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Altera_Forum
Honored Contributor
Honored ContributorReading the first sector of a CF card
I'm trying to read the first sector of a compact flash card. This is the boot sector and bpb of a fat filesystem. This sector has a lot of information about how the filesystem is(number of sectors, bytes per sector, sector per cluster, etc). The problem is that i cant read it. I can read the second sector. I'm using the compact flash component from this forum and the source code with modifications. This is the code for the test application:
/* This testapplication shall read the bpb*/
# include "system.h"# include "ideutils.h"# include <stdio.h>
int main(void)
{
char *egenstr = "0 0 0";
if (IDE_initialize()) {//We can do some after this
readCHS(egenstr); //trying to read first sector..
}
else
{
printf("Cannot initialize IDE device.\r");
}
IDE_deinitialize();
printf("\rgoodbye\r\r4");
return 0;
}wrote and verified 10 values successfully.
Identify Device:
serial number: 001705A0603R4656
firmware revision: Vdg 1.23
model number: SanDisk SDCFB-32
LBA mode supported
PIO mode supported: 4
device parameters:
# logical cylinders: 490
# logical heads: 4
# logical sectors/track: 32
LBA capacity = 62720 sectors
successfully wrote default parameters to IDE drive.
readCHS: cylinder: 0; head; 0; sector: 0
CHS = (0, 0, 0); numSectors: 1
timeout awaiting DRQ=1
error register: 0x10
timeout awaiting DRQ in readSectorsCHS()
DRQ not set in status reg in readSectorsCHS()
readCHS() failed.
goodbye2 Replies
Altera_ForumI think I solved it. There is no sector number 0. I was confused by the second sector, it didn't contain what I expected. This is what the second sector contained:
And it didn't look like the boot sector and bpb. Please correct me if I'm wrong. -Ole Kristian Tørresen0000: FA 33 C0 8E D0 BC 00 7C 8B F4 50 07 50 1F FB FC .3.....|..P.P... 0010: BF 00 06 B9 00 01 F2 A5 EA 1D 06 00 00 BE BE 07 ................ 0020: B3 04 80 3C 80 74 0E 80 3C 00 75 1C 83 C6 10 FE ...<.t..<.u..... 0030: CB 75 EF CD 18 8B 14 8B 4C 02 8B EE 83 C6 10 FE .u......L....... 0040: CB 74 1A 80 3C 00 74 F4 BE 8B 06 AC 3C 00 74 0B .t..<.t.....<.t. 0050: 56 BB 07 00 B4 0E CD 10 5E EB F0 EB FE BF 05 00 V.......^....... 0060: BB 00 7C B8 01 02 57 CD 13 5F 73 0C 33 C0 CD 13 ..|...W.._s.3... 0070: 4F 75 ED BE A3 06 EB D3 BE C2 06 BF FE 7D 81 3D Ou...........}.= 0080: 55 AA 75 C7 8B F5 EA 00 7C 00 00 49 6E 76 61 6C U.u.....|..Inval 0090: 69 64 20 70 61 72 74 69 74 69 6F 6E 20 74 61 62 id partition tab 00A0: 6C 65 00 45 72 72 6F 72 20 6C 6F 61 64 69 6E 67 le.Error loading 00B0: 20 6F 70 65 72 61 74 69 6E 67 20 73 79 73 74 65 operating syste 00C0: 6D 00 4D 69 73 73 69 6E 67 20 6F 70 65 72 61 74 m.Missing operat 00D0: 69 6E 67 20 73 79 73 74 65 6D 00 00 00 00 00 00 ing system...... 00E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00F0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 0190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 01A0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 01B0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 ................ 01C0: 01 00 04 03 60 E8 20 00 00 00 60 F4 00 00 00 00 ....`. ...`..... 01D0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 01E0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 01F0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 AA ..............U.- Altera_Forum
Hi
You are right. This is not the boot sector. From my experience, if you are using a FAT filesystem, you won't find the bpb at the actual first sectors. There are partition tables and other stuff before that. What I did was to read the first sectors until I found something that confirmed that this is the bpb, meaning the jumpBoot (starts with EB or E9) and also the last two bytes of the sector are 0x55 and 0xAA. I foudn the bpb at logical sector 32. Nir
