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Using fat.c
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skelzer



Joined: 21 Apr 2016
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Using fat.c
PostPosted: Tue Apr 26, 2016 5:58 am     Reply with quote

Hello there,

Could I get any example using the library fat.c where the SD is written via SPI?(http://www.ccsinfo.com/forum/viewtopic.php?t=53787)

I usually like to take my time reading and experimenting, but this time I'm in a bit of a hurry, so... Embarassed


Thank you very much.
temtronic



Joined: 01 Jul 2010
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PostPosted: Tue Apr 26, 2016 6:46 am     Reply with quote

well first place to look is in the 'code library' here...
or general search 'SD'...
also
You MUST use a 3 volt( 'L' series) PIC OR proper logic level translation between the 3 volt SD card and a 5 volt PIC. If you don't .it won't work correctly !!


Jay
skelzer



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PostPosted: Tue Apr 26, 2016 7:43 am     Reply with quote

temtronic wrote:
well first place to look is in the 'code library' here...
or general search 'SD'...
also
You MUST use a 3 volt( 'L' series) PIC OR proper logic level translation between the 3 volt SD card and a 5 volt PIC. If you don't .it won't work correctly !!


Jay


Hey, thanks for the quick reply Smile


I've tried to use the search and won't return any results when I use SD as the keyword. Anyways, thanks for the tip about the code library, found a few threads there that are being really helpful Smile.

And yes, I'm using a 3 volt PIC, I don't want to fry the SD! Smile

The thing is, I won't have any way to test this until thursday, and it's due friday (Don't you guys love when your deadlines are completely ridiculous? I totally do :D ) so I'm trying to put together a code that'll work quick.

Here I'm trying (or failing hard) to create a file called log1.txt, would this work?


Code:

         #define MMCSD_PIN_SCL     PIN_B10 //o
         #define MMCSD_PIN_SDI     PIN_B11 //i
         #define MMCSD_PIN_SDO     PIN_B12 //o
         #define MMCSD_PIN_SELECT  PIN_B13 //o
main()
{
mmcsd_init()
char filename[]="log1.txt";

fat_init();

mk_file(filename);

mmcsd_write_byte(0, filename);
}
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Tue Apr 26, 2016 8:19 am     Reply with quote

Comments in line:
Code:

         #define MMCSD_PIN_SCL     PIN_B10 //o
         #define MMCSD_PIN_SDI     PIN_B11 //i
         #define MMCSD_PIN_SDO     PIN_B12 //o
         #define MMCSD_PIN_SELECT  PIN_B13 //o
//These need to be declared _before_ you load the mmc library.

main()
{
    char filename[]="log1.txt";
    //keep to the C standard and declare variables at the start of sections
    FILE file_stream; //You need a file variable created.

    mmcsd_init(); //semi-colon missing

    fat_init();

    mk_file(filename);
    //Now you need to open the file....
    //mmcsd_write_byte(0, filename);
    //No. You write to the open [u]file[/u].
    fatopen(filename,"w", file_stream);
    fatputc('\0',file_stream); //This now writes the 0 byte to the file
    fatclose(file_stream); //then you must close the file

    while (TRUE)
       ;
    //
}


Also general comment you must have the pull-up resistors on some of the SD lines. required to ensure it wakes in the right mode, and also recommended to speed the rising edges.
skelzer



Joined: 21 Apr 2016
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PostPosted: Tue Apr 26, 2016 8:36 am     Reply with quote

Ttelmah wrote:
Comments in line:
Code:

         #define MMCSD_PIN_SCL     PIN_B10 //o
         #define MMCSD_PIN_SDI     PIN_B11 //i
         #define MMCSD_PIN_SDO     PIN_B12 //o
         #define MMCSD_PIN_SELECT  PIN_B13 //o
//These need to be declared _before_ you load the mmc library.

main()
{
    char filename[]="log1.txt";
    //keep to the C standard and declare variables at the start of sections
    FILE file_stream; //You need a file variable created.

    mmcsd_init(); //semi-colon missing

    fat_init();

    mk_file(filename);
    //Now you need to open the file....
    //mmcsd_write_byte(0, filename);
    //No. You write to the open [u]file[/u].
    fatopen(filename,"w", file_stream);
    fatputc('\0',file_stream); //This now writes the 0 byte to the file
    fatclose(file_stream); //then you must close the file

    while (TRUE)
       ;
    //
}


Also general comment you must have the pull-up resistors on some of the SD lines. required to ensure it wakes in the right mode, and also recommended to speed the rising edges.


First of all, thank you very much Ttelmah for being so thorough, this helps a lot, as I don't even have the IDE in the PC I'm using today, so I'm using notepad.

I think I have the basics down by now, will work on it tomorrow and hope everything works fine on Thursday (Praying to the gods of compilation now...)
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Tue Apr 26, 2016 9:24 am     Reply with quote

One warning. In the code library you will find three threads, including an SDHC modification, and a couple of fixes for faults in the standard SD driver. There is then an 'accrued' version at the start of the forum as a sticky (from electr0dave). Use this.
This fixes all the current bugs with the MMC driver and also gives support for cards over 2GB.
skelzer



Joined: 21 Apr 2016
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PostPosted: Wed Apr 27, 2016 2:02 am     Reply with quote

Ttelmah wrote:
One warning. In the code library you will find three threads, including an SDHC modification, and a couple of fixes for faults in the standard SD driver. There is then an 'accrued' version at the start of the forum as a sticky (from electr0dave). Use this.
This fixes all the current bugs with the MMC driver and also gives support for cards over 2GB.



Roger.


I could get my hands on the IDE earlier than I expected, tried this:

Code:
#include <main.h>
#define MMCSD_PIN_SCL     PIN_B10 //o
#define MMCSD_PIN_SDI     PIN_B11 //i
#define MMCSD_PIN_SDO     PIN_B12 //o
#define MMCSD_PIN_SELECT  PIN_B13 //o
#include <mmcsd.h>
#include <fat.c>


void main()
{
      char filename[]="log1.txt";
      FILE file_stream;
      mmcsd_init();
      fat_init();
      mk_file(filename);
      fatopen(filename,"w",file_stream);
      fatputc('\0',file_stream);
      fatclose(file_stream);


   while(TRUE)
   {

     
   }

}


But gives me a few errors:

Code:
*** Error 90 "main.c" Line 17(27,28): Attempt to create a pointer to a constant
*** Error 51 "main.c" Line 18(20,31): A numeric expression must appear here
*** Error 51 "main.c" Line 19(16,27): A numeric expression must appear here


Line 17 is fatopen.

Before I forget, my compiler version is 5.045.
skelzer



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Posts: 20
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PostPosted: Wed Apr 27, 2016 2:08 am     Reply with quote

Fixed:


Added the line

Code:
#device PASS_STRINGS=IN_RAM


after the #include <33EP512GP504.h>

and changed the declaration of
Code:
      FILE file_stream;


to
Code:
      FILE *file_stream;
Ttelmah



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PostPosted: Wed Apr 27, 2016 2:15 am     Reply with quote

#device PASS_STRINGS=IN_RAM

Needs to be added.
Then all the references to file_stream, need & (except in the declaration).
Ttelmah



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PostPosted: Wed Apr 27, 2016 2:31 am     Reply with quote

Whoa.

Your way of 'fixing' it, means you can be writing to an undeclared area of memory. It'll compile, but won't necessarily work.....

Problem is that:

File *file_stream;

Means that 'file_stream' is now a pointer, but doesn't actually declare any where for it to point 'to'.....

Declaring 'FILE file_stream;' declares the actual variable.

If you want to save typing '&', do this:

Code:

FILE actual_stream;
FILE *file_stream=&actual_stream;

Then you can use 'file_stream' as a pointer to 'actual_stream', and it will be pointing to legitimate memory....
skelzer



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PostPosted: Wed Apr 27, 2016 2:34 am     Reply with quote

Ttelmah wrote:
Whoa.

Your way of 'fixing' it, means you can be writing to an undeclared area of memory. It'll compile, but won't necessarily work.....

Problem is that:

File *file_stream;

Means that 'file_stream' is now a pointer, but doesn't actually declare any where for it to point 'to'.....

Declaring 'FILE file_stream;' declares the actual variable.

If you want to save typing '&', do this:

Code:

FILE actual_stream;
FILE *file_stream=&actual_stream;

Then you can use 'file_stream' as a pointer to 'actual_stream', and it will be pointing to legitimate memory....


It's 9 AM in the morning, I've had way too little coffee and I'm absolutely blaming it on that.

Thanks Ttelmah, you're being a real life-saver.
Ttelmah



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PostPosted: Wed Apr 27, 2016 3:06 am     Reply with quote

I'm sorry I left the '&' off when typing my stuff. Smile

We all do it.
skelzer



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PostPosted: Fri May 06, 2016 2:43 am     Reply with quote

Hello again Smile, things got really busy and I couldn't work on this project, but I'm back on it :D.

It seems the program keeps looping at
Code:
fat_init();


If I comment this line here:

Code:
#use FIXED_IO( B_outputs=PIN_B2, PIN_B10, PIN_B11, PIN_B15)


It won't get stuck on that part, but will keep returning -1 (Error I guess).



Any idea why could this be? (I'll be uploading the signals I got with my logic analyzer in a few minutes)


Last edited by skelzer on Fri May 06, 2016 3:59 am; edited 1 time in total
Ttelmah



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PostPosted: Fri May 06, 2016 3:51 am     Reply with quote

Have you actually tested that you have the sector read and write working on the device?.

Fat_init, calls the mmcsd_init. This does the speed changes to switch the device up to the faster SPI clock. The way it is written, is fractionally silly. Instead of exiting if mmcsd_init errors, it ploughs on and tries to read, to get the sector size, and data layout. So if the init has failed, it can get into a really problematical state.
I'd be checking that you have the mmcsd driver working properly before trying to get fat working.
skelzer



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PostPosted: Fri May 06, 2016 4:01 am     Reply with quote

Ttelmah wrote:
Have you actually tested that you have the sector read and write working on the device?.

Fat_init, calls the mmcsd_init. This does the speed changes to switch the device up to the faster SPI clock. The way it is written, is fractionally silly. Instead of exiting if mmcsd_init errors, it ploughs on and tries to read, to get the sector size, and data layout. So if the init has failed, it can get into a really problematical state.
I'd be checking that you have the mmcsd driver working properly before trying to get fat working.



I'd swear you comment everytime I'm editing my post... Wink

Will check it out as soon as I'm done uploading the signals I got with the logic analyzer.
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