About MMC Card Read/Write

[conkhicon]

mmc pic read write

Dear all,
I developing PIC 18F8720 project use MMC with hardware SPI function in MCU interface, I had successfully to do reset and initialize the MMC and Read OCR, CSD Register OK, and may be read-singleBolck(CMD17) OK (Status return OK but don't know data is true),
but when i want to write-block (CMD24) to the MMC, the response-data is strange, it is 0x07 (the correct one is 0xE5). any one can help me, what mistake?? (I use KingMax and Sandisk Card).
Block Size = 512Bytes, address is boundary of 512
If I use Nokia,Seimen MMC Card and I only Write OK (belong to status return)
and read failure.

 

[dpsman]

cmd24 spi

I´ve only got strange responses from SD/MMC when I missed a certain step.
Can you describe the exact sequence you are using to issue a CMD24 and perform the write?

 

[conkhicon]

sandisk card response 0x07

#define BLOCK_LEN 512
unsigned char readBlockMMC(unsigned long int DWAddr,unsigned char *pdes)
{
extern unsigned char tmpkd[];
unsigned char localRD;
unsigned char commandResponse;
unsigned char dataToken;
unsigned int localc;

SetCSSPI();
WriteSPI(0xff); // Dummy
ClearCSSPI(); // Card Active
writeCMD(17,DWAddr,0xff); // READ COMMAND (None CRC)
commandResponse = MCCResponse();
if(commandResponse!=0) {
SetCSSPI(); // Card In-Active
WriteSPI(0xff); // Dummy
MMC_Err = 0x30;
return(1);
}
localc = 0;
while(1) { // Waiting DATA TOKEN or ERROR TOKEN
dataToken = ReadSPI();
if(dataToken==0xfe) break; // Success
localc++;
if((dataToken&0xe0)==0) { // Error Token
if(dataToken!=0) {
MMC_Err = 0x31;
return(1);
}
}
}
Nop();
for(localRD=0;localRD<BLOCK_LEN;localRD++) {
*pdes = ReadSPI();
tmpkd[localRD] = *pdes;
pdes++;
}
ReadSPI(); // CRC
ReadSPI();
SetCSSPI(); // Card In-Active
WriteSPI(0xff); // Dummy
return(0);
}

 

[techie]

writespi

There is a very good application given in circuit cellar #176. Maybe you can check and see that to compare if you are doing anything wrong.

 

[dpsman]

If I didn't misunderstand your code, you are wating for data tokens...
But, when you issue a CMD24 you have to send data tokens,

Here is piece of working code:

mmc_CS_on;

r_value = mmc_cmd(CMD24,address,0); //internally waits for response R1
mmc_putchar(0xFF);
mmc_putchar(0xFE); //sends DATA token

for(i = 0; i < 512; ++i)
mmc_putchar(buffer); // sends 512B data

mmc_putchar(0x00); // sends DUMMY 16bits CRC
mmc_putchar(0x00);

while(mmc_read_r1()==0xFF);
if((U0RXBUF & 0x1F) != 0x05)error_data_write_count++;
while(mmc_read_r1()==0x00);// waits for WRITE to end..

mmc_CS_off;

 

[conkhicon]

I fix my problem
Any one use hardware Pheripral SPI in PIC interface MMC Card attend:

when you read SPI() for waiting a response, clock is shift out, data is shift in PIC
but the same time, data in SSPBUF shift out into MMC is ramdom, because this MMC Card refuse.
Replace code:
response = ReadSPI();
With:
WriteSPI(0xff);
response = SSPBUF;

 

[acceph]

i have similar problem with MMC Card also,
i make a data logger, previously i used SD Card for storage, then after do many test and success, i want it able to use MMC card too, so i change the SDCard with MMC Card. but when using MMC Card the system is hang during Write file.. i don't know the reason..
during initialisation both of card give ready status, so i think it's okay in initialisation.. please show me my mistake..