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);program Mmc_Fat16_Test; const SWAP_FILE_MSG: string[15] = 'Swap file at: '; var fat_txt: string[20]; file_contents : string[50]; filename: array[14] of byte; // File names loop, loop2 : word; caracter : byte; i, size : longint; Buffer : array[512] of byte; procedure Glob_Init; begin fat_txt := 'FAT16 not found'; file_contents := 'XX MMC/SD FAT16 library by Anton Rieckert' + #10 + #0; filename := 'MIKRO00xTXT'; // File names end; //M-M-M--------- Creates new file and writes some data to it procedure M_Create_New_File; begin 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 to 99 do // We want 5 files on the MMC card begin Uart1_Write_Char('.'); file_contents[0] := (loop div 10) + 48; file_contents[1] := (loop mod 10) + 48; // Uart1_Write_Text(file_contents); Mmc_Fat_Write(file_contents, 42); // write data to the assigned file end; end;//~ //M-M-M--------- Creates many new files and writes data to them procedure M_Create_Multiple_Files; begin for loop2 := 'B' to 'Z' do begin 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 to 44 do begin file_contents[0] := (loop div 10) + 48; file_contents[1] := (loop mod 10) + 48; Mmc_Fat_Write(file_contents, 42); // write data to the assigned file end; end; end;//~ //M-M-M--------- Opens an existing file and rewrites it procedure M_Open_File_Rewrite; begin filename[7] := 'C'; Mmc_Fat_Assign(filename, 0); Mmc_Fat_Rewrite(); for loop := 1 to 55 do begin file_contents[0] := loop div 10 + 64; file_contents[1] := loop mod 10 + 64; Mmc_Fat_Write(file_contents, 42); // write data to the assigned file end; end;//~ //M-M-M--------- Opens an existing file and appends data to it // (and alters the date/time stamp) procedure M_Open_File_Append; begin 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 assigned file end;//~ //M-M-M--------- Opens an existing file, reads data from it and puts it to USART procedure M_Open_File_Read; begin filename[7] := 'B'; Mmc_Fat_Assign(filename, 0); Mmc_Fat_Reset(size); // To read file, procedure returns size of file for i := 1 to size do begin Mmc_Fat_Read(caracter); Uart1_Write_Char(caracter); // Write data to USART end; end;//~ //M-M-M--------- Deletes a file. If file doesn't exist, it will first be created // and then deleted. procedure M_Delete_File; begin filename[7] := 'F'; Mmc_Fat_Assign(filename, 0); Mmc_Fat_Delete; end;//~ //M-M-M--------- Tests whether file exists, and if so sends its creation date // and file size via USART procedure M_Test_File_Exist(fLetter: byte); var fsize: longint; year: word; month, day, hour, minute: byte; outstr: array[12] of byte; begin filename[7] := fLetter; if (Mmc_Fat_Assign(filename, 0) <> 0) then begin //--- file has been found - get its date Mmc_Fat_Get_File_Date(year, month, day, hour, minute); WordToStr(year, outstr); Uart1_Write_Text(outstr); WordToStr(month, outstr); Uart1_Write_Text(outstr); WordToStr(day, outstr); Uart1_Write_Text(outstr); WordToStr(hour, outstr); Uart1_Write_Text(outstr); WordToStr(minute, outstr); Uart1_Write_Text(outstr); //--- get file size fsize := Mmc_Fat_Get_File_Size; LongIntToStr(longint(fsize), outstr); Uart1_Write_Text(outstr); end else begin //--- file was not found - signal it Uart1_Write_Char(0x55); Delay_ms(1000); Uart1_Write_Char(0x55); end; end;//~ //-------------- Tries to create a swap file, whose size will be at least 100 // sectors (see Help for details) procedure M_Create_Swap_File; var i : word; begin for i:=0 to 511 do Buffer[i] := i; size := Mmc_Fat_Get_Swap_File(5000, 'mikroE.txt', 0x20); // see help on this function for details if (size <> 0) then begin LongIntToStr(size, fat_txt); Uart1_Write_Text(fat_txt); for i:=0 to 4999 do begin Mmc_Write_Sector(size, Buffer); Inc(size); Uart1_Write_Char('.'); end; end; end;//~ begin //-------------- Main. Uncomment the function(s) to test the desired operation(s) Glob_Init; //--- prepare PORTD for signalling PORTD := 0; TRISD := 0; ADPCFG := 0xFFFF; //--- set up USART for the file read Uart1_Init(19200); U1MODE.10 := 1; // clear the way for the SPI //--- init the FAT library 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); //--- (primary prescale := 64:1), secondary prescale := 1:1 // use fat16 quick format instead of init routine if a format is needed if (Mmc_Fat_Init(PORTB, 8) = 0) then // EasydsPIC3 board begin // 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; Uart1_Write_Char(10); M_Open_File_Rewrite; M_Open_File_Append; M_Delete_File; M_Create_Swap_File; Uart1_Write_Char(10); M_Open_File_Read; Uart1_Write_Char(10); M_Test_File_Exist('F'); // this file will not exist here Uart1_Write_Char(10); M_Test_File_Exist('B'); // this file will exist here Uart1_Write_Char(10); end else begin Uart1_Write_Text(fat_txt); end; //--- Test termination PORTD := 0xFFFF; end.//~!