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I have, in the code below, initialized the SD card and have found the address of the Root section. I now want to write data into the SD card. I am stuck at this point as to how should i use this info to write. I am refering to this site for information on SD card operation. I am attaching my code below.
Code:
#include <xc.h>
#include <p18cxxx.h>
#include <stdio.h>
#include <stdlib.h>
#include <plib/pconfig.h>
#include <spi.h>
void init_Device(void) //Initializes the device, setting the scialltor speed, pin direction, and pull-ups
{
OSCCON=0b01110111; //Oscillator 8 Mhz
TRISA=0; // all Port A output
TRISB=0; // all Port B output
TRISB5=1; // make serial port reception pin input
TRISB4=1; //make SDI reception pin input
TRISC=0; // all Port C output
TRISC3=1; // Make RC3 input
PEIE=1; //enable interrupts for RCIF
SBOREN=0; //disable brown out reset
}
void init_SPI(void)
{
CKP=0; //0=idle clock state is low
CKE=1; //0=Data transmitted on falling edge of SCK
SMP=1; //1=SPI mode-Input data sampled at end of data output time
SSPM3=0; //FOSC/64
SSPM2=0; //FOSC/64
SSPM1=0; //FOSC/4 - "1" for /64
SSPM0=0; //FOSC/64
}
void Delay(long x)
{
while (x>0){x--;}
}
void InitializeSPIMode(void)
{
char x; //used for "while" loops
unsigned long Address=0;
unsigned short BytesPerSector=0;
char ReservedSectors=0;
char FATCount=0;
unsigned short SectorsPerFat=0;
unsigned long FatSpace=0;
char AddressL=0; //Low byte of address
char AddressM=0; //Mid byte of address
char AddressH=0; //High byte of address
Delay(25000); //Wait one millisecond
//////////////// Slow Oscillator/SPI down for initialization ///////////////
OSCCON=0b01000111; //Oscillator 8 Mhz 0b01110111 for 8mhz
SSPM1=1; //SPI - FOSC/64
//////////////////// Initialize SPI Mode ///////////////////
Delay(1);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF); //Wake up the card (80 clock pulses)
RA5=0; Delay(5);//Assert CS
WriteSPI(0x40);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x95); //CMD0
WriteSPI(0);
WriteSPI(0);
WriteSPI(0x48);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x01);
WriteSPI(0b10101010);
WriteSPI(0x87); //CMD8
WriteSPI(0);
WriteSPI(0);
while(SSPBUF!=0) //ACMD 41 to initialize SD Card - keep doing until you get 0 meaning it's not busy
{
RA5=1; //deassert CS
Delay(5);
RA5=0; //assert CS
WriteSPI(0xFF);
WriteSPI(0b0111011);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0xFF); //CMD55
WriteSPI(0xFF);
WriteSPI(0xFF);
RA5=1; //deassert CS
RA5=0; //assert CS
WriteSPI(0xFF);
WriteSPI(0b01101001);
WriteSPI(0b00000000);
WriteSPI(0b00000000);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0xFF); //ACMD41
WriteSPI(0xFF);
WriteSPI(0xFF);
}
/////////// Speed Oscillator and SPI back up after initialization ///////////
OSCCON=0b01110111; //Oscillator 8 Mhz 0b01110111 for 8mhz
SSPM1=0;
///////////// Find Address of FAT16 Partition Entry ////////
RA5=1; //deassert CS
RA5=0; //assert CS
WriteSPI(0xFF);
WriteSPI(0b01010000);
WriteSPI(0);
WriteSPI(0);
WriteSPI(0);
WriteSPI(4);
WriteSPI(0xFF); //CMD16 4 byte block - want a return of "0"
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0b01010001);
WriteSPI(0x00);
WriteSPI(0x00);
WriteSPI(0x01);
WriteSPI(0xC6);
WriteSPI(0xFF); //CMD17 (Read Single Block) - want a response of XFE signaling that data is coming
while(SSPBUF!=0xFE) //Keep clocking until we get valid info (Follows 0xFE)
{
WriteSPI(0xFF);
}
WriteSPI(0xFF);
Address=SSPBUF; //Loads LSB of address
WriteSPI(0xFF);
Address=Address+SSPBUF*256; //loads second bytes into address
WriteSPI(0xFF);
AddressH=Address+SSPBUF*65536; //loads third bytes into address
WriteSPI(0xFF);
WriteSPI(0xFF); //two dummy blocks at end to get through check sums
WriteSPI(0xFF);
////////////// Find Address of Root //////////////
RA5=1; //deassert CS
Delay(5);
RA5=0; //assert CS
Address=Address*2; //Since address is in sectors, multiply by 2 then shift a byte over
Address=Address<<8;
AddressL=Address;
AddressM=Address>>8;
AddressH=Address>>16;
WriteSPI(0b01010000);
WriteSPI(0);
WriteSPI(0);
WriteSPI(0);
WriteSPI(13);
WriteSPI(0xFF); //CMD16 13 byte block - want a return of "0"
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0xFF);
WriteSPI(0b01010001);
WriteSPI(0);
WriteSPI(AddressH);
WriteSPI(AddressM);
WriteSPI(11);
WriteSPI(0xFF); //CMD17 (Read single Block) - want a response of XFE signaling that data is coming
while(SSPBUF!=0xFE) //Keep clocking until we get valid info (Follows 0xFE)
{
WriteSPI(0xFF);
}
WriteSPI(0xFF);
BytesPerSector=SSPBUF; //LSB of Bytes per Sector
WriteSPI(0xFF);
BytesPerSector=BytesPerSector+SSPBUF*256; //MSB of Bytes per sector
WriteSPI(0xFF); //sectors per cluster, unused
WriteSPI(0xFF);
ReservedSectors=SSPBUF; //LSB of reserved sectors
WriteSPI(0xFF); //MSB of reserved sectors (ignore)
WriteSPI(0xFF);
FATCount=SSPBUF; //number of FATs
WriteSPI(0xFF); //number of root entries, unused
WriteSPI(0xFF); //number of root entries, unused
WriteSPI(0xFF); //small sectors, unused
WriteSPI(0xFF); //small sectors, unused
WriteSPI(0xFF); //Media Type, unused
WriteSPI(0xFF);
SectorsPerFat=SSPBUF; //LSB of sectors per FAT
WriteSPI(0xFF);
SectorsPerFat=SectorsPerFat+SSPBUF*256; //MSB of sectors per FAT
WriteSPI(0xFF); //Two dummy bytes to clear the CRC
WriteSPI(0xFF);
Address=Address+BytesPerSector*ReservedSectors; //Adds the number of reserved sectors to the starting address
FatSpace=FATCount;
FatSpace=FatSpace*BytesPerSector;
FatSpace=FatSpace*SectorsPerFat;
Address=Address+FatSpace; //add FAT data space to the address to get to the root directory
/****Writing into the disk*****/
WriteSPI(0xFE);
int i;
for(i=0;i<400;i++)
WriteSPI(0xDE);
}
void main(void){
init_Device(); //initialize device
init_SPI(); //initialize SPO module
PORTA=0;
PORTB=0;
PORTC=0;
RB6=0; //Set clock to low
RA5=1; //set CS to high
InitializeSPIMode();
for(;;)
{
}
}
