[sdfat] why chdir return an error while it works

Using Arduino Programming Questions
1

Hello
I am writting a example file. My goal is to save some measurements in json line format into a folder path as the following

/log/year/month/day/

then the log for today will be

/log/2024/7/5/log.jsonl

I have two problems and I will discribe the first with the SD card.

First, I have a function defineVolumeWorkingDirectory() which will define the Volume Working Directory

I have create antoher function goToVolumeWorkingDirectory() to move into the Volume Working Directory, where the log.jsonl file will be created to save the log (json format)

I am surpise to see that the file is create in /LOG/2024/7/5/log.jsonl and the log is saved there. But...

The sd.chdir() does not return me an error.

However, the sd.chdir(sd_pathLog) return false and the following text is printed

.. Failed to chdir the VWD

How can it be possible if the log.jsonl file is created with the content???

Is there a way to debug if(sd.chdir(sd_pathLog)) to try why it return false while the file is well created a the right location????

Update: if(sd.mkdir(sd_pathLog)) return true

2

Are you using SdFat.h?

3

Hello,
Yes, I do. But in that example, he chdit just one folder.
May be I should chdir one folder after each

chdir('log');
chdir(year);
chdir(month);
chdir(day);
4

Maybe two "slants"?

//log//year//month//day//
5

The date_time array is too small, may be corrupting the file path or some other variables.

char date_time[18];                     //1010-10-10 11:11:11

< edit > the infamous semi-colon after the if statement

432         bool b = sd.chdir(sd_pathLog);
433         if(b == false);
434         {
435           if(debug)
436           {
437             Serial.print(F(".. "));
438             Serial.println(F("failed to chdir the VWD"));
439           }
440           return -2;
441         }
6

Hello David,
Ho ye, shame on me. thanks for this

7

I solved my problem, but honestly I do not know how :slight_smile:

I corrected the @david_2018 observation, but I am not sure this cause the issue.

However, I modify this

int defineVolumeWorkingDirectory()
{
  DateTime now = rtc.now();
  int16_t yy = now.year();                                        // Save the year
  int16_t mm = now.month();                                       // Save the month
  int16_t dd = now.day();                                         // Save the day

  sprintf(sd_pathLog,"/LOG/%i/%i/%i/",yy,mm,dd);                  // sd_pathLog is a global variable

  return volumeWorkingDirectory(false);
}

to

int defineVolumeWorkingDirectory()
{

  sprintf(sd_pathLog,"/LOG/%i/%i/%i",y,m,d);                  // sd_pathLog is a global variable

  return volumeWorkingDirectory(false);
}

y,m and d are global variable used all around my code RtcInterval update thoses global variable at each loop()
I also removed the last / at sd_pathLog.

PS: I removed the function defineVolumeWorkingDirectory() and printf(sd_pathLog,"/LOG/%i/%i/%i",y,m,d); is now in checkVolumeWorkingDirectory(). In that way, after midnight, the log are saved into the next day folder.

8

The semicolon after the if statement on line 433 ends the if statement (in effect, if b is equal to false, then do nothing).
The bracketed code on lines 434 through 441 is executed unconditionally, regardless of the value of b.