Where should I discuss SD/MMC FAT issues?

[JD123]

I'm not going to turn this into a thread of me talking to myself, but I wanted to say that I put a 24LC16 on the pic and I'm now reading the directory table into memory, working on it and writing it back to the MMC without any problems. The PC now accepts the modified files with the correct file information from the MMC.

Reading out of the MMC to the I2C takes ~3 seconds for a 512 sector. I'll be getting it faster by coding for loading the 16 byte buffer on the I2C.

[skimask]

The PC now accepts the modified files with the correct file information from the MMC.

So it was the file size issue then?

Reading out of the MMC to the I2C takes ~3 seconds for a 512 sector. I'll be getting it faster by coding for loading the 16 byte buffer on the I2C.

Post some code. I'm sure there's a way to make it faster... It only took my code about 7-ish seconds to erase a full 24LC256 (32Kbytes), while displaying the current address on an LCD.

[JD123]

I'll post the code if you promise not to laugh. When I'm in the R&D phase my goal is to understand, not to write pretty code. All I'm doing right now is building a reference for dealing with the MMC when I make a final application.

I'm at work (work has nothing to do with PICs) and the files are at home. No internet at home (yes, I live in a cave... next-door to Osama) so it will be a day or two before I get it up. Most likely I'll have the code faster by then as tonight I'll probably change it to write the page buffer on the I2C memory. I started with the recommended 10ms delay after a write and once things were stable, I moved it to 5ms. Next step will be polling for busy for the shortest delays.

[skimask]

I'll post the code if you promise not to laugh.

The difference between R&D code and pretty code is....who cares...

Most likely I'll have the code faster by then as tonight I'll probably change it to write the page buffer on the I2C memory. I started with the recommended 10ms delay after a write and once things were stable, I moved it to 5ms. Next step will be polling for busy for the shortest delays.

5ms is max. write cycle time for the 24LC16 (byte or page).
You start writing 16 byte pages, and it should speed up by a factor of about 16, with the same 5ms delay after the 16 byte packet is sent out.

[JD123]

Oh, and yes, the issue about the PC not 'seeing' the complete file was the file size information at offset 28 in the directory table. What you said about flipping the size to LSB first works well.

For giggles and grins I formatted the MMC as FAT32 and tried to work with the FAT. Let's just say... NOT! I'll stick with FAT16 as long as I can. Does Vista allow FAT16 and or format media cards in FAT16? Thought I heard somewhere that FAT16 support was dropped.

[skimask]

For giggles and grins I formatted the MMC as FAT32 and tried to work with the FAT. Let's just say... NOT! I'll stick with FAT16 as long as I can. Does Vista allow FAT16 and or format media cards in FAT16? Thought I heard somewhere that FAT16 support was dropped.

In that document, it specifies the cluster count cutoff for determining if something is formatted in FAT12/16/32.
If FAT16 was dropped, I would infer that FAT12 would've been dropped, which means no more floppies at all.
If you read that document, FAT32 is easy to work with, just have to take heed of the differences. The thing that's a real pain is the long filename's that come with it. But if you ignore those and stick with 8.3, FAT32 is a piece of cake.

[BrianT]

http://www.mmca.org/compliance/buy_s...EDSD84-A43.pdf

Cheers
BrianT

[Acetronics2]

Hi, JD ( Pffffff !!!!)

If you're interested ... I've such a project with a 18F452 ... but Written In MikroC ...
not so far from Basic.

I do not know why, but I think you'll be Ok ...

Alain

PM me a mailBox address if needed ...

[JD123]

Hi Alain,

Thanks for the offer. I'll take you up on that. My next step is getting some intelligent information about adding files and making sure things like overwrites and PC compatibility are handled correctly.

BTW, I recognize you from RCG.

Gary
[email protected]
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