Problem with code for reading from MMC card using PIC18F8720

[conkhicon]

I can't read out from MMC card when use PIC18F8720
- I do init it OK
- I write into OK (belong to status it's return)
- I read at address 512
MMC return to me a 0 (R1 OK)
but I loop send 0xff to wating a begin of datatoken 0xfebut don't match.
Can you help me?

#define BLOCK_LEN 16
my call:
readBlockMMC(0,512,bufMMC);
my sourcecode:
unsigned char readBlockMMC(unsigned long int DWAddr,unsigned char *pdes)
{
unsigned char localRD;
unsigned char dataToken;

Nop();
lowerSS(); // Card Active
writeCMD(17,DWAddr,0xff);// READ COMMAND (None CRC)
if(MCCResponse()!=0) {
MMC_Err = 0x30;
return(1);
}
Nop();
while(1) {// Waiting DATA TOKEN
WriteSPI(0xff);
dataToken = ReadSPI();
if(dataToken==0xfe) break;// Success
if((dataToken&0xe0)==0) {// Error Token
Nop();
MMC_Err = 0x31;
return(1);
}
}
Nop();
for(localRD=0;localRD<BLOCK_LEN;localRD++) {
WriteSPI(0xff);
*pdes = ReadSPI();
pdes++;
}
WriteSPI(0xff); // CRC
WriteSPI(0xff);
raiseSS(); // Card InActive
Nop();
return(0);
}

 

[philm]

Re: MMC help?

Try sending &HFF just before you lower ss.
If it helps, here is my AVR ASM code.

[read_sec]
'***************************************************************
'issue Read Sector command to card
'***************************************************************
'Sub Read_sec(lbasector As Long , Byval Sec2xfer As Byte)
'lbasector= Y+2,Y+3 Sec2xfer=Y+0,Y+1
'entry point if registers need to be loaded by soft stack
Read_sec:
ldd Xl, Y+0
ldd Xh, Y+1                                                 'X register pair points to Sec2xfer
ld r24, X                                                   'r24 contains Sec2xfer
ldd Xl, Y+2
ldd Xh, Y+3                                                 'X register pair points to lbasector
ld r16, X+                                                  'r16 contains bits 0 - 7 of LBA & post incr
ld r17, X+                                                  'r17 contains bits 8 - 15 of LBA & post incr
ld r18, X+                                                  'r18 contains bits 16 - 23 of LBA & post incr
ld r19, X                                                   'r19 contains bits 24 to 31 of LBA only 27 is used
'entry point if registers pre loaded
'r24 = sectors to transfer, r16 to r19 = lbasector
[Readsec]
$EXTERNAL Lba2add , Txrxspi , Txrxspi_wait4resp , Chk4error
Readsec:
rcall Txrxspi255                                            'send 255 without chip select to flush card buffer
Cbi Spiport , Sdmmccs                                   'make SD / MMC Chip Select active
rcall Lba2add                                               'convert LBA to address
ldi r23, Read_multiple_block
rcall Txrxspi
mov r23, r19                                                'send address hi
rcall Txrxspi
mov r23, r18
rcall Txrxspi
mov r23, r17
rcall Txrxspi
mov r23, r16
rcall Txrxspi_wait4resp                                     'send address lo & wait for response
rcall Chk4error                                             'check for any error
ret
[end]

[get_sec]
'***************************************************************
'Get da Sector Data from the card and Stick it in da RAM
'***************************************************************
'Sub Get_sec(buffer() , Byval Sec_expected As Byte )
'buffer()= Y+2,Y+3 Sec_expected=Y+0,Y+1
'entry point if registers need to be loaded by soft stack
Get_sec:
ldd Xl, Y+0
ldd Xh, Y+1                                                 'X register pair points to Sec_expected
ld r24, X                                                   'r24 contains Sec_expected
ldd Xl, Y+2                                                 'X register pair points to buffer
ldd Xh, Y+3
'entry point if registers pre loaded
'r24 = Sector Counter (Sec_expected)
'Xl & Xh = (X register pair) points to buffer
[Getsec]
$EXTERNAL Txrxspi_wait4token , Txrxspi , Txrxspi_wait4resp , Chk4error
Getsec:
rcall Txrxspi_wait4token                                    'wait for data token
ldi r25, 0                                                  'word counter
Getsec_loop:
cpi r25, &HFF                                               'have we got 2 bytes to go?
brne Getsec_loop1                                          'if not, keep looping
dec r24                                                     'decr sec_expected
brne Getsec_loop1                                          'have we finished?
ldi r23, Stop_transmission                                  'if so, then stop txing
rcall Txrxspi                                               'get a byte in r23
st X+, r23                                                  'store to buffer
rjmp Getsec_loop2
Getsec_loop1:
rcall Txrxspi255                                            'get a byte in r23
st X+, r23                                                  'store to buffer
Getsec_loop2:
rcall Txrxspi255
st X+, r23                                                  'again. 2 bytes = 1 word
inc r25                                                     'incr word counter
brne getsec_loop                                           'have we finished transfering 1 block
rcall Txrxspi255                                            'get crc16 hi & dump it
rcall Txrxspi255                                            'get crc16 lo & dump it
tst r24                                                     'is sector counter = 0
brne Getsec                                               'if not finished, get some more data
rcall Txrxspi_wait4resp                                     'wait for valid response
rcall Chk4error                                             'check for any error
sbi Spiport, Sdmmccs                                        'make SD / MMC Chip Select not active
ret
[end]

 

[ful babu]

Re: MMC help?

for pic to access MMC there is a very nice library in mikroC, try it ....

demo is available at **broken link removed**

regards

 

[conkhicon]

MMC question?

Have a difference between MMC which support differently command classes.

I read sandisk MMC productManual and see in CSD Rergister [95:84] field
CCC=0x5=0b 000 000 0101 support comand classes 0,2 which class 0 support Initilize MMC card and class 2 support Read Command and so on I try to write MMC card with Write Block (in class 4) failure. I can read MM Card and not Write.
do I think true?
But this card insert to mobile. It very good for read and write. Why???
Do you help me?

 

[checkmate]

Re: MMC question?

One possible reason is the address provided. Block writes can only write from the beginning of a block boundary, whilst reads can occur anywhere within the block. I havent touched MMCs for years, but I do recall this is one of the limitations.

 

[conkhicon]

Re: MMC question?

Can you help me?

#define BLOCK_LEN 16
my call:
readBlockMMC(0,512,bufMMC);
my sourcecode:
unsigned char readBlockMMC(unsigned long int DWAddr,unsigned char *pdes)
{
unsigned char localRD;
unsigned char dataToken;

Nop();
lowerSS(); // Card Active
writeCMD(17,DWAddr,0xff);// READ COMMAND (None CRC)
if(MCCResponse()!=0) {
MMC_Err = 0x30;
return(1);
}
Nop();
while(1) {// Waiting DATA TOKEN
WriteSPI(0xff);
dataToken = ReadSPI();
if(dataToken==0xfe) break;// Success
if((dataToken&0xe0)==0) {// Error Token
Nop();
MMC_Err = 0x31;
return(1);
}
}
Nop();
for(localRD=0;localRD<BLOCK_LEN;localRD++) {
WriteSPI(0xff);
*pdes = ReadSPI();
pdes++;
}
WriteSPI(0xff); // CRC
WriteSPI(0xff);
raiseSS(); // Card InActive
Nop();
return(0);
}

Do you think I'm true?

 

[conkhicon]

Re: MMC help?

I use Microchip C18 Compiler
Please post function for PIC which is runing OK.
Thanks