FAT32 code for MultiMedia Cards

Tomi · Joined: 11 Aug 2005 Posts: 10

Just removed the dust from my old FAT32 code. Maybe it will be useful for somebody... See notes in EX_ file.

So the header file (MyMMCFat32.h):

Bart · Joined: 12 Jul 2005 Posts: 49

Is there someone who has this working for an 18F4550 ?

Thanks.

PicFan · Posted: Fri Oct 06, 2006 3:04 pm

Tomi,

Thanks for posting the code, I'm having a little difficulty when compiling.

Can't seem to find two functions that are being called:
ResetPorts()
DoIdle()

Do these functions provide any critical support for the overall MMC or FAT usage?

Best Regards,
PicFan

raus · Joined: 12 Dec 2006 Posts: 1

Hi!!

Has anyone tested this code in PIC18F6720? I'm very interested in it. If anybody knows more about it, or a similar code for FAT32 and SD/MMC cards, please help me Laughing

Thanks in advance, at least you have read this ;)

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

I have a SD/MMC file system that will support this and other 18F series PICs. http://www.brushelectronics.com/index.php?page=software#SDFS

In addition you will find multiple working reference schematics on the projects page.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

sovalye · Joined: 08 Feb 2007 Posts: 1

Hey Tomi
You are a big man.
Thank you very much to send this code.

With this code we will have a filesystem inside PIC.

I will try it. I also want to make it USB Mass storage device. Can we use this code for it, is it similar?

pokemontro · Joined: 15 Feb 2007 Posts: 2

Hey! It's amazing!
I need to use a Pen Drive (Mass Storage Device) and mount a archive with all data processed using a PIC device. Have you a example code about this? It's possible?

Thanks!

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

pokemontro · Joined: 15 Feb 2007 Posts: 2

Well,

But use a Pen Drive is more pratic to me. I know that to use a SD/MMC card is more easy.
If the implementation of Pen Drive is possible, I can use this. You know how I use that? You have any example or a place to download it?

Thanks.

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

Here is the link to the USB host controller:

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3639

You will need to develop your own low level driver to interface with the FAT file system.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

Mattr0 · Joined: 27 Mar 2005 Posts: 30

I am having a problem getting this to work. The problem is it will not compile due to the SSPBUF on the MMC routines. I tried to switch this to SPI_WRITE read etc. but I am having no luck. The FAT16 driver on forum works without a problem but I don't know how to write a file to that one. This one look to be better if I could get it to work. I am using a 18F4620 with compiler ver 4.025

Thanks

void MMCOut(char indata)
{
char i;
SSPBUF=indata; //not defined
while (!BF);
i = SSPBUF;
}

Tomi · Joined: 11 Aug 2005 Posts: 10

Sorry for that, always include "my6720.h" what looks like this:

Tomi · Joined: 11 Aug 2005 Posts: 10

Some people have problems using my FAT32 code especially with undefined functions.
You can find below some short explanations.

1. The clock functions. I use a Ricoh clock chip to get a real time clock because my target circuit is a data logger.
InitClockInt() funtion sets up the INT_A output of the chip as 32768Hz clock output so it is called only once in early main() in initialization section. It is then connected to the PIC's TIMER1 input to get an interrupt in every 2 seconds. The logger has battery-backup solar power supply so I have to use Sleep() to minimize the power consumption. The target board is waked up in every 2 seconds.

2. ReadClock() functions reads out the current date and time and stores the data in a standard "struct tm" structure. The definition:

spiken · Joined: 29 Mar 2007 Posts: 1

Hi,

I found some strange code in fopen and remove. Why do you need
&& nextcluster != 0? The nextcluster can be zero when it's initialized.
Also, can nextcluster be zero when the actcluster is anything else than 0 or 0x0FFFFFFF?

int32 actsector,actcluster,nextcluster;
....
....
actcluster = ComposeCluster(f);
while (actcluster != 0x0FFFFFFF && nextcluster != 0) {
nextcluster = GetNextCluster(actcluster);
if (nextcluster == 0x0FFFFFFF || nextcluster == 0) break;
actcluster = nextcluster;
}

Tomi · Joined: 11 Aug 2005 Posts: 10

It is only an error check. The cluster number in this case never could be zero because it is a part of an existing file what you want to open or delete. In this case every cluster number could be either a legal number (the next cluster number) or 0x0FFFFFFF (last cluster; end of file).
A zero in the cluster chain of an existing file means a broken file (otherwise zero means "cluster is not in use"). It could happens when the sector content is already written to, but the FAT is not updated yet; for example because the card is pulled out by the user under the update (in the logger I write momentary wind in every 2 seconds so the probability is high; keep in mind that we don't have enough RAM space in the PIC to keep the FAT and data sector in the RAM at same time; we have to swap the RAM contents freqently).