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; }//~!