hdkn wrote on Wednesday, May 15, 2019:
Hello Hein,
Thanks for replying.
Regarding alignment. The file write/read test functions simply pass the whole data buffer directly to the ff_stdio functions. The buffer address is aligned and I use byte sizes of N x 1024. The calling code looks something like:
/* Allocate the file buffer at a high-enough address. */
pcFileBuffer = ( void * ) 0x10000000; // 256M
...
xWritten = ff_fwrite( pcFileBuffer, 1, xSize, xFp );
According to the dev board’s manual: “This 4-bit data interface can sustain burst read operations at up to 50 MHz for a throughput of 25 MBps.”
I will check the clock and other settings today.
I am using alt_sdmmc.c, but the one from HWLib 18.0 because the one under the CORTEX_A9_Cyclone_V_SoC_DK demo lacked basic features like getting the max sectors, which is needed for initializing FF_Disk.
I do use alt_sdmmc_read() and alt_sdmmc_write(). I think that’s all they have for general read/write. I pass ulSectorCount x 512 for the size. Here’s what I use in prvFFWrite():
void *pvDest = ( void * ) ( ulSectorNumber * 512UL );
xResult = alt_sdmmc_write( &xCardInfo, // card_info
pvDest, // dest
( void * ) pucBuffer, // src
ulSectorCount * 512UL ); // size
Forgot to mention that the card was formatted with FF_SDDiskFormat() just to be complete.
I am attaching the relevant source files for your reference.
Hideki