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baltazar
Joined: 12 Nov 2007
Posts: 5
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| mmcsd.c + PIC24 |
 Posted: Tue Feb 01, 2011 1:51 pm |
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Hello fellows!
I'm trying to run the ex_mmcsd.c with a PIC24FJ but I always get the Could not init the MMC/SD!!!! message...
I've already checked my hardware connections and it's fine. But I have just one question about this, once the PIC's power supply is also 3v3, do I need to use the pull-up resistors?
The #use spi works with the PIC24 family?
My compiler version is 4.114
Just one more thing, I'm using a MicroSD with the SD adapter.
Here is my code:
| Code: |
/////////////////////////////////////////////////////////////////////////
//// ex_mmcsd.c ////
//// ////
//// Similar to ex_extee.c, an example that demonstrates ////
//// writing and reading to an MMC/SD card. ////
//// ////
/////////////////////////////////////////////////////////////////////////
//// (C) Copyright 2007 Custom Computer Services ////
//// This source code may only be used by licensed users of the CCS ////
//// C compiler. This source code may only be distributed to other ////
//// licensed users of the CCS C compiler. No other use, ////
//// reproduction or distribution is permitted without written ////
//// permission. Derivative programs created using this software ////
//// in object code form are not restricted in any way. ////
/////////////////////////////////////////////////////////////////////////
//These settings are for the CCS PICEEC development kit which contains
//an MMC/SD connector.
#include <24FJ128GA010.h>
#fuses NOWDT, NOPROTECT
#use delay(internal=8M)
#use rs232(baud=9600, UART2, errors)
#include <stdlib.h> // for atoi32
//meda library, a compatable media library is required for FAT.
#use fast_io(g)
#define MMCSD_PIN_SCL PIN_G6 //o
#define MMCSD_PIN_SDI PIN_G7 //i
#define MMCSD_PIN_SDO PIN_G8 //o
#define MMCSD_PIN_SELECT PIN_D12 //o
#include <mmcsd.c>
#include <input.c>
void main(void)
{
BYTE value, cmd;
int32 address;
printf("\r\n\nex_mmcsd.c\r\n\n");
if (mmcsd_init())
{
printf("Could not init the MMC/SD!!!!");
while(TRUE);
}
do {
do {
printf("\r\nRead or Write: ");
cmd=getc();
cmd=toupper(cmd);
putc(cmd);
} while ( (cmd!='R') && (cmd!='W') );
printf("\n\rLocation: ");
address = gethex();
address = (address<<8)+gethex();
if(cmd=='R')
{
mmcsd_read_byte(address, &value);
printf("\r\nValue: %X\r\n", value);
}
if(cmd=='W') {
printf("\r\nNew value: ");
value = gethex();
printf("\n\r");
mmcsd_write_byte(address, value);
mmcsd_flush_buffer();
}
} while (TRUE);
}
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baltazar
Joined: 12 Nov 2007
Posts: 5
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| Posted: Wed Feb 02, 2011 10:07 am |
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I've tried to put 10k pull-up resistors in SS, SDO and SDI pins, but it's still not working...
I'm pretty sure that there is something wrong with the mmcsd library and PIC24 family, but I can't find the problem. |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Wed Feb 02, 2011 10:21 am |
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Pull-up resistors are required by MMC and SD card specification for those card signals not driven by the processor (SDI and contacts unused in SPI mode). But they are very unlikely a reason for the protocol to fail.
Most likely, either problems with the SPI setup or specific PCD bugs, that causes failure of some internal library operation, e.g. block calculations.
Basically, I see no other option than tracing the library action with a hardware debugger (preferably MPLAB), identify the problems and change the code accordingly.
#use spi won't allow some necessary operations, e.g. SPI frequency change. I never used it with PCD. |
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baltazar
Joined: 12 Nov 2007
Posts: 5
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| Posted: Wed Feb 02, 2011 10:57 am |
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Hi FvM!
I did what you said:
| Quote: |
Basically, I see no other option than tracing the library action with a hardware debugger (preferably MPLAB), identify the problems and change the code accordingly.
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and I found something interesting...
I'm working on it by now, but seems that, for some reason, the library identifies the SD card as a MMC card and because of that many functions does not work as they should do.
To be more specific, the "identification problem" occurs in this fragment of the mmcsd.c library:
| Code: |
/* an mmc will return an 0x04 here */
if(r1 == 0x04)
g_card_type = MMC;
else
g_card_type = SD;
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If I force the library to accept the SD format as a card type, then it works! At least it seems to work until now...
Do you have any idea about this "strange behavior"?
Thanks for the help! |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Wed Feb 02, 2011 11:42 am |
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That's faster success than expectable.
There's no understandable reason, why ACMD41 is answered by a SD card with the illegal command bit.
So something must be wrong. I noticed that the mmcsd driver doesn't reduce the SPI clock during identification
phase as required by the standard. Are you possibly clocking the card too fast?
However, I have a good SD card driver from brushelectronics.com and don't need to fix the rather
limited mmcsd code.
Good luck! |
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