Using the SD Card instead of USB with USBHostMbed5

Using Arduino Storage
1

I have an application that uses the library Arduino_USBHostMbed5.
The reading of files from USB works perfectly.
Since my Arduino GIGA + DISPLAY SHIELD has an Ethernet Shield with SD Card, I wish to use the SD Card instead of the USB pendrive.

Is it possible to convert the USB reading to SD reading ?

This is my sketch used to load a file from the USB and store the file to the SDRAM
(modified from the example from the library)

void loadToSDRAM(String filename, uint16_t *buffer, int rawWidth, int rawHeight) {
  String file = "/usb/" + filename + ".bin";
  char buff[32];
  file.toCharArray(buff, 32);
  long freadReturn = 0;
  FILE *dataFile = fopen(buff, "rb+");
  if (dataFile == NULL) {
    Serial.print("File not found...");
  } else {
    freadReturn = fread(buffer, sizeof(uint16_t), rawWidth * rawHeight, dataFile);
  }
  fclose(dataFile);
}
2

You would have to rewrite the library. Why would you want to use a soon to be discontinued unreliable device (SD) over a reliable device?
I think I heard that the next Raspberry Pi will NOT have the SD card anymore.

3

There is not a specific reason, but I can mention the following:

  1. The SD reader is included in the Ethernet shield (I use the cable, not the wifi)
  2. The only pendrive I can use is an old Lexar 500 MB... very old ... other pendrive of 2 or 8 or 16 GB do not work and I can not understand way. All the pendrive tested are FAT32 formatted, but only the Lexar 500 MB works.
4

I think you have to format the larger drives using exFat.

exFAT has been adopted by the SD Association as the default file system for SDXC and SDUC cards larger than 32 GB.

exFAT is the ideal file system for USB flash drives . It doesn't have the 4GB file size limit and it's compatible with most Windows and Mac operating systems. Older operating systems might require an update to properly read and write to a USB drive with an exFAT file system.

5

Thanks a lot for the important info ! :hugs: