ESP32 Forum

Posted: **Sat Jun 08, 2024 4:28 pm**

Hi,

i use an ESP32 with a 3.3Volt SD-Card-Modul for data logging of my power meter.
One of my main functions is this, which refreshes a day-sum-file.
File is saved to SD card.

My curent problem is, that after random time (sometimes weeks, sometimes month) the file system seems to get destroyed/corrupted. Files on SD Card then all have strange names like "!")$/§)" and are not readable anymore.

Here is the current code (please stay friendly... i am a beginner

Code: Select all

// Struct at the moment has just one value
// Will be more in final script, so don't wonder why i use a struct here please ;-)
struct data_s {
  double kwh;
};

//Parameters
//filename_tmp : e.g. "2024-06-08.bin"
//measuring_kwh: e.g. "0.45"
void refresh_daysum (const char* filename_tmp, double measuring_kwh) {

  struct data_s sum;
  File sumFile;

  if (SD.exists(filename_tmp)) {
    // Read out current value
    sumFile= SD.open(filename_tmp, FILE_READ);
    while (sumFile.available()) {
      sumFile.read((uint8_t *)&summe, sizeof(summe));
    }
    sumFile.close();

    // add new measuring to current value
    sum.kwh = sum.kwh + measuring_kwh;
    
  } else {
    // First measuring of the day
    sum.kwh = measuring_kwh;
  }

  // Question is, if this part of the code is bad.
  // Is it bad to delete the file and create it anew every time?
  // Would it be better for SD-life to keep the file and just refresh the value?
  SD.remove(filename_tmp);
  sumFile= SD.open(filename_tmp, FILE_WRITE);
  sumFile.write((uint8_t *)&summe, sizeof(summe));
  sumFile.close();
}

Is this function maybe cause of the SD-Card defect?

Another question:
Is it better / required to check if SD-Card-Reader is ready with SD.begin(pinNum) prior to saving data each time.
Or is it ok to just call SD.begin() in void Setup()

Thank you for your support.

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