Need help with the MMC code

[tranjimmysd]

Hi,
I have the CCS 16F877A Proto-board. I connect it with 256 MB MMC card( brand new one, I got it from Fry's Electronic). I use SPI.
RC5 to MOSI(MMC pin2)
RC4 to MISO(MMC pin7)
RC3 to CLK (MMC pin 5)
RC1 to CS (MMC pin1)

the MMC is powered by 3.3 volt. The PIC is powered by 5.0 volt. Since the voltage level for RC1, RC4 and RC3 is 5.0 volt. So I use voltage divider 3.3 K and 1.8 K Ohm in MOSI, CS, CLK to make sure that those MMC pins will have 3.3 volt level.

I use this code from the internet to test it. Based on the debug output to rs232, i can tell that I got some responses from MMC when I write to it. But when it comes to the read function. I get nothing when trying to read back the test pattern ( a bunch of number 7). Here is the code. Can anyone tell me if I am missing anything:

*******************************************
#include <16f877a.h>
#device ICD=TRUE
#fuses HS, NOPROTECT, PUT, NOWDT, BROWNOUT, NOLVP, NOCPD
#use delay(clock=20000000)
#use rs232 (baud=9600, xmit=PIN_C6,rcv=PIN_C7)
#include <stdlib.h>
#include <input.c>

#define LOW(var) (var & 0xFF)
#define HIGH(var) (var>>8)

int mmc_init();
int mmc_response(unsigned char response);
int mmc_read_block(unsigned long block_number);
int mmc_write_block(unsigned long block_number);
int mmc_get_status();


/************************** MMC Init **************************************/
/* Initialises the MMC into SPI mode and sets block size, returns 0 on success */

int mmc_init()
{
int i;

SETUP_SPI(SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_4 | SPI_SS_DISABLED);

*0x94 |= 0x40; // set CKE = 1 - clock idle low
*0x14 &= 0xEF; // set CKP = 0 - data valid on rising edge

OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)

for(i=0;i<10;i++) // initialise the MMC card into SPI mode by sending clks on
{
SPI_WRITE(0xFF);
}

OUTPUT_LOW(PIN_C2); // set SS = 0 (on) tells card to go to spi mode when it receives reset

SPI_WRITE(0x40); // send reset command
SPI_WRITE(0x00); // all the arguments are 0x00 for the reset command
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x95); // precalculated checksum as we are still in MMC mode

printf("Sent go to SPI\n\r");

if(mmc_response(0x01)==1) return 1; // if = 1 then there was a timeout waiting for 0x01 from the mmc

printf("Got response from MMC\n\r");

i = 0;

while((i < 255) && (mmc_response(0x00)==1)) // must keep sending command if response
{
SPI_WRITE(0x41); // send mmc command one to bring out of idle state
SPI_WRITE(0x00); // all the arguments are 0x00 for command one
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
i++;
}
if(i >= 254) return 1; // if >= 254 then there was a timeout waiting for 0x00 from the mmc

printf("Got out of idle response from MMC\n\r");

OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)

SPI_WRITE(0xFF); // extra clocks to allow mmc to finish off what it is doing

OUTPUT_LOW(PIN_C2); // set SS = 0 (on)

SPI_WRITE(0x50); // send mmc command one to bring out of idle state
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x02); // high block length bits - 512 bytes
SPI_WRITE(0x00); // low block length bits
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF

if((mmc_response(0x00))==1) return 1;
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
printf("Got set block length response from MMC\n\r");
return 0;
}

/************************** MMC Get Status **************************************/
/* Get the status register of the MMC, for debugging purposes */

int mmc_get_status()
{

OUTPUT_LOW(PIN_C2); // set SS = 0 (on)

SPI_WRITE(0x58); // send mmc command one to bring out of idle state
SPI_WRITE(0x00);
SPI_WRITE(0x00);
SPI_WRITE(0x00); //
SPI_WRITE(0x00); // always zero as mulitples of 512
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
return 0;
}

/************************** MMC Write Block **************************************/
int mmc_write_block(unsigned long block_number)
{
unsigned long i;
unsigned long varh,varl;

varl=((block_number&0x003F)<<9);
varh=((block_number&0xFFC0)>>7);

printf("Write block\n\r"); // block size has been set in mmc_init()

OUTPUT_LOW(PIN_C2); // set SS = 0 (on)

SPI_WRITE(0x58); // send mmc write block
SPI_WRITE(HIGH(varh));
SPI_WRITE(LOW(varh));
SPI_WRITE(HIGH(varl));
SPI_WRITE(0x00); // always zero as mulitples of 512
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF

if((mmc_response(0x00))==1) return 1;
printf("Got response to write block\n\r");

SPI_WRITE(0xFE); // send data token

for(i=0;i<512;i++)
{

SPI_WRITE(7 + '0'); // send data

}

SPI_WRITE(0xFF); // dummy CRC
SPI_WRITE(0xFF);

if((SPI_READ(0xFF)&0x0F)!=0x05) return 1;

printf("Got data response to write block\n\r");

OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
return 0;
}



/************************** MMC Read Block **************************************/
/**** Reads a 512 Byte block from the MMC and outputs each byte to RS232 ****/
int mmc_read_block(unsigned long block_number)
{
unsigned long i;
unsigned long varh,varl;

varl=((block_number&0x003F)<<9);
varh=((block_number&0xFFC0)>>7);

OUTPUT_LOW(PIN_C2); // set SS = 0 (on)

SPI_WRITE(0x51); // send mmc read single block command
SPI_WRITE(HIGH(varh)); // arguments are address
SPI_WRITE(LOW(varh));
SPI_WRITE(HIGH(varl));
SPI_WRITE(0x00);
SPI_WRITE(0xFF); // checksum is no longer required but we always send 0xFF
if((mmc_response(0x00))==1) return 1; // if mmc_response returns 1 then we failed to get a 0x00 response (affirmative)

printf("Got response to read block command\n\r");

if((mmc_response(0xFE))==1) return 1; // wait for data token

printf("Got data token\n\r");

for(i=0;i<512;i++)
{
putc(SPI_READ(0xFF)); // we should now receive 512 bytes
}

SPI_READ(0xFF); // CRC bytes that are not needed
SPI_READ(0xFF);

OUTPUT_HIGH(PIN_C2); // set SS = 1 (off)
SPI_WRITE(0xFF); // give mmc the clocks it needs to finish off

printf("\n\rEnd of read block\n\r");

return 0;
}

/************************** MMC get response **************************************/
/**** Repeatedly reads the MMC until we get the response we want or timeout ****/

int mmc_response(unsigned char response)
{
unsigned long count = 0xFFFF; // 16bit repeat, it may be possible to shrink this to 8 bit but there is not much point

while(SPI_READ(0xFF) != response && --count > 0);

if(count==0) return 1; // loop was exited due to timeout
else return 0; // loop was exited before timeout
}



void main(void)
{
printf("testing for MMC");
mmc_init();
mmc_write_block(0);

if (mmc_read_block(0) == 1)
{
printf("MMC not response for reading \r\n");
}

while(1)
{

}
}

[icefield]

[newguy]

See this thread:

http://www.ccsinfo.com/forum/viewtopic.php?t=22777

The last post has a link to a philips semiconductor application note on level shifting. It may be of help.

[tranjimmysd]

Many thanks Icefield and Newguy. Good suggestions. I will give it a try and let you guys know how it goes.

[PCM programmer]

There are some serious problems with your level translation,
and with the MMC specification's requirement for pull-ups, etc.

But before considering that, the code that you posted uses
Pin C2 for the CS (or slave select). But in your pin list,
you're using pin C1.

You must either change your hardware to use Pin C2,
or you must modify the driver so it uses pin C1.

[tranjimmysd]

Hi,
Sorry for the typo. I did use C2 for the chip select.

I put this circuit( the first part) in between MISO and RC4 to make sure that the RC4/SDI pin on the pic will receive proper 5 volt level.

http://www.circuitcellar.com/pastissues/articles/Tom99/figure1.htm

with that circuit, I can go little further in the read function until where the function asks for the data token(if((mmc_response(0xFE))==1) return 1; // wait for data token). Asking for 0xFE, the MMC returns 0xFF.

I stuck. Any suggestion will be appreciated.

Jim

[PCM programmer]

What is your version of the compiler ?

[tranjimmysd]

Hi,
The compiler version 3.224

PCWH compiler
IDE version 3.224
PCB Version 3.224
PCM version 3.224
PCH version 3.224

Thanks

[PCM programmer]

His SPI setup has got some problems. I can see at least two problems.
I don't have time to finish writing it all up tonight. I'll do it tomorrow
morning and then post it.


Also, I'm curious as the manufacturer and part number of your MMC card.
I'd like to download the data sheet for it.

[tranjimmysd]

Hi,
The MMC card made by Power Quotient International Co., Ltd
www.pqi.com.tw

It called Reduced Size MMC

Thank you very much for all your helps

Jim

[PCM programmer]

Actually, I thought I had found two bugs, but I've only found one so far.

This line of code has a bug.

[tranjimmysd]

Hi,
I tried that but it did not work. :-(
I made my circuit based on this
http://www.captain.at/electronics/pic-mmc/
I aslo added in the volt level shifter in between the MMC output pin to the PIC SPI input .

I made my volt level shifter by using some of the resistors and transitors( I got them from Radioshack, the NPN high speed switching transistors).


Jim

[PCM programmer]

CCS has a driver. It's called MMC_SPI.C, and it's in this folder:
c:\Program Files\Picc\Drivers

Have you tried that one ?

[tranjimmysd]

Hi,
I tried the CCS driver, but it did not work too.

Have anyone in this forum ever tried this MMC code? http://www.microchipc.com/sourcecode/#mmc

if the code is working on for others, then there must be something wrong with my hardware connection.


Do you know any simple MMC/PIC development platform( PIC on 5 volts and MMC on 3.3 volts and support CCS ICD-U40) out there that I can purchase?

I like to test that MMC code with the surely-working-hardware.

Many thanks for all your helps
Jim

[newguy]

I could be wrong, but I was under the impression that the ICD-U40 could program the low-voltage (LF) pics. Why don't you try to get an LF pic, run/program it at 3.3V, and then you can directly connect it to the 3.3V MMC card?