use 14276 bytes (4%) of dynamic memory, leaving 313404 bytes for local variables. Maximum is 327680 bytes.
"C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\tools\esptool_py\4.5.1/esptool.exe" --chip esp32c3 --port "COM3" --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size 4MB 0x0 "C:\Users\Dude\AppData\Local\Temp\arduino\sketches\12EDFA38154FA8D69920B5DEB88B17A8/sketch_mar16a_SD_Exp_c3.ino.bootloader.bin" 0x8000 "C:\Users\Dude\AppData\Local\Temp\arduino\sketches\12EDFA38154FA8D69920B5DEB88B17A8/sketch_mar16a_SD_Exp_c3.ino.partitions.bin" 0xe000 "C:\Users\Dude\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.10/tools/partitions/boot_app0.bin" 0x10000 "C:\Users\Dude\AppData\Local\Temp\arduino\sketches\12EDFA38154FA8D69920B5DEB88B17A8/sketch_mar16a_SD_Exp_c3.ino.bin"
esptool.py v4.5.1
Serial port COM3
Connecting...
Chip is ESP32-C3 (revision v0.3)
Features: WiFi, BLE
Crystal is 40MHz
MAC: a0:76:4e:3f:a3:88
Uploading stub...
SD_EXP_c3.zip (182.6 KB)