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Skirmitt
Joined: 19 May 2009
Posts: 60
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| Reading data from SD card not consistent |
 Posted: Fri Oct 08, 2010 6:59 am |
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I'm struggling the whole week with reading data from a FAT formatted SD card. All I want to do is reading a file byte per byte in a loop. I succeeded in reading a file a few times but when I reset the HW I get the message that the file could not be found, after another reset it does find it and so on, mostly I get errors.
It does always fail in the MMC init function, when I bypass it and let the program go on it happens that it does read the file successfully. Weird... and I don't get it.
There is now a modified function added file_read2 to be able to read the file byte by byte. The driver is one I found on the internet from the mpic3 project, I guess Douglas Kennedy from this forum made it cause I found his name in it :-)
I feel I am close to the solution but I struggle to find it.
Main program:
| Code: | #include <18F2685.h>
#fuses NOWDT, NOPROTECT, BROWNOUT, PUT,NOLVP,INTRC_IO//,NOMCLR
#use delay(clock=8000000)
#use rs232 (baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include "HDD Driver.c"
#define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
#define SPI_MODE_1 (SPI_L_TO_H)
#define SPI_MODE_2 (SPI_H_TO_L)
#define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H)
void 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;
int16 i9=0;
int32 sizeRead=0;
output_high(_CS);
delay_ms(1000);
setup_spi(SPI_MASTER | SPI_MODE_0 | SPI_CLK_DIV_4);
buff0[MMC_BUFF_SIZE]=0;
buff1[MMC_BUFF_SIZE]=0;
rec_no=0;
///////// init MMC ////////////////////////////////////////
error=init_MMC(50);
if (error>0) {
printf("\n\rErrors in init...\n");
}
printf("\rMMC init passed...");
rec_size=MMC_BUFF_SIZE;
strcpy(fname,"idle.pcm");
rec_size=MMC_BUFF_SIZE;
error0=open_file(0,fname,rec_size);
if (error0>0) {
printf("\rfopen as 0 failed error=%U\n\r",error);
//goto mmc_exit;
}
else printf("\ropened as 0 file %s with rec size %lu \n\r",fname,rec_size);
do
{ // Lees x bytes in
sizeRead = file_read2(0,buff1);
// Overloop alle bytes
for (i9 = 0; i9 < sizeRead;i9++)
{
printf("%c",buff1[i9]);
delay_ms(50);
}
} while (sizeRead == 32);
printf("\r\nEnd of program\n\r");
//while(true);
} |
FAT driver:
| Code: |
/// PIN Assignments //////////////////////////////
#DEFINE _CS PIN_C2 // chip select for MMC
//#DEFINE SDO PIN_C5
//#DEFINE CLK PIN_C3
//#DEFINE 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 TRUE // if true prints to serial port
#define MMC_OPEN_TRACE TRUE // if true prints to serial port
#define MMC_READ_TRACE TRUE // 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
int frec_size;
int32 fat1_address; // physical address of fat1 cluster table assigned by INIT_MMC
int32 fat2_address; // physical address of fat1 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); // valid crc for 0x40 only invalid for others but spi mode doesn't care
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,invlaid 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
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;
int16 sec_resv,sec_for_FAT,bytes_per_sector,root_dir_entries,
sec_for_data,count_of_clusters,root_dir_sectors,total_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_per_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_sector;
fat2_address=fat1_address+bytes_per_sector*sec_for_FAT;
root_dir_address=(sec_for_FAT*2+start_lsec+sec_resv)*bytes_per_sector;
data_area_address=root_dir_address+root_dir_entries*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;
#if MMC_INIT_TRACE
printf("Files:/n/r");
for(i=0;i<MAX_FILES;i++){
printf("/n/r",file[i].name[i]);
}
#ENDIF
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(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_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,j;
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",cluster_offset);
printf("\n\r data_area_address=%lu",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)==false)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);
}
int32 file_read2(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(0); /// already beyond eof
if ( file[fnbr].offset + (int32) file[fnbr].rec_size > file[fnbr].cluster_offset + (int32) cluster_size_bytes){
/// 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(0); /// 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(set_BLOCKLEN((int32)MMC_BUFF_SIZE)==false)return(0); // force blocklen to 512
if (read_BLOCK(address,buff)==false)return(0); /// 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
buff[ file[fnbr].size-file[fnbr].offset]=0; /// short record
// file[fnbr].offset=file[fnbr].size;
return (file[fnbr].size - file[fnbr].offset); //eof
}
return file[fnbr].rec_size;
}
|
I use the int OSC at 32 MHz in the SD card is connected with a voltage divider.
Schematic:  instead of 1.2K I use 1.8K.
Connecting the slot straight without the dividers to my pic running at 3.3 instead of 5v makes no difference in result.
Output:
| Code: |
Errors in init...
MMC init passed...
fopen ptr1=0 ptr2=4
fname[IDLE PCM] level=0
TEST TXT
file err [IDLE PCM] not found
fopen as 0 failed error=17
End of program
|
Last edited by Skirmitt on Sat Oct 09, 2010 6:02 am; edited 1 time in total |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Fri Oct 08, 2010 12:18 pm |
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Well I wrote this code a while back ( before Microsoft had the patent ( it was initially rejected)). Some one in the UK asked for the code so I PM'd them it. Next it was posted on the web without asking me. This exposed me to potential legal issues. I took out the create file and posted it on this forum so a disclaimer could be inserted. Typically patents prevent the unauthorized creation of things so without file creation it was less an issue. I only used this code on my own PC with a Microsoft OS. I never sold any code. A change in the ruling political party in the US allowed the FAT patent be be reviewed and granted. Microsoft is the owner of FAT technology and US law requires its citizens to comply with US law irrespective of where they obtain the code. I used MMC cards and the SPI interface was open technology. Today a SD license costs approx $3000 per month and a Microsoft license $250,000 (one time).
Your issue
I'd look at the 2k resistors. MMC/SPI is fast and the pic or the MMC may not be able (at all times) to drive them high fast enough. I'd try 10k or 100k and see if your issue is resolved. At the time I used a 7407 with pull ups to level convert.
Today I'd use the CCS FAT code as they are a lawful US Corp.
Disclaimer:
I have absolutely no knowledge of Mike Luck or MPIC3.COM . I have never collaborated or had any contact with them or they with me. Unless they are the UK people that put it up on the web. This situation has had a chilling effect on me posting code to this forum.
The issue with this board is that it is has international scope. Code posted here between individuals can become commercial code offshore and if it is sold back to a US citizen it can expose the original writer and the purchaser to a commercial infringement issue. Let's hope we don't reach the situation where we have to introduce errors into code posted here so that it is essentially non working. It's harder to prove non working code does violence to the sale of working commercial code. |
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Skirmitt
Joined: 19 May 2009
Posts: 60
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| Posted: Fri Oct 08, 2010 12:44 pm |
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Hi Douglas
Thanks for your info and opinion on this code. If you want me to remove it, no problem justI give me a sign.
At the moment I only need to read a file. Next week I will also try another PIC chip, perhaps I damaged something on the SPI port. I have also the driver that Andrew S. wrote (legal purchase) but I struggle understanding it and adapting it to my needs and after asking some questions I'm a bit embarrassed to ask more.
His driver has so much options I don't see the trees through the forest, guess that sounds a bit noobish but I only have one year experience with this. Although I have knowledge of C and electronics this is a complete other level.
After fiddling with your driver I feel I learned a lot but still not enough. |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Fri Oct 08, 2010 3:46 pm |
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I prefer you remove it at least the reference to me since I in no way co-authored this with anybody.
I wrote the code so it was easier to see the FAT process in particular if the disk is viewed with win hex. At the time I needed a read only file system for a pic based web server. The pic on call back would serve image files for the web page from an MMC created on a PC. An aside ..a MMC doesn't take many ma's. A red led drops about 1.8v and will survive with up to 20ma running through it, which gets you close to the 3.3v for the mmc and a running indicator for the trouble. |
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Skirmitt
Joined: 19 May 2009
Posts: 60
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| Posted: Sat Oct 09, 2010 6:04 am |
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No problem, credits have been removed. I really hope I can get it to work. It's a bit above my head but it is so promising and rewarding this reading from SD  |
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MikeW
Joined: 15 Sep 2003
Posts: 184
Location: Warrington UK
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| Posted: Sun Oct 10, 2010 1:48 am |
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@Skirmitt,
If you find a solution, could you post it.
I also couldn't get my hardware to work with SD, and it uses the same 5V PIC, 3.3V SD, and the resistor dividers.
I put it onto the backburner a few months ago, but it would be good to find a solution.
Mike |
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Skirmitt
Joined: 19 May 2009
Posts: 60
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| Posted: Sun Oct 10, 2010 7:42 am |
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Could the problem be that I try to do this with a 2 GB card ?
Elsewhere on the forum I read that you can only use 32MB cards for these FAT16 drivers... |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Sun Oct 10, 2010 8:23 am |
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It has been discussed many times before on this forum: a PIC running at 5V and an MMC card at 3.3V are no good match. This can be solved using a voltage level converter but these chips are about the same price as choosing another PIC capable of running directly from 3.3V
The voltage divider solution is cheap but unreliable because the SDA input is a Schmitt Trigger input. According to parameter D041 of the datasheet Appendix 28.3 a Schmitt Trigger requires 0.8 * Vdd for an input level to be seen as high.
0.8 * 5V = 4V minimum
Your 3.3V MMC output is way out of specifications.
There are several solutions:
1) Preferred solution: Choose another PIC capable of running directly from 3.3V. This saves components, you can get rid of the 5V voltage regulator and the 'glue' components.
2) Insert a real voltage level translator chip.
3) Build your own level translator for MISO and keep the resistor divider for the other lines. Can be down with two transistors.
4) Don't use the hardware SPI module, but use a software emulated SPI. This way the RB0 pin can be used as a normal I/O pin which will detect a Vih level starting from 2.0V instead of the 4V for a Schmitt Trigger SDA input. |
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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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| Posted: Sun Oct 10, 2010 9:25 am |
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| Douglas Kennedy wrote: | A change in the ruling political party in the US allowed the FAT patent be be reviewed and granted. Microsoft is the owner of FAT technology and US law requires its citizens to comply with US law irrespective of where they obtain the code. I used MMC cards and the SPI interface was open technology. Today a SD license costs approx $3000 per month and a Microsoft license $250,000 (one time).
|
If Wikipedia is correct/up-to-date (http://en.wikipedia.org/wiki/File_Allocation_Table#FAT_licensing) I might offer that:
To MS, the fee is only valid if: a unit is SOLD ($0.25 each) for a maximum of $250,000.
Also, apparently the patents only apply if FAT and Long-File-Names are in use. FAT w/8.3 filenames do not constitute infringing use.
So for us home use people, develop away!
However, I am not a Lawyer. ;)
_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Sun Oct 10, 2010 11:01 am |
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| I agree home use shouldn't be an issue. However a commercial application using some other company's idea ( FAT is clearly an MS idea) without written permission is more uncertain. Whether patented or not its probably an issue if the original idea company is injured by the action. The point centers on you can't cause them to lose business. The patent often deters copying and makes it easier to win the case if it occurs. And above all it prevents another party from patenting it against you and locking you out of the use of your own idea. |
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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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| Posted: Sun Oct 10, 2010 11:22 am |
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| Douglas Kennedy wrote: | | ( FAT is clearly an MS idea) |
I would have to check that because the Patents aren't about FAT.
The LONG filenames and HOW to get them incorporated into the existing FAT DIR structures is what was patented... just like IBM has a patent for the EA DATA.SF file holding extended attrib's (like the OS/2 long filenames)
I have foggy memories from my early computer days (in the early 80's) to think that FAT as an idea was reasonably widespread enough to foible any attempts at patenting..
If Wikipedia is correct, it claims, "FAT12 was used by several manufacturers with different physical formats...."
So FAT was just another MS borrowed thing.. all they did was extend it to FAT32 (not novel) and add long filename support (USPTO seems to feel is novel).
Although again, I'm not a lawyer.. but it is interesting to contemplate.
-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Sun Oct 10, 2010 9:00 pm |
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Here are some things to consider.
If, after a reset, the software works correctly without errors and, after a reset, the software fails completely then this is an indication the card is failing to pass the initialization sequence putting the card in SPI mode. The most likely HW related causes in order of probability are:
1. The pull up resistor on DO of the card is missing or does not go where you think it does.
2. The voltage divider are the incorrect values, or reversed. The values in the schematic are correct assuming you connected it like that. If you inadvertently connected 5 volt signals to the SD/MMC card then the card is toast.
3. The 3.3volt rail has insufficient drive to deliver the peak current required by the card (usually manifests itself on write operations).
4. You do not have sufficient power supply filtering or decoupling capacitors on the 3.3volt rail. Ideally a 22uF or greater low ESR capacitor and a 0.1uF capacity should be placed as close as practical to the power pins on the MMC socket (closely related to 3 above).
The DO output of the card SHOULD be level converted to +5 volts levels in order to meed the minimum electrical requirements of the PIC SPI input level requirements however it is not uncommon for hobbyists to not use this level conversion and still be able to use the card correctly.
If you want to rule out the hardware as the source of the problem, you could try buying our low level SD/MMC utilities to test your hardware. Several of our customer buy these utilities specifically to validate their hardware.
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Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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jacqueskleynhans
Joined: 10 Apr 2008
Posts: 109
Location: Cape Town, South Africa
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| Posted: Wed Oct 20, 2010 2:17 pm |
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Why cant people just share... After all sharing is caring
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"THE ONLY EASY DAY WAS YESTERDAY" |
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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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| Posted: Wed Oct 20, 2010 2:23 pm |
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| asmallri wrote: |
4. You do not have sufficient power supply filtering or decoupling capacitors on the 3.3volt rail. Ideally a 22uF or greater low ESR capacitor and a 0.1uF capacity should be placed as close as practical to the power pins on the MMC socket (closely related to 3 above).
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I worked on software for someone's product that had an SD card -- when the SD card was plugged in, it caused a reset -- they had no recommended load switch and little capacitance on the +3.3v line running to the SD.
Interested it was.
-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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