short FAT32_Dev_Read_Sector();

[john.broderick]

Hi again,

Hoping this is an easy question for some.

I am trying to use the FAT32 library for the first time.

Jump to my last post!

SDCARD = FAT32_Init(); returns a 0 which means it must be working.

I am trying to read the boot sector using FAT32_Dev_Read_Sector(0,dataBuffer[x]);
The system hangs if I add the [x] in a for loop.
i.e. It will not move past this function.

If I remove the [x] it moves forward but then my 512 byte buffer is all zeros.

Does anyone have any tips please?

I was really happy finding the FAT32 'read sector' now I just need it to work lol.

Pic32 MZ
16 Gig SD Card formatted with Win10 32k per cluster (Standard)

Thank you in advance,
John B

[radug]

Hi there,

I think you should try :

FAT32_Dev_Read_Sector(0, &dataBuffer[x]);

since the function is defined like this (buf is a pointer not a value):

short FAT32_Dev_Read_Sector(unsigned long s, char *buf);

PS dataBuffer is the pointer and is the same as &dataBuffer[0]

[john.broderick]

Thank you for your time radug.

I have tried it and all I get is the address of the databuffer.
If I look at 512 bytes at that address, I get the address 512 times or get the address + x 512 times.
The 512 bytes of the buffer are all zeros.

I believe the fat16 was similar except it worked fine.

"unsigned int Mmc_Read_Sector(unsigned long sector, char *dbuff);" //from the help file

i.e.

for (x=0; x<512; x++){
Mmc_Read_Sector(Boot_Sector,dataBuffer[x]); //Boot sector = 0
Write_Number(x,xpos,ypos,White);
} // etc etc it will give me 512 characters from boot sector.


The dbuff did not need to be a pointer and works fine as a char[512]

[radug]

Sorry but I'm confused ...
In your example, is dataBuffer an array of 512 pointers to buffers of 512 chars each (512 x 512 bytes) ????
If yes, then it is correct (but you should also increment the sector number, I guess).

As far as I can understand from the documentation, Mmc_Read_Sector reads 512 bytes to the given address at a time.

The function reads one sector (512 bytes) from MMC card.

[john.broderick]

Sorry to confuse you radug.


Jump to bottom post of mine.

[john.broderick]

OMG

Whilst testing my own initialisation on a 2Gig SD card today, 07/10/21, I thought I would try a 2Gig card formatted to FAT32 since the boot process is the same for small cards.
Of course it worked.

I then tried the FAT32_Dev_Read_Sector(0,dataBuffer); with zero init.
It worked.
So the so called FAT32 LIBRARY is a gimmick and only designed to work on small cards, not 16 or 32Gig.

One may as well stick to FAT16 if using small cards.

Very disillusioned.

[filip]

Hi,

The FAT32 library works on various 2,4,8,16 or 32 GB cards, can you tell me if you have tried to change the cluster size when formatting it ?

Regards,
Filip.