Secure Digital (SD) is a standard flash memory card based on the earlier Multi Media Card (MMC) standard. Similarly to the CF memory cards, the SD memory cards have a high memory capacity, up to 2GB, and have found the application in the mobile phones, MP3 players, digital cameras, and PDA computers. Access to an SD memory card is realized by using the SPI communication interface.
This example consists of several blocks that demonstrat various aspects of usage of the Mmc_Fat16 library. These are: Creation of new file and writing down to it; Opening existing file and re-writing it (writing from start-of-file); Opening existing file and appending data to it (writing from end-of-file); Opening a file and reading data from it (sending it to USART terminal); Creating and modifying several files at once; Reading file contents; Deleting file(s); Creating the swap file (see Help for details);
#include <spi_const.h>
const char SWAP_FILE_MSG[] = "Swap file at: ";
char
fat_txt[20] = "FAT16 not found",
file_contents[50] = "XX MMC/SD FAT16 library by Anton Rieckertn";
char
filename[14] = "MIKRO00xTXT"; // File names
unsigned
loop, loop2;
unsigned short
caracter;
unsigned long
i, size;
char Buffer[512];
//I-I-I--------- Writes string to USART
void I_Write_Str(char *ostr) {
unsigned i;
i = 0;
while (ostr[i]) {
Uart1_Write_Char(ostr[i++]);
}
}//~
//M-M-M--------- Creates a new file and writes some data to it
void M_Create_New_File() {
filename[7] = 'A';
Mmc_Fat_Assign(&filename, 0xA0); // Will not find file and then create file
Mmc_Fat_Rewrite(); // To clear file and start with new data
for(loop = 1; loop <= 99; loop++) { // We want 5 files on the MMC card
Uart1_Write_Char('.');
file_contents[0] = loop / 10 + 48;
file_contents[1] = loop % 10 + 48;
Mmc_Fat_Write(file_contents, 42); // write data to the assigned file
}
}//~
//M-M-M--------- Creates many new files and writes data to them
void M_Create_Multiple_Files() {
for(loop2 = 'B'; loop2 <= 'Z'; loop2++) {
Uart1_Write_Char(loop2); // signal the progress
filename[7] = loop2; // set filename
Mmc_Fat_Assign(&filename, 0xA0); // find existing file or create a new one
Mmc_Fat_Rewrite(); // To clear file and start with new data
for(loop = 1; loop <= 44; loop++) {
file_contents[0] = loop / 10 + 48;
file_contents[1] = loop % 10 + 48;
Mmc_Fat_Write(file_contents, 42); // write data to the assigned file
}
}
}//~
//M-M-M--------- Opens an existing file and rewrites it
void M_Open_File_Rewrite() {
filename[7] = 'C';
Mmc_Fat_Assign(&filename, 0);
Mmc_Fat_Rewrite();
for(loop = 1; loop <= 55; loop++) {
file_contents[0] = loop / 10 + 64;
file_contents[1] = loop % 10 + 64;
Mmc_Fat_Write(file_contents, 42); // write data to the assigned file
}
}//~
//M-M-M--------- Opens an existing file and appends data to it
// (and alters the date/time stamp)
void M_Open_File_Append() {
filename[7] = 'B';
Mmc_Fat_Assign(&filename, 0);
Mmc_Fat_Set_File_Date(2005,6,21,10,35,0);
Mmc_Fat_Append(); // Prepare file for append
Mmc_Fat_Write(" for mikroElektronika 2005n", 27); // Write data to the assigned file
}//~
//M-M-M--------- Opens an existing file, reads data from it and puts it to USART
void M_Open_File_Read() {
filename[7] = 'B';
Mmc_Fat_Assign(&filename, 0);
Mmc_Fat_Reset(&size); // To read file, function returns size of file
for (i = 1; i <= size; i++) {
Mmc_Fat_Read(&caracter);
Uart1_Write_Char(caracter); // Write data to USART
}
}//~
//M-M-M--------- Deletes a file. If the file doesn't exist, it will first be created
// and then deleted.
void M_Delete_File() {
filename[7] = 'F';
Mmc_Fat_Assign(filename, 0);
Mmc_Fat_Delete();
}//~
//M-M-M--------- Tests whether file exists, and if so sends its creation date
// and file size via USART
void M_Test_File_Exist(char fLetter) {
unsigned long fsize;
unsigned int year;
unsigned short month, day, hour, minute;
unsigned char outstr[12];
filename[7] = fLetter;
if (Mmc_Fat_Assign(filename, 0)) {
//--- file has been found - get its date
Mmc_Fat_Get_File_Date(&year, &month, &day, &hour, &minute);
WordToStr(year, outstr);
I_Write_Str(outstr);
ByteToStr(month, outstr);
I_Write_Str(outstr);
WordToStr(day, outstr);
I_Write_Str(outstr);
WordToStr(hour, outstr);
I_Write_Str(outstr);
WordToStr(minute, outstr);
I_Write_Str(outstr);
//--- get file size
fsize = Mmc_Fat_Get_File_Size();
LongToStr((signed long)fsize, outstr);
I_Write_Str(outstr);
}
else {
//--- file was not found - signal it
Uart1_Write_Char(0x55);
Delay_ms(1000);
Uart1_Write_Char(0x55);
}
}//~
//-------------- Tries to create a swap file, whose size will be at least 100
// sectors (see Help for details)
void M_Create_Swap_File() {
unsigned int i;
for(i=0; i<512; i++)
Buffer[i] = i;
size = Mmc_Fat_Get_Swap_File(5000, "mikroE.txt", 0x20);
// see help on this function for details
if (size) {
LongToStr((signed long)size, fat_txt);
I_Write_Str(fat_txt);
for(i=0; i<5000; i++) {
Mmc_Write_Sector(size++, Buffer);
Uart1_Write_Char('.');
}
}
}//~
//-------------- Main. Uncomment the function(s) to test the desired operation(s)
void main() {
//--- prepare PORTD for signalling
PORTD = 0;
TRISD = 0;
ADPCFG = 0xFFFF;
//--- set up USART for the file read
Spi1_Init_Advanced(_SPI_MASTER, _SPI_8_BIT, _SPI_PRESCALE_SEC_1, _SPI_PRESCALE_PRI_64,
_SPI_SS_DISABLE, _SPI_DATA_SAMPLE_MIDDLE, _SPI_CLK_IDLE_HIGH, _SPI_ACTIVE_2_IDLE);
Uart_Init(19200);
U1MODEbits.ALTIO = 1; // clear the way for SPI
Delay_ms(200); // wait for the UART module to stabilize
//--- init the FAT library
if (!Mmc_Fat_Init(&PORTB,8)) {
// reinitialize spi at higher speed
Spi1_Init_Advanced(_SPI_MASTER, _SPI_8_BIT, _SPI_PRESCALE_SEC_1, _SPI_PRESCALE_PRI_4,
_SPI_SS_DISABLE, _SPI_DATA_SAMPLE_MIDDLE, _SPI_CLK_IDLE_HIGH, _SPI_ACTIVE_2_IDLE);
//--- Test start
PORTD = 0x0005;
//--- Test routines. Uncomment them one-by-one to test certain features
M_Create_New_File();
M_Create_Multiple_Files();
M_Open_File_Rewrite();
M_Open_File_Append();
M_Delete_File();
M_Create_Swap_File();
M_Open_File_Read();
M_Test_File_Exist('F'); // this file will not exist here
M_Test_File_Exist('B'); // this file will exist here
}
else {
I_Write_Str(fat_txt);
}
//--- Test termination
PORTD = 0xFFFF;
}//~!