Need Help!- SD card MBR

[The Blight]

I don't know if this is the best place to post, but I will give it a try.

I'm programming a PIC to read from a SD card (FAT16), and I have gotten it to send and recieve the information I "want". The problem is that the 32mb card sends the correct information from the MBR (The LBA of the first partition), but my 256mb card sends useless bs (I have tried reading partition entry 1,2,3 and 4). Both cards have a MBR, and I have located how much of an offset there is on both cards, but I can only find this information in the MBR of one card (32). Whats up with the other one?

I can't belive windows uses CHS.

PS. I have tried formating the card again, but I still can't get the correct LBA for the first partition.

Edit: Checked the MBR of the 256 card in WinHEX. Seems like the CHS addressing is also corupted. The LBA says there are 778135908 secotors before the first sector in the first partition.

Edit2: Found out that when reading the MBR in WinHEX it just pulls out the data from the partition boot record. Useless.

[keebler303]

Have you tried more applicable forums? Like the ones at htsoft.com, microchip, etc?

I have seen SD card stuff there before but have never played with it.

Good Luck
Matt

[Eurisko]

Try dskprobe.exe , a free disk sector editor available from Microsoft.

http://www.microsoft.com/downloads/d...displaylang=en

I've used a PIC to play 16 bit wav files from an SD card, but the cards were 1 or 2 GB and FAT32 format.
Haven't taken the time to learn FAT16.

EDIT:
Just remembered that I had some format issues. Try formatting the card in a digital camera, then read the sectors with dskprobe.

Then format the card in Windows and read the sectors again. I must be getting old, but I can't remember which formatting method solved the problem

[The Blight]

Well I have gotten every other card to read the correct data, so it is working. But I found an interesting topic in another forum where someone pointed out that the MBR might be in the next sector. I can't remember why, and I have not tested it yet, so I don't know if it works. For now I will just ignore it.

Eurisko, that might solve the problem if the camera can create a good MBR, or removes it all together. The problem might in fact be that this card was formatted on a camera that makes a buggy MBR.

But I have to say that getting the SD card to work is easier then I anticipated. FAT (when done correctly) is also easy.