dataflash.c

this is a source code for usinf sd card with PIC this one is xith fat support

/*********************************************
SD Card Access Algorithms
Designed by Karl Antle
For use in ECE 402 Biomedical System Design

Note:  A char sector_array[] must be defined in an external main program

Initialize with SPI_init() and SD_reset()

Read and Write with SD_write(address) and SD_read(address)

*********************************************/
#include <mega32.h>

//These are the bits and pins that represent the SPI comms
#define SPIDI	6	// Port B bit 6 (pin7): data in (data from MMC)
#define SPIDO	5	// Port B bit 5 (pin6): data out (data to MMC)
#define SPICLK	7	// Port B bit 7 (pin8): clock
#define SPE     6
//#define MSTR    4
#define SPR1    1
#define SPR0    0
#define SPIF    7

//This is the Cable Select Pin (Slave Select) that either tells
//the SD card to ignore or proceess signals
#define CS PORTB.4

//External reference to a 512 byte array that is used to read
//and write from the SD card
extern unsigned char packet_array[];
extern unsigned int page_address, byte_address;

//Function prototypes
void SPI_init(void);
char SPI(char d);
char DF_status(void);
char DF_ready(void);
char DF_clear(void);

char DF_set_buffer2(void);
char DF_read_buff2(void);
char DF_writepacket_buff1(int time, char* datapacket);
char DF_finalize_buff1(void);


//********************************************************************
//  Function definitions
//********************************************************************

// initialize the SPI module onboard the Atmel Mega32
void SPI_init(void)
{
	//Set PORTB Tri state buffers (MISO is input all others output)
	DDRB = 0xBF;
	//Set SPI control register to MSSP, enable it, and set speed to 4MHz
	SPCR = 0x50;
	  // SPI Control - 01110000
	  // SPIE - Interrupt Enable (0)
	  // SPI - Enable (1)
	  // DORD - Data Order (0) - MSB transmitted first
	  // MSTR - Master/Slave (1) - Master
	  // CPOL - Clock Polarity (0) - SCK low when idle
	  // CPHA - Clock Phase (0) - Sample on leading edge
	  //    SPI Mode 0
	  // SPR1 SPR0 - Clock rate - f_osc/4
	//Disable SD Card
	CS = 1;
}

// send  a 8 bit character over SPI
char SPI(unsigned char d)
{
	SPDR = d;
	while(!(SPSR & 128));
	return (SPDR);
}

// get the data flash status register
char DF_status(void)
{
  char ans;

	CS = 0;  // Begin operation
	SPI(0xD7);  // ask for data
	ans = SPI(0x55);  // receive data
	CS = 1; // End operation

  return ans;
}

char DF_ready(void)
{
  return (DF_status()&128);
}

void DF_address(void){
  unsigned char c;
  c = (unsigned char) (page_address >> 6);
  SPI(c);
  c = ((unsigned char) (page_address << 2)) & ((unsigned char) (byte_address >> 8));
  SPI(c);
  c = (unsigned) byte_address;
  SPI(c);
}

char DF_clear(void){
	char c;
	int i;

  for (i=0; i<512; i++){
  	// Make sure DF is ready
  	while (!DF_ready()) {}
  	// Begin operation
  	CS = 0;
    // op-code
    SPI(0x50); // Main memory page to Buffer 2 transfer
    // address
    c = (unsigned char) (i >> 3);
    SPI(c);
    c = ((unsigned char) (page_address << 5));
    SPI(c);
    c = 0;
    SPI(c);
    // End Operation
  	CS = 1;
  }

  return 1;
}

char DF_set_buffer2(void)
{
	// Make sure DF is ready
	while (!DF_ready()) {}
	// Begin operation
	CS = 0;
  // op-code
  SPI(0x55); // Main memory page to Buffer 2 transfer
  // address
  DF_address();
  // End Operation
	CS = 1;

	return 1;
}

char DF_read_buff2(void){
  unsigned char c;
  int i;

  // Make sure DF is ready
	while (!DF_ready()) {}
	// Begin operation
	CS = 0;
  // op-code
  SPI(0xD6); // Buffer 2 read in SPI mode 0
  // address
  DF_address();
  SPI(c);   // additional don't cares
  // read data
	for(i=0; i<8; i++) {
		packet_array[i] = SPI(0x55);
	}
  // End Operation
	CS = 1;

  return 1;
}


char DF_read_buff1(void){
  unsigned char c;
  int i;

  // Make sure DF is ready
	while (!DF_ready()) {}
	// Begin operation
	CS = 0;
  // op-code
  SPI(0xD4); // Buffer 1 read in SPI mode 0
  // address
  DF_address();
  SPI(c);   // additional don't cares
  // read data
	for(i=0; i<8; i++) {
		packet_array[i] = SPI(0x55);
	}
  // End Operation
	CS = 1;

  return 1;
}



char DF_writepacket_buff1(int time, char* datapacket){
  unsigned char temp_array[5];
	int i;
	unsigned char c;

	// Copy array for transmission
  for (i=0; i<6; i++){
    temp_array[i] = datapacket[i];
  }

	// Make sure DF is ready
	while (!DF_ready()) {}
	// Begin operation
	CS = 0;
  // op-code
  SPI(0x84); // Buffer 1 Write
  // address
  DF_address();
  // send data
	SPI(8);
  SPI((time>>8));
  SPI((time<<8)>>8);
  SPI(temp_array[1]);
  SPI(temp_array[2]);
  SPI(temp_array[3]);
  SPI(temp_array[4]);
  SPI(temp_array[5]);
  // End Operation
	CS = 1;

	return 1;
}

char DF_finalize_buff1(void) {
	unsigned char c;

	// Make sure DF is ready
	while (!DF_ready()) {}
	// Begin operation
	CS = 0;
  // op-code
  SPI(0x83); // Buffer 1 to main page program with built in erase
  // address
  DF_address();
  // End Operation
	CS = 1;

	return 1;
}