SD card, weird behavior, need some experts to bring up some ideas

Other Hardware Storage
1

Hi guys,

I have read quite a few helpful topics in the forum but couldn't find anything to my case. So here we go with my first post.

I'm preparing some functions for a bigger software and part of it is to write data to sd card.

The particular code:

boolean writeSD_byte () {
 myFile = SD.open("byte.ini", FILE_WRITE);
  if (myFile) {
    Serial.print("...Writing...");
    for (long i=0;i<1000000;i++) {
      myFile.write(random(255));
    }
    myFile.close();
    Serial.print("done...");
  }
  else Serial.print("failed...");
}

Running on an arduino mega with ethernet shield and an 32GB sd micro sd.

Failure description:
The for loop is currently set to 100000. If I further increase the number to 1 million or 10 million, I never get the serial print done message and the file has 0 byte size.

I haven't set any other outputs on purpose as I was simulating the fast writing which will be used in the program later.
I'm wondering whether there is:

  • any cache which is used by the library which overflows
    -any problem with the sd card size which maybe cause the problem (btw. I manually created a file of 10 MB and reading was no problem)
    -any counter related to write() which reaches an invalid value
    -any limitation on write() without closing the file in between

Thanks and regards,
Enrico