I tried to add a string to a text file saved in "microSD" using "f_write" of "FATFS", but the writte

[t-oka]

Hello everyone in the community.

■What you are having trouble with :
→I tried to add a string to a text file saved in "microSD" using "f_write" of "FATFS", but the written content was not saved.

■Specific phenomenon:
→As shown in the PG below, the result of "f_write" is "FR_OK", and "byteswritten" also returns the number of written bytes, but no data is obtained even if "f_read" is performed.
When I checked the contents of the SD card, the written contents were not saved.
*The contents of the SD card were checked by stopping debugging after "f_close" processing.
*See PG below
*When I checked the contents of the file separately using only f_read, I was able to read it.

■Environment:

・Windows

・STM32CubeIDE_1.12.1

・nucleo-f207zgt6

・C language

■PG

static const char* filename = "test.txt";

FATFS sDFatFs;

FIL myFile;

if (f_mount(&sDFatFs, "", 0) != FR_OK){

return;

}

if(f_open(&myFile, filename, FA_OPEN_ALWAYS | FA_WRITE | FA_READ) != FR_OK){

return;

}

uint32_t byteswritten, bytesread;

FRESULT res;

uint8_t wtext[] = "This is STM32 working with FatFs\r\n";

uint8_t rtext[100];

f_lseek(&myFile, f_size(&myFile));

res = f_write(&myFile, wtext, sizeof(wtext), (void *)&byteswritten);

f_printf(&myFile, wtext);

if((byteswritten == 0) || (res != FR_OK)) {

f_close(&myFile);

return;

}

f_sync(&myFile);

f_lseek(&myFile, 0);

f_read(&myFile, rtext, sizeof(rtext), (void *)&bytesread);

f_close(&myFile);

■SDIO

[t-oka]

"else if(__HAL_SD_GET_FLAG(hsd, SDIO_FLAG_TXUNDERR))" in the "HAL_SD_WriteBlocks" function in the "f_close()" process was returning an error.
The problem is not resolved.

[t-oka · Accepted solution]

原因：SDIOCLK clock divide factorのデータ送信速度がSDIOバスの速度よりも速かったため。
対応策：SDIOCLK clock divide factorを10→20に変更するとfcloseすることが出来て、ファイルに文字列が追記されるようになりました。