Cant write file to CD, MbedOS 6.6.0

Mbed OS Bugs
1

mbed_app.json

Summary

{
“target_overrides”: {
“NUCLEO_F103RB”: {
“target.printf_lib”: “minimal-printf”,
“target.components_add”: [“SD”],
“platform.minimal-printf-enable-floating-point”: false,
“platform.stdio-minimal-console-only”: true
}
}
}

Main.cpp

Summary 
#include "mbed.h"
#include <errno.h>
#include <stdio.h>
#include <functional>
#include <chrono>

#define BUFFER_MAX_LEN 10
#define FORCE_REFORMAT true

#include "SDBlockDevice.h"
BlockDevice *sd = SDBlockDevice::get_default_instance();

#include "FATFileSystem.h"
FATFileSystem fs("fs");
FILE *myLogFile;

int counter = 0;
FILE *nextLogFile(void)
{
    static unsigned int fileNumber = 0;
    char fileName[32];
    FILE *filePtr = NULL;
    do {
        if (filePtr != NULL)
        fclose(filePtr);
        sprintf(fileName,"/fs/log%04u.txt",counter++);
        filePtr = fopen(fileName,"r");
    } 
while (filePtr != NULL);
     filePtr = fopen(fileName,"w");
     return filePtr;
}

int main()
{
    int err = fs.mount(sd);

    if (err || FORCE_REFORMAT) {
        printf("formatting... \n");
        fflush(stdout);
        err = fs.reformat(sd);
        if (err) {
            printf("bad reform\n");
            error("error: %s (%d)\n", strerror(-err), err);
            return 1;
        }
        printf("done\n");
        fflush(stdout);
    }
    fs.mkdir("directory", 077);
    myLogFile = nextLogFile();
    if (!myLogFile) {
        printf("cant createFile\n");
        error("error: %s (%d)\n", strerror(err), -err);
        return 1; // probably want to exit the program in this situation
    }
    printf("File created\n");
        fflush(stdout);
while(true)
{     
}
}

Having troubles with creating Files in Mbed, few days earlier code worked - well, but now i can create folder by fs.mkdir(“directory”, 077);
but
filePtr = fopen(fileName,“w”);
return filePtr;
returns 0x0, what am i doing wrong?

2

Hi Wilton,

could you please provide some more details:
What version of mbed-os are you using?
Could you provide more of your code - surrounding context etc ?

That would possibly give more people a chance to help you.

Thanks
Anna