Giao tiếp card MMC ?

[mynhanxst]

#include <16f877a.h>
#DEVICE *=16 CCSICD=TRUE
/// add new open file handling
//// working May 13 2003 with 18F452
//// write append tested for no new cluster append
#fuses HS,NOWDT,NOPROTECT,NOPUT,NOLVP,NOBROWNOUT,NOWRT


#use delay(clock=20 000 000)
#use rs232(baud=9600, bits=8, parity = N, xmit=PIN_C6, rcv=PIN_C7)
#use rs232(DEBUGGER)
#USE FAST_IO(A)
#USE FAST_IO(B)
#USE FAST_IO(C)
#USE FAST_IO(D)
#USE FAST_IO(E)
////////////////
/// test of SPI interface at 40 mz prior to merging into web server
///
/// hardware SDI is C4 SDO is C5 SCK is C3
#DEFINE _CS PIN_C2
#define PIC_MODE PIN_A0 /// NIC or DRAM
#DEFINE MAX_FILES 2 /// max number of open files
#DEFINE MMC_BUFF_SIZE 32 /// 32 for PCM





///////////////////////////// SPI interface for ///////////
// Multi Media Card FAT16 only
// FAT16 is a copyright of Microsoft
// This program was developed for personal use only based on
// information Microsoft placed in the public domain
// The code will read MMC SD cards in SPI mode previously formatted
// on a PC
// To write a file update to cards a 512 byte buffer is required
// to store the existing info from a sector prior to updating
// An append or writing a new sector can be done without the buffer
// THe PIC is at 5v and the MMC at 3.3v ... a 5v 7407 open collector
// buffer is used to level convert with 2.2k pull ups on the SPI lines
// the 3.3v MMC supply is either obtained from the 5v via a 3.3 Vreg
// or is dropped down via a led ( also works as a power on indicator)
// and smoothed via 100 uf cap
//
// the MMC card and the PIC aren't ever in sync so the card has to be polled to
// get the required response. Often a command is just repeated until the CARD responds
// and the card is polled until it sends the data
///////////////////////////////////////////////////////////
//
/// PIN Assignments //////////////////////////////
/// _CS PIN_C2 // chip select for MMC
/// SDO PIN_C5
/// CLK PIN_C3
/// SDI PIN_C4
// SPI hardware pins are
// SDO C5
// SDI C4
// SCK C3
///////////////////////////////////////////////////////////////

///// Note old values needed before all SPI modes could be set up using SPI_setup
/// for 16 parts ///////////
//#DEFINE SSPCON 0x14
//#DEFINE SSPSTAT 0x94
//#BIT SMP=SSPSTAT.7
//#BIT CKE=SSPSTAT.6
//#BIT CKP=SSPCON.4
//#BIT SSPEN=SSPCON.5
//////////////////////////////

// For 18F452
//#DEFINE SSPSTAT 0x0FC7
//#DEFINE SSPCON1 0x0FC6
//#BIT SMP=SSPSTAT.7
//#BIT CKE=SSPSTAT.6
//#BIT CKP=SSPCON1.4

//#DEFINE MAX_FILES 2 /// max number of open files
//#DEFINE MMC_BUFF_SIZE 32 /// 32 for PCM
#DEFINE MMC_FILE_NAME_SIZE 32

#DEFINE ROOT_CLUSTER 0
#DEFINE NEXT_CLUSTER 1

#define MMC_INIT_TRACE FALSE
#define MMC_CMD_TRACE FALSE
#define MMC_CLUSTER_TRACE FALSE // if true prints to serial port
#define MMC_OPEN_TRACE FALSE // if true prints to serial port
#define MMC_READ_TRACE FALSE // if true prints file_addr,cluster index etc
#define MMC_WRITE_TRACE FALSE
#define MMC_READ_BLOCK_TRACE FALSE
#define MMC_SET_BLOCK_LEN_TRACE FALSE
#define MMC_WRITE_BLOCK_TRACE FALSE
#define MMC_NEW_CLUSTER FALSE
////// MMC prototypes
#separate
int init_MMC(int max_tries);
#separate
int open_file(int fnbr,char *fname,int16 rec_length);
#separate
int file_read(int8 fnbr,char *buff);
#separate
int file_write(int8 fnbr,int *buff);
#separate
int file_set(int fnbr,int32 offset);
#separate
int file_new_cluster(int8 fnbr,int8 mode); /// mode 1=fat1 2=fat2

int32 atoint32 (char *s );
signed int strncmp(char *s1, char *s2, int n);
///////////////////// MMC GLOBALS /////////////////////////////
int16 cluster_size_bytes; // bytes in a cluster
//int16 dir_cluster_chain_ptr; // link to the first cluster in the dir

int32 fat1_address; // physical address of fat1 cluster table assigned by INIT_MMC
int32 fat2_address; // physical address of fat2 cluster table assigned by INIT_MMC
int32 root_dir_address; // physical address of volume,file,folder tiles assigned by INIT_MMC
int32 data_area_address; // physical address of data area assigned by INIT_MMC
int32 winhex_adj; // Win hex hides the bytes in the reserved sectors
// this means Fat1 is address 512
// so adj is fat1-512

int32 block_size; // current MMC block size

int MMC_init=FALSE;

int MMC_dir_protected=TRUE;

////////// open file specific globals ///////////////////////
struct
{
char name[MMC_FILE_NAME_SIZE+1]; // fopen file name
int32 dir_addr_ptr; // physical address of this files tile info
int16 root_cluster_ptr; // location of first cluster in FAT
int16 this_cluster_ptr; // location of current cluster in FAT
int16 next_cluster_ptr; // location of the next cluster for a file or sub dir in FAT
int32 addr_ptr; // physical address in the file the current
// cluster points to
// address=(this_chain_ptr-2)*cluster_size_bytes+data_area_address
//
// cluster_addr(THIS_CLUSTER) assigns it
// cluster_addr(NEXT_CLUSTER) moves to the data the next
// cluster points to
int32 size; // size of open file in bytes
int32 cluster_offset; // offset within the file representing the start of the current cluster
// (0 is start and ends with the cluster contianing eof )
// auto increased by cluster_size_bytes each time a new cluster is entered

int32 offset; // current offset into the open file ( 0 is start size(file size) is end)
// auto increased by rec size each time a rec is read
// addr_prt+offset-cluster_offset is physical address of
// the current position within the file
// the physical positions are not always contiguous since the
// clusters of the file are not always adjacent to each other
int16 rec_size; // fopen record_size
// char buff[MMC_BUFF_SIZE+1]; // used for open and for read write
// init MMC uses file 0 buff to fetch the globals

} file[MAX_FILES];
#separate
int mmc_cmd(int8 cmd,int32 address,int8 tries,int8 valid,int8 invalid)
{
int i,r1;
for( i=0;i<16;i++) SPI_READ(0xFF);// digest prior operation
// commands
// 7 6 5 4 3 2 1 0
// 0 1 b b b b b b bbbbbb=cmd
// 16=0x50 set blocklength
// 17=0x51 read block
// 24=0x58 write block
#if MMC_CMD_TRACE
printf("\n\r cmd=%2X \n\r",cmd);
#endif
SPI_READ(cmd);
SPI_READ(MAKE8(address,3));
SPI_READ(MAKE8(address,2));
SPI_READ(MAKE8(address,1));
SPI_READ(MAKE8(address,0));
SPI_READ(0x95);
// card comes up in MMC mode and requires a valid MMC cmd to switch to SPI mode
// valid crc for MMC 0x40 cmd only
// spi mode doesn't require the CRC to be correct just there

for(i=0;i< tries;i++) {
r1=SPI_READ(0xFF);
#if MMC_CMD_TRACE
printf(" %2X",r1);
#endif
if (r1==valid) break;
if (r1==invalid) break;
}
return(r1);
}


#separate
int set_BLOCKLEN( int32 size)
{
int r1;

r1=mmc_cmd(0x50,size,16,0x00,0x40); /// cmd.data,tries,valid code,invalid code
if (r1==0x00) goto done ;
if (r1==0x40) goto invalid;


return(false);
invalid:
#IF MMC_SET_BLOCK_LEN_TRACE
printf("\n\r para err\n\r");
#ENDIF
return(false);
done:
block_size=size; //// assign global block size
//printf("\n\r blk size=%lu",block_size);
return(true);

}
#separate
int read_BLOCK( int32 address, char *buff)
{
//// low level read ..requires block len to be called first to set global blocksize
int r1;
long i,iw; /// allows large gt 255 buff size addressing
//int data[128];
r1=mmc_cmd(0x51,address,16,0x00,0x40);

if (r1==0x00) goto get_token ; // we can read data payload
if (r1==0x40) goto invalid;

#IF MMC_READ_BLOCK_TRACE
printf("\n\r read block err 1 address=%lu \n\r",address);
#ENDIF
return(false);
invalid:
#IF MMC_READ_BLOCK_TRACE
printf("\n\r read block err 2 adress=%lu \n\r",address);
#ENDIF
return(false);
get_token:
for(iw=0;iw<1024;iw++){
r1=SPI_READ(0xFF);
//data[iw]=r1;
if (r1==0xFE) goto read_data; // read token $FE
}
#IF MMC_READ_BLOCK_TRACE
printf("\n\r read block err 3 address=%lu \n\r",address);
#ENDIF
return(false);
read_data:
#IF MMC_READ_BLOCK_TRACE
printf("\n\r read block tries for FE =%lu \n\r",iw);
#ENDIF

for (i=0;i<block_size;i++) buff[i]=SPI_READ(0xFF);
SPI_READ(0xFF); // read crc
SPI_READ(0xFF);

return(true);
}

//////////////////////////////////////////////////////////////////
///////////////////////////////// INIT MMC ///////////////////////
//////////////////////////////////////////////////////////////////
#separate

int init_MMC(int max_tries)
{
int32 start_lsec=0;
int16 sec_resv,sec_for_FAT,bytes_per_sector,root_dir_ent ries,
sec_for_data,count_of_clusters,root_dir_sectors,to tal_sectors;
int i,tries,sec_per_cluster,c;
char buff[32];
tries=0;
cmd0:
///////////////////// place null treminators in globals fname and buff
for(i=0;i<MAX_FILES;i++)
{
file[i].name[0]=0;
file[i].rec_size=32; //// default rec_size = 32 byte tile size of FAT16
}
//buff[MMC_BUFF_SIZE]=0;
//frec_size=32; //// default rec_size = 32 byte tile size of FAT16
output_high(_CS); /// reset chip hardware !!! required
delay_ms(20);
for(i=0;i<20;i++) SPI_READ(0xFF); // min 80 clocks to get MMC ready
output_low(_CS); /// !!! required
delay_ms(20);
#if MMC_INIT_TRACE
printf("cmd0");
#ENDIF
c=mmc_cmd(0x40,0x00000000,128,0x01,0x99);

if (c==0x01) goto exit_cmd1;

// note: i must cycle at least 8 times (16 is safe )

if (tries++<max_tries) goto cmd0; /// restart
else
return (10);
exit_cmd1:
// CPDMOD - This SOMETIMES seems to be necessary
// output_high(_CS);
// SPI_READ(0xFF); // min 8 clocks to get MMC ready
// output_low(_CS);
//CPDMOD End


tries=0;
cmd1:

/// now try to switch to idle mode
/// Note: cmd1(idle) is the only command allowed after a cmd0(reset)
//

c=mmc_cmd(0x41,0x00000000,128,0x00,0x99);
if (c==0x00) { goto ready;}


if( tries++<max_tries) { printf("cmd1"); goto cmd1;}
else return(11);
ready:
//for( i=0;i<32;i++) SPI_READ(0xFF);// digest operation
/// MMC is inialized and in idle state ready for commands
////
//// we need to first access the master boot sector physical address=0
///
if(set_BLOCKLEN((int32)32)==false) return(12); /// sets global block_size to 32

if (read_block(0x00000000,buff)==false) return (99); /// read the first few bytes
#if MMC_INIT_TRACE
printf("\n\r sector0=");
for(i=0;i<32;i++)printf("%2X ",buff[i]);
#ENDIF
if (buff[0]==0xEB || buff[0]==0xE9)
{
/// sector 0 is the boot sector
#if MMC_INIT_TRACE
printf("\n\r boot sector= 0");
#ENDIF
}
else
{
//// partition

/// access the master boot sector physical address 0 at offset 1BE
if (read_BLOCK(0x000001BE,buff)==false) return(13);
#if MMC_INIT_TRACE
for(i=0;i<32;i++)printf("%2X ",buff[i]);
#ENDIF
// start_lsec is address of the partion boot sector
start_lsec=make32(buff[11],buff[10],buff[9],buff[8]);
#if MMC_INIT_TRACE
printf("\n\r boot sector= %lu",start_lsec);
#ENDIF
if (read_BLOCK(start_lsec*512,buff)==false) return(14);
}

bytes_per_sector=make16(buff[12],buff[11]);
if(bytes_per_sector!=512) return(15);
sec_per_cluster=buff[13];
cluster_size_bytes=(int16)sec_per_cluster*bytes_pe r_sector;


sec_resv=make16(buff[15],buff[14]);

root_dir_entries=make16(buff[18],buff[17]);// number of 32 byte tiles

total_sectors=make16(buff[20],buff[19]);

sec_for_FAT=make16(buff[23],buff[22]);
//branch to file directory
fat1_address=(start_lsec+sec_resv)*bytes_per_secto r;
fat2_address=fat1_address+bytes_per_sector*sec_for _FAT;
root_dir_address=(sec_for_FAT*2+start_lsec+sec_res v)*bytes_per_sector;
data_area_address=root_dir_address+root_dir_entrie s*32;
///// check for FAT16
root_dir_sectors=root_dir_entries>>4;

sec_for_data=total_sectors - sec_resv -sec_for_fat*2 -root_dir_sectors;

count_of_clusters=sec_for_data/sec_per_cluster;

if (count_of_clusters <4085 || count_of_clusters>65525) return(17);

winhex_adj=fat1_address-bytes_per_sector;
return(0);
}
#separate
int get_CID(char s)
{int i,r1;
r1=mmc_cmd(0x4A,0x00000000,16,0x00,0x99);


if (r1==0x00) goto get_token ; // we can read data payload

return(false);
get_token:
for(i=0;i<16;i++)if (SPI_READ(0xFF)==0xFE) goto read_CID; // read token $FE
return(false);
read_CID:
for (i=0;i<18;i++)
s[i]=SPI_READ(0xFF);

return(true);
}
#separate
int get_CSD(char s)
{int i,r1;
r1=mmc_cmd(0x49,0x00000000,16,0x00,0x99);


if (r1==0x00) goto get_token ; // we can read data payload

return(false);
get_token:
for(i=0;i<16;i++)if (SPI_READ(0xFF)==0xFE) goto read_CSD; // read token $FE
return(false);
read_CSD:
for (i=0;i<18;i++)
s[i]=SPI_READ(0xFF);

return(true);
}


#separate
int write_BLOCK( int32 address,char *buff,int16 size)
{
/// low level write ....MMC restriction is that exactly 512 bytes must be written
/// so a 512 byte section is read in starting at address the first (size) bytes
/// are over written with the new data and the updated 512 bytes written back
/// the starting address of the block that contains the requeseted address
///
/// the data may span a block if so it is split and two writes are done
/// so as to maitain MMC 512 write boundary restrictions

int r1,a,b,c,d;
int16 i,blk_offset,bytes_posted;
char tmp_buff[512];
int32 block_address;

#if MMC_WRITE_BLOCK_TRACE
printf("addr=%lu",address);
#endif

a=make8(address,3);
b=make8(address,2);
c=make8(address,1);
c=c & 0b11111110;
d=0;
block_address=make32(a,b,c,d); //// address int divided by 512
#if MMC_WRITE_BLOCK_TRACE
printf("wb>> size=%lu payload=",size);
for(i=0;i<size;i++)printf("%c",buff[i]);
#endif

// first set up the block size to 512
if(set_BLOCKLEN((int32)512)==false) return(false); // sets global block_size

if(block_size!=512) return(false);
bytes_posted=0; /// no data updated yet

////////////////////////////////////////////////
next_block: /// loop back here for second block
////////////////////////////////////////////////
#if MMC_WRITE_BLOCK_TRACE
printf("\n\r blk addr=%lu \n\r",block_address);
#endif

if((block_address < data_area_address) && MMC_dir_protected) return(false);

MMC_dir_protected=true;
#if MMC_WRITE_BLOCK_TRACE
printf("read blk");
#endif
/// first read in the existing block
if(read_block(block_address,tmp_buff)==false)
{return(false) ;

}

/// now update the block with new data
blk_offset=(address - block_address); /// offset within the block
#if MMC_WRITE_BLOCK_TRACE
printf("blk_offset=%lu size=%lu",blk_offset,size);
#endif

if( blk_offset + size > 512 )
{
// data spans the block so write to end of block first

#if MMC_WRITE_BLOCK_TRACE
//// original data
printf("\n\r spans wb=");
for(i=blk_offset;i<512;i++)printf("%c",tmp_buff[i]);
#endif

for (i=blk_offset;i < 512;i++)tmp_buff[i]=buff[i-blk_offset];

#if MMC_WRITE_BLOCK_TRACE
/// updated data
printf("\n\r spans wb*=");
for(i=blk_offset;i<512;i++)printf("%c",tmp_buff[i]);
#endif

bytes_posted=512-blk_offset; /// wrote from offset to end of block

#if MMC_WRITE_BLOCK_TRACE
printf("\n\r posted=%lu",bytes_posted);
#endif

}
else
{
//original or remaining spanned block data fits in next block or original block

#if MMC_WRITE_BLOCK_TRACE
printf(" blk offset=%lu",blk_offset);
/// original data
printf("\n\r wb=");
for(i=blk_offset;i<blk_offset+size;i++)printf("%c" ,tmp_buff[i]);
#endif

for (i=blk_offset;i<blk_offset+ size;i++)tmp_buff[i]=buff[bytes_posted+i-blk_offset];

#if MMC_WRITE_BLOCK_TRACE
/// updated data
printf("\n\r wb*=");
for(i=blk_offset;i<blk_offset+size;i++)printf("%c" ,tmp_buff[i]);
#endif

bytes_posted=size;

#if MMC_WRITE_BLOCK_TRACE
printf("\n\r posted=%lu",bytes_posted);
#endif

}

///////////////////////////////////
/////////// write out the block
//////////////////////////////////
#if MMC_WRITE_BLOCK_TRACE
printf("wb>> writing block %lu",block_address);
#endif
r1=mmc_cmd(0x58,block_address,16,0x00,0x40);


if (r1==0x00) goto send_token ; // we can send data payload
if (r1==0x40) goto invalid;


return(false);
invalid:
printf("\n\r write block err %2X\n\r",r1);
return(false);
send_token:
SPI_READ(0xFE);

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

SPI_READ(tmp_buff[i]); /// send payload
}


SPI_READ(0xFF); // send dummy chcksum
SPI_READ(0xFF);
r1=SPI_READ(0xFF);
for( i=0;i<0x0fff;i++) {
r1=SPI_READ(0xFF);// digest prior operation
if (r1!=0x00) break;
}

if(size > bytes_posted)
{
/// data spanned block so we need to upadte next block as well
size=size-bytes_posted;
block_address=block_address+512;/// advance a block

address=address+bytes_posted; /// move address ptr forward

goto next_block;
}


return(true);
}

#separate
void dump_block()
{
int in_buff[12],c,i,j;
int32 read_address;
char buff[MMC_BUFF_SIZE+1];
for(i=0;i<12;i++)in_buff[i]=0;
printf("\n\r Input Start address:");
j=0;
do {
c=getc();
in_buff[j++]=c;
putc(c);
}while(c!=13);
in_buff[j-1]=0;

read_address=atoint32(in_buff);
if (read_BLOCK(read_address,buff)==true){
printf(" BLOCK\n\r");
for(j=0;j<MMC_BUFF_SIZE;j=j+8)
{
printf("%4LX ",read_address+j);
for(i=0;i<8;i++)printf(" %2X",buff[i+j]);
printf("\n\r");

}
}
else printf("\n\r read_BLOCK failed");

}



#separate
int32 cluster_addr(int fnbr,int mode)
{
int32 address;
char buff[2]; //// buffer for 2 byte ptrs
///// returns the physical address in the data area of the data pointed to by either the
///// root cluster or the next cluster in the chain
/////
///// if ROOT_CLUSTER is called then this routine returns the address of the first cluster
///// and assigns this_cluster_ptr and next_cluster_ptr
/////
///// if NEXT_CLUSTER is called then this routine returns the address of the next cluster
///// using the existing next_cluster ptr number
///// and moves the existing next_cluster ptr number into this_cluster
///// and assigns the new next cluster ptr number (FFFF) if at the end of chain
///// if NEXT_CLUSTER is called and the next_cluster_ptr number is FFFF
///// an address of FFFFFFFF is returned

///// uses the globals cluster_size_bytes,data_area_address
//// file struct has the base=root cluster ptr, current=this cluster ptr ,next =cluster chain ptr

//// !!!! a call with NEXT_cluster must have a valid next_cluster_ptr value
//// !!!! a call to THIS CLUSTER must have a valid this_cluster_ptr

//// !!!! Fopen logic considers the cluster prt in the directory tile
//// to be a next=next_cluster_ptr so NEXT_CLUSTER is used to calc the physical address
//// of the first root cluster this also assigns the current=this_cluster_ptr
/// and fetches the next cluster prt
////
#IF MMC_CLUSTER_TRACE // if true prints to serial port
printf("\n\r cluster addr>> next_cluster_ptr= %lu this_cluster=%lu \r\n",file[fnbr].next_cluster_ptr,file[fnbr].this_cluster_ptr);
#ENDIF
if (mode==NEXT_CLUSTER)
{
///access the next cluster in the chain
/// requires a valid this_cluster_ptr number and a valid next_cluster_ptr number

if(file[fnbr].next_cluster_ptr==0xFFFF)
{
#IF MMC_CLUSTER_TRACE // if true prints to serial port
printf("last cluster");
#ENDIF
address=0XFFFFFFFF;
}
else
{
if(set_BLOCKLEN((int32)2)==false) return(35); /// set up to read 2 bytes
if(read_BLOCK(fat1_address+(file[fnbr].next_cluster_ptr)*2,buff)==false) return(33);
file[fnbr].this_cluster_ptr=file[fnbr].next_cluster_ptr; // update current with prev next in chain
file[fnbr].next_cluster_ptr=make16(buff[1],buff[0]); /// update next in chain

address=((int32)file[fnbr].this_cluster_ptr-(int32)2)*(int32)cluster_size_bytes+
data_area_address;

}
}
if (mode==ROOT_CLUSTER)
{
//// root_cluster_ptr was assigned from the file tile in fopen
file[fnbr].this_cluster_ptr=file[fnbr].root_cluster_ptr;
if(set_BLOCKLEN((int32)2)==false) return(35); /// set up to read 2 bytes
if(read_BLOCK(fat1_address+(file[fnbr].this_cluster_ptr)*2,buff)==false) return(33);
file[fnbr].next_cluster_ptr=make16(buff[1],buff[0]); /// update next in chain
address=((int32)file[fnbr].this_cluster_ptr-(int32)2)*(int32)cluster_size_bytes+
data_area_address;

}

// printf("clust addr call fnbr=%u blk_size=%lu",fnbr,file[fnbr].rec_size);

if(set_BLOCKLEN(file[fnbr].rec_size)==false) return(37); /// reset to original rec_size

#IF MMC_CLUSTER_TRACE // if true prints to serial port
printf("\n\r cluster addr>> next_cluster_ptr*= %lu this_cluster*=%lu \r\n",file[fnbr].next_cluster_ptr,file[fnbr].this_cluster_ptr);
#ENDIF return(address);
}




///////////////////////////////////////////////////////////////////////////////////
///////////////////////// OPEN FILE ///////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////
#separate
int open_file(int fnbr,char *fname,int16 rec_length)
{
int32 dir_addr_ptr;
int16 bytes_read;
int i,ptr1,ptr2,lnf_tiles;
char file_name[12];
int attribute,directory,archive;
char tmp;
char buff[32]; //// buffer for 32 byte tiles

int level; /// level in the directory structure 0 is top
/////// directory is searched and if file is found

//////
////// init_MMC(tries) must be called first
////// uses globals root_dir_address

//start by searching the root directory for folder or file

/// assign an inital next_cluster_ptr in the root directory
file[fnbr].next_cluster_ptr=0;
file[fnbr].this_cluster_ptr=0;

dir_addr_ptr=root_dir_address;
file_name[11]=0;
level=0;
ptr1=0;
ptr2=0;
bytes_read=0; //// byte read so far in this cluster

read_directory:
/// extract the directory levels(folders)
while ((fname[ptr2]!='/') && (fname[ptr2]!='\\') && (fname[ptr2]!='\0') && (fname[ptr2]!='.') )

{
// a dos directory (folder) name can not exceed 8 chars
if ((ptr2-ptr1)>7) return (20);
ptr2++;
}
#IF MMC_OPEN_TRACE
printf("\n\r fopen ptr1=%u ptr2=%u ",ptr1,ptr2);
#ENDIF

if (ptr2==0){ ptr2=1;ptr1=1;goto read_directory;} /// skip a leading '/' or '\'
if ((ptr2-ptr1)==0) return (21);

// ptr1 is the chars processed so far
// ptr2 is the position of '/' or '\' or '.' or '\0'
// prepare the file or directory name fomat is cccccccceee
// c is a valid letter or blank eee is extension or blank
// a directory name is 'cccccccc ' a file 'cccccccceee' always 11 chars
for(i=0;i<11;i++)file_name[i]=32;//blank
file_name[11]=0;
i=0;
while(ptr1<ptr2)
{
// extract the name

tmp=fname[ptr1];
tmp=TOUPPER(tmp);
file_name[i]=tmp;
ptr1++;i++;
}
if(fname[ptr2]=='.')
{
// extract the extension
i=8;
while((fname[ptr1]!='\0') && (i<12))
{
ptr1++;
tmp=fname[ptr1];
file_name[i]=TOUPPER(tmp);
i++;
}
}
ptr1++;
ptr2=ptr1; // advance over the '\' or '/' so next pass starts correctly
if (block_size!=(int32)32)
{
if(set_BLOCKLEN((int32)32)==false) return(17); /// tiles are 32 bytes
}
if (read_BLOCK(dir_addr_ptr,buff)==false) return(10);

// decode the FAT16 entries
// a tile is 32 bytes
// std dos files take one tile
// a long file name has multiple tiles
// starting with the last down to the first and
// then a std dos tile is found
// byte 11 is 0x0f for LNF tiles and 0x00 for std
// we skip the LNF and goto STD tile

tile_decode:
lnf_tiles=0;
if (buff[0]==0xE5) goto next_tile; ///0xE5 is the deleted file flag
if (buff[0]==0x00)
{
printf("\n\r file err [%s] not found \n\r",file_name);
return(11); /// file not found
}
if (buff[11]==0x0F)
{
/// get number of LNF tiles
lnf_tiles=buff[0] & 0b00111111;
bytes_read=bytes_read+lnf_tiles*32;
if(bytes_read>cluster_size_bytes)
{
// compute next cluster address next_cluster_ptr must be valid
// assigns this_cluster_ptr

dir_addr_ptr=cluster_addr(fnbr,NEXT_CLUSTER);
if (dir_addr_ptr==0xFFFFFF) return (22);
bytes_read=bytes_read-cluster_size_bytes;
dir_addr_ptr=dir_addr_ptr+bytes_read;
}
else
{
dir_addr_ptr=dir_addr_ptr+lnf_tiles*32;
}

//advance over the lnf tiles
/// test to see if we need next cluster in chain
if (read_BLOCK(dir_addr_ptr,buff)==false) return(31);
/// !!! may read into next sector
}


/// check out the standard DOS tile
#IF MMC_OPEN_TRACE
printf("\n\r fname[%s] level=%u \n\r",file_name,level);
for (j=0;j<11;j++)printf("%c",buff[j]);
#ENDIF
if(strncmp(buff,file_name, 11)==0) ///8.3 file name ex "FILE EXT"
/// "FOLDER "
{
// we have a file type or a sub directory(folder)
// so we get the starting cluster number
attribute=buff[11];

file[fnbr].root_cluster_ptr=make16(buff[27],buff[26]);/// assign initial cluster ptr
/// if it is not a directory
/// it points to the begining of the file
/// cluster chain



if ((attribute & 0b00010000)>0)directory=true;
else directory=false;
if ((attribute & 0b00100000)>0 || attribute==0)
{
archive=true; //// we have our file

file[fnbr].size=make32(buff[31],buff[30],buff[29],buff[28]);
file[fnbr].dir_addr_ptr=dir_addr_ptr; ///save address of this files tile
/// assign global value
}
else archive=false;



goto match_found;
// goto fill_table; // we have a match
}
next_tile:
bytes_read=bytes_read+32;
if(bytes_read > cluster_size_bytes)
{
/// requires a valid next=next_cluster_ptr
// compute next cluster address and assign this cluster
dir_addr_ptr=cluster_addr(fnbr,NEXT_CLUSTER);
if (dir_addr_ptr==0xFFFFFF) return (23);
bytes_read=bytes_read-cluster_size_bytes;
dir_addr_ptr=dir_addr_ptr+bytes_read;
}
else
{
dir_addr_ptr=dir_addr_ptr+32;
}


dir_addr_ptr=dir_addr_ptr+32;

if (read_BLOCK(dir_addr_ptr,buff)==false) return(32);
goto tile_decode;

match_found:
///// if we have a sub directory we need to cycle down a level
if (directory==true) {
// compute the sub directory address
// compute this cluster address this_cluster_ptr must be valid
dir_addr_ptr=cluster_addr(fnbr,ROOT_CLUSTER); /// set physical addr of starting cluster
#IF MMC_OPEN_TRACE
printf("\n\r next_cluster_ptr=%lu \n\r ",file[fnbr].next_cluster_ptr);
#ENDIF
//printf("\n\r dir_addr_ptr=%lu",dir_addr_ptr);
// dir_addr_ptr=((int32)cluster_table[0]-(int32)2)*(int32)cluster_size_bytes+
// data_area_address;
level++;
goto read_directory;
}


// note record length must divide into 512 to align properly
if (rec_length<2) return(12);



/// get the initial file_addr_ptr

file[fnbr].addr_ptr=cluster_addr(fnbr,ROOT_CLUSTER);
file[fnbr].offset=0; //init bytes read from beginning of open file
file[fnbr].cluster_offset=0; //init bytes read to beginning of the current cluster
file[fnbr].rec_size=(int32)rec_length; /// assign file record size
#IF MMC_OPEN_TRACE
printf("root_cluster=%lu \n\r",file[fnbr].root_cluster_ptr);
#ENDIF

//printf("\n\r fopen %u rec size=%lu",fnbr,file[fnbr].rec_size);

if(set_BLOCKLEN(file[fnbr].rec_size)==false) return(13);

return(0);
}

//////////////////////////////////////////////////////////////////////////////////
////////////////////////////// FILE READ ///////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////
#separate
int file_read(int8 fnbr,char *buff)
{
int32 address;
int32 nxt_cluster;
//// MMC allows a read to start and stop at any address but this file system
//// imposes a record size restriction the record size must divide into the
/// 512 block to allow writing of the records
/// rec_size must align with cluster boundary 2048 ...must be a divisor of 2048
/// find the cluster containing the offset
/// buff must be at least the size of the recordsize requested in the File open

//printf("foffset=%lu coffset=%lu ",file[fnbr].offset,file[fnbr].cluster_offset);////$$$$

if ( file[fnbr].offset>=file[fnbr].size) return(10); /// already beyond eof

if ( file[fnbr].offset + (int32) file[fnbr].rec_size > file[fnbr].cluster_offset + (int32) cluster_size_bytes)
{
#IF MMC_READ_TRACE
printf("adv to next cluster");
#ENDIF
/// need to advance to the next cluster
nxt_cluster=cluster_addr(fnbr,NEXT_CLUSTER);
if ( nxt_cluster!=0XFFFFFFFF) file[fnbr].addr_ptr=nxt_cluster;
else return(11); /// last cluster in file reached

file[fnbr].cluster_offset=file[fnbr].cluster_offset+(int32)cluster_size_bytes; //foffset is the byte offset within the file
//that file_addr_ptr points to
}
address=file[fnbr].addr_ptr+file[fnbr].offset-file[fnbr].cluster_offset;
#IF MMC_READ_TRACE
printf("\n\r offset=%lu",offset);
printf("\n\r data_area_address=%lu",data_area_address);
printf("\n\r cluster_size_bytes=%lu",cluster_size_bytes);

printf("\n\r file_addr_ptr=%lu",file_addr_ptr);
#ENDIF

if (read_BLOCK(address,buff)==false)return(12); /// read block into buff

if ( file[fnbr].offset+file[fnbr].rec_size< file[fnbr].size )
file[fnbr].offset=file[fnbr].offset+file[fnbr].rec_size;
else
{ /// end of file
#IF MMC_READ_TRACE
printf("eof size=%lu",file[fnbr].size);
#ENDIF
buff[ file[fnbr].size-file[fnbr].offset]=0; /// short record
file[fnbr].offset=file[fnbr].size;
return(255); //eof
}
return(0);

}
//////////////////////////////////////////////////////////////////////////////////
////////////////////////////// WRITE FILE /////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////
#separate
int file_write(int8 fnbr,int *buff)
{
//// buff size must be at least the recordsize requested in File open
//// the record is updated only chars beyond rec_size are ignored
/// set up for write
/// A MMC write is restricted it must be for a block and allign on block boundaries
/// blocklen must be exactly 512 and start address must be the begining of a
/// sector
/// the buff could potentially span a sector and or span a block(512) boundary
/// ex there could be 1byte left in a block and 1 byte lect in a sector
// if the block is the last block in the sector
/// worst case we could write to two blocks and need a new sector
int32 address,nxt_cluster;

int16 in_cluster_size,out_cluster_size;
int8 appending_flag;
appending_flag=0;
if (file[fnbr].offset + file[fnbr].rec_size>=file[fnbr].size) appending_flag=1;


/// find the cluster containing the offset
if ( file[fnbr].offset+file[fnbr].rec_size>=file[fnbr].cluster_offset + cluster_size_bytes)
{
#IF MMC_WRITE_TRACE
printf("spanning cluster \n\r");
#ENDIF
/// spans the current cluster so we split the write
in_cluster_size=file[fnbr].cluster_offset+cluster_size_bytes-file[fnbr].offset;
/// bytes from start of file to end of this cluste- bytes into the file
out_cluster_size=file[fnbr].rec_size - in_cluster_size;
#IF MMC_WRITE_TRACE
printf("write>> spanning cluster inside=%lu outside=%lu \n\r",in_cluster_size,out_cluster_size);
#ENDIF
address=file[fnbr].addr_ptr+file[fnbr].offset - file[fnbr].cluster_offset;
// physical address=
// physical address of the cluster +offset from begining of file
// - offset from the begining of file for the byte at the begining of the cluster
#IF MMC_WRITE_TRACE
printf("write file>>cluster=%lu in clstr addr=%lu",file[fnbr].this_cluster_ptr,address);
#ENDIF
//// address=physical offset of this cluster +bytes into this cluster
if(write_BLOCK(address,buff,in_cluster_size)==fals e)return(81); //// write first chunk



/// allocate the next cluster
nxt_cluster=cluster_addr(fnbr,NEXT_CLUSTER); ///physical address of file data that the
/// specific cluster indexes
#IF MMC_WRITE_TRACE
printf("nxt_cluster=%lu",nxt_cluster);
#ENDIF

if ( nxt_cluster==0xFFFFFFFF)

{
#IF MMC_WRITE_TRACE
printf("updating FAT");
#ENDIF
//// FAT2 is an identical copy of FAT1
file_new_cluster(fnbr,1); /// a new cluster is allocated in FAT1
file_new_cluster(fnbr,2); /// a new cluster is allocated in FAT2
nxt_cluster=cluster_addr(fnbr,NEXT_CLUSTER); ///physical address of file data that the
#IF MMC_WRITE_TRACE
printf("\n\r write>>nxt_cluster addr=%lu this clstr=%lu next=%lu",nxt_cluster,file[fnbr].this_cluster_ptr,file[fnbr].next_cluster_ptr); /// specific cluster indexes
#ENDIF
}

file[fnbr].addr_ptr =nxt_cluster;
file[fnbr].cluster_offset=file[fnbr].cluster_offset + cluster_size_bytes; //foffset is the byte offset within the file
//that file_addr_ptr points to
address=file[fnbr].addr_ptr + file[fnbr].offset - file[fnbr].cluster_offset + in_cluster_size;
#IF MMC_WRITE_TRACE
printf("out addr=%lu,out size=%lu",address,out_cluster_size);
#ENDIF
if(write_BLOCK(address,&buff[in_cluster_size],out_cluster_size)==false)return(82); /// write block pads with 0x00 to end of sector
}// end of spanned cluster
else
{
/// within the current cluster
address=file[fnbr].addr_ptr+file[fnbr].offset - file[fnbr].cluster_offset;



if(write_BLOCK(address,buff,file[fnbr].rec_size)==false)return(84); /// write block pads with 0x00 to end of sector

}
if(appending_flag==1) {
/// if appended we need to up date the file size
file[fnbr].size=file[fnbr].size + file[fnbr].rec_size; /// add one record
address=file[fnbr].dir_addr_ptr+28; /// file size is offset 28 in tiles
#IF MMC_WRITE_TRACE
printf("new file size=%lu",file[fnbr].size);
#ENDIF
buff[0]=make8(file[fnbr].size,0);
buff[1]=make8(file[fnbr].size,1);
buff[2]=make8(file[fnbr].size,2);
buff[3]=make8(file[fnbr].size,3);
MMC_dir_protected=false;
if(write_BLOCK(address,buff,4)==false)return(85);
}
if(set_BLOCKLEN(file[fnbr].rec_size)==false) return(86); /// reset to original rec_size
return(0);
}
#separate
int file_set(int fnbr,int32 offset)
{
/// file open sets the offset to the begining offset=0
/// this sets the offset within the file ...offset of 0 is a reset

if(offset>=file[fnbr].size) return(71);

file[fnbr].offset=offset; //// overwrite the existing offset
file[fnbr].next_cluster_ptr=file[fnbr].root_cluster_ptr; /// set current ptr to beginning
file[fnbr].cluster_offset=0;
// move the cluster to the one containing the offset

while ( offset>cluster_size_bytes )
{

file[fnbr].addr_ptr=cluster_addr(fnbr,NEXT_CLUSTER);
file[fnbr].cluster_offset+=cluster_size_bytes; //foffset is the byte offset within the file
if (offset-cluster_size_bytes >0) offset= offset - cluster_size_bytes;

}
return(0);
}

#separate
int file_new_cluster(int8 fnbr,int8 mode)
///////////// this does identical writes to either the FAT1 and FAT2 sectors
{
int16 eof_cluster;

char buff[2],tmp_buff[2];
int32 address;
int32 fat_address;
int16 slot;
/// an unused cluster has the value 0x0000 as its next cluster ptr
/// a used cluster has either 0xFFFF meaning last in chain
/// or a valid cluster displacement in the FAT1 amd FAT2 area
/// to append a cluster the 0XFFFF needs to be replaced by the appended
/// cluster location and the appended locations data (next ptr) needs to be set to 0XFFFF



eof_cluster=file[fnbr].this_cluster_ptr;
#IF MMC_NEW_CLUSTER
printf("the cluster with eof (FFFF)=%lu \n\r",eof_cluster);
#ENDIF

slot=0;
if(set_BLOCKLEN((int32)2)==false)return(false); // force blocklen to 2
/// use global address of FAT1 assigned by INIT
if (mode==2)fat_address=fat2_address;
else fat_address=fat1_address;
address=fat_address;

#IF MMC_NEW_CLUSTER
printf("mode=%u FAT addr=%lu \n\r",mode,address);
#ENDIF

do
{
if(read_block(address,buff)==false) return(false) ;
slot=slot+1;
address=address+2;
//printf(" slot %lu =%2x %2x",slot,buff[0],buff[1]);
}while (buff[0]!=0 || buff[1]!=0);

address=address-2; // correct for over step
slot=slot-1;


#IF MMC_NEW_CLUSTER
printf("slot=%lu address=%lu",slot,address);
#ENDIF

/// found an unused cluster
tmp_buff[0]=0xFF;tmp_buff[1]=0xFF; /// stamp it as last
MMC_dir_protected=false; /// allow writes to the protected areas
if(write_block(address,tmp_buff,2)==false ) return(false);

/////////////////////////////////////////////
/// update prev cluster with 0xFFFF in it
tmp_buff[1]=make8(slot,1);
tmp_buff[0]=make8(slot,0);
if (mode==1)
{
//// update the file info
file[fnbr].next_cluster_ptr=slot;
#IF MMC_NEW_CLUSTER
printf("cluster %lu was updated to point to %lu",file[fnbr].this_cluster_ptr,file[fnbr].next_cluster_ptr);
#ENDIF
}
/// compute physical address of the current cluster
MMC_dir_protected=false; /// allow writes to the protected areas
if(write_BLOCK(fat_address+(file[fnbr].this_cluster_ptr)*2,tmp_buff,2)==false) return(33);
if(set_BLOCKLEN((int32)file[fnbr].rec_size)==false)return(false); // reset blocklen

return(true);
}




signed int strncmp(char *s1, char *s2, int n)
{
for (; n > 0; s1++, s2++, n--)
if (*s1 != *s2)
return((*s1 <*s2) ? -1: 1);
else if (*s1 == '\0') return(0);

return(0);
}

end of the driver file mmcdos.c

below is an example of opening and reading the file HOME.HTM in the directory WEB

//#include <18F8720.h>

main()

{
int r1,i,j,error,error0,error1;
int16 rec_no;
int16 index,rec_size;
int32 offset;
char fname[32],buff0[MMC_BUFF_SIZE+1],buff1[MMC_BUFF_SIZE+1];
char c;

//int32 read_address,dir_address,dir_addr_ptr,start_lsec,
// file_addr_ptr,file_size,file_start_addr,total_byte s_read,fat1_address;
//int16 sec_resv,sec_for_FAT,start_cluster,this_cluster,ne xt_cluster,cluster_size_bytes,
// total_clusters_read,cluster_bytes_read;
//int sec_per_cluster,lnf_tiles;
printf("\n\r start mmctest");
/// init SPI interface

setup_adc_ports(NO_ANALOGS);

init_dram();

/// MMC Setup
set_tris_c(0b10010011); //c7=rx I, c6=tx O, c5 SDO O,c4 SDI I
//c3 CLK O,c2 CS O,
output_high(_CS);

/// init SPI interface
printf("\n\r Start SPI MMC\n\r");

// Note code below was needed before SPI_XMIT_LTO_H was available
// SETUP_SPI(SPI_MASTER | SPI_CLK_DIV_16 | SPI_L_TO_H );
// CKE=0;
// CKP=1;
// SMP=0;


SETUP_SPI(SPI_MASTER | SPI_CLK_DIV_16 | SPI_H_TO_L |SPI_XMIT_L_TO_H );

/// transmit on rising edge and sample receive on the rising edge
/// of the clock
/// idle clock is high

buff0[MMC_BUFF_SIZE]=0;
buff1[MMC_BUFF_SIZE]=0;
rec_no=0;



///////// init MMC ////////////////////////////////////////
error=init_MMC(10);
if (error>0) {
printf("\n\r Init failed error=%U\n\r",error);
goto mmc_exit;
}
printf("\n\r MMC initialized \n\r");
rec_size=MMC_BUFF_SIZE;
//////////////////////////////////////////////////////////////////////
// note \ is a special char in CCS so we use \\ to get a single \ (0x5C)
//strcpy(fname,"MMCTEST\\PICFILES\\PIC.TXT");
/// same as "MMCTEST\PICFILES\PIC.TXT"
///////////////////////////////////////////////////////////////////////



strcpy(fname,"WEB\\HOME.HTM");
rec_size=MMC_BUFF_SIZE;
error0=open_file(0,fname,rec_size);

if (error0>0) {
printf("\n\r fopen as 0 failed error=%U\n\r",error);
goto mmc_exit;
}
else printf("\n\r opened as 0 file %s with rec size %lu \n\r",fname,rec_size);

set_dram_address(0);




do {

error0=file_read(0,buff0);

if (error0>0 && error0<255 ) {
printf("\n\r fread 0 failed error=%U\n\r",error0);
break;
}

printf("%s",buff0);


rec_no++;

} while (error0==0);



mmc_exit:
///printf("\n\r done winhex adj= %lu \n\r",winhex_adj);



while(true);
}