Component: File (SD/SDHC Card) (File)
| Author | Matrix Ltd. |
| Version | 4.0 |
| Category | File |
File (SD/SDHC Card) component
File component allowing access to read and write files on a SD/SDHC card. Also compatible with micro SD/SDHC cards, please note the pin layout is subtely different for these.
The component automatically detects the filesystem on the card on initialise so FAT16 and FAT32 are fully supported.
When used in simulation provides read/write access to files on the local windows file system.
Detailed description
No detailed description exists yet for this component
Examples
Read a File
Initialises the FAT filesystem then checks for a file named test.txt in the root of the SD card or in the project directory for the simulation. Streams the contents of the text file to an alphanumeric display.
Write a File
Initialises the FAT filesystem then creates and opens a file before looping 20 times taking a reading from an ADC channel and writing the value to the file. The file name is log1.txt on the root of the SD card or in the project directory for the simulation.
Write a File using sectors
Not as flexible as the previous example but faster when speed is critical. Initialises the FAT filesystem then creates and opens a file before looping 5 * 128 times taking a reading from an ADC channel and writing the value to the file. The file name is log2.txt on the root of the SD card or in the project directory for the simulation. This example demonstrates high speed data logging where we place exactly 512 bytes of data (1 sector) and then call the WriteFileSector function to append the data onto file. The resulting file will have exactly 5 sectors worth of data (5 x 512 = 2560 bytes).
Macro reference
AppendByteArrayToFile
|
AppendByteArrayToFile |
| Adds a binary byte array to the end of the file.
Returns 0 for success. | |
 - BYTE
|
Data |
| Binary data array to append to the file | |
 - UINT
|
Length |
| Number of values to append | |
| - BYTE
|
Return |
AppendByteToFile
|
|
AppendByteToFile |
| Adds a single byte to the end of the currently open file, useful for inserting the value 0 into binary file types.
Returns 0 for success. | |
| - BYTE
|
Data |
| Data to append to the end of the file | |
| - BYTE
|
Return |
AppendFloatArrayToFile
|
|
AppendFloatArrayToFile |
| Adds a binary float array to the end of the file.
Returns 0 for success. | |
 - FLOAT
|
Data |
| Binary data array to append to the file | |
| - UINT
|
Length |
| Number of values to append | |
| - BYTE
|
Return |
AppendINTArrayToFile
|
|
AppendINTArrayToFile |
| Adds a binary INT array to the end of the file.
Returns 0 for success. | |
| - UINT
|
Data |
| Binary data array to append to the file | |
| - UINT
|
Length |
| Number of values to append | |
 - BOOL
|
MSBFirst |
| 0=LSB then MSB, 1=MSB then LSB | |
| - BYTE
|
Return |
AppendLongArrayToFile
|
|
AppendLongArrayToFile |
| Adds a binary Long array to the end of the file.
Returns 0 for success. | |
 - ULONG
|
Data |
| Binary data array to append to the file | |
| - UINT
|
Length |
| Number of values to append | |
| - BOOL
|
MSBFirst |
| 0=LSB then MSB, 1=MSB then LSB | |
| - BYTE
|
Return |
AppendStringToFile
|
|
AppendStringToFile |
| Adds the contents of the data string parameter to the end of the currently open file.
Returns 0 for success. | |
 - STRING
|
Data_String |
| Data to append to the end of the file | |
| - BYTE
|
Return |
CloseFile
|
|
CloseFile |
| Closes the current open file | |
 - VOID
|
Return |
CreateFile
|
|
CreateFile |
| Creates a file in the current folder location on the card. Default = Root
Returns 0 for success File must be opened using "Open_File" after creation before writing any data. | |
| - STRING
|
Filename |
| 8.3 format filename e.g."file.txt" | |
| - BYTE
|
Return |
DeleteFile
|
|
DeleteFile |
| Searches for and deletes a file in the current folder location on the card. Default = Root
Returns 0 for success. | |
| - STRING
|
Filename |
| 8.3 format filename e.g."file.txt" | |
| - BYTE
|
Return |
Initialise
|
|
Initialise |
| Attempts to communicate with the SD card and if successful sets up the file system.
Returns: 0=OK / 236 = MBR Invalid / 237 = MBR Fail / 254=No Response / 255=No Card | |
| - BYTE
|
Return |
MoveToNextFileSector
|
|
MoveToNextFileSector |
| Attempts to move to the next sector in the file.
When reading a file you would leave force next sector set to 0. When writing a file you would leave force next sector set to 1 to allow new sectors to be created as the file grows. Returns 0 for success | |
| - BYTE
|
Force_Next_Sector |
| 0 = Don't add new sector, 1 = Add new sector if we are at the end of the file | |
| - BYTE
|
Return |
OpenFile
|
|
OpenFile |
| Searches for and opens a file for reading or writing from within the current directory on the disk.
Returns 0 for success. | |
| - STRING
|
Filename |
| 8.3 filename of the file we are trying to open e.g. "file.txt" | |
| - BYTE
|
Return |
OpenFolder
|
|
OpenFolder |
| ".." - Jumps up a directory, if at root then remains in root
"root" - Jumps directly back to the root directory "foldername" - Opens folder named foldername | |
| - STRING
|
Folder_Name |
| - BYTE
|
Return |
ReadByteArrayFromFile
|
|
ReadByteArrayFromFile |
| Reads a binary byte array from the currently open file.
Auto increments the position in the file. Returns the number of values read. | |
| - BYTE
|
Data |
| Data variable to populate with data | |
| - UINT
|
Length |
| Number of values to read | |
| - UINT
|
Return |
ReadByteFromBuffer
|
|
ReadByteFromBuffer |
| Reads a byte of data from the local sector buffer.
Return = Data byte read from the local sector buffer. | |
| - UINT
|
Address |
| 0 - 511 - Contains the position of the byte to be read | |
| - BYTE
|
Return |
ReadByteFromFile
|
|
ReadByteFromFile |
| Reads a byte from the currently open file. Auto increments the position in the file.
A return value of 0 may signify the end of the file has been reached (depending on the contents of the file). | |
| - UINT
|
Return |
ReadByteFromIndex
|
|
ReadByteFromIndex |
| Reads an arbitrary byte of data from the current open file.
Return = Data byte read from the local sector buffer. | |
| - ULONG
|
Address |
| Contains the position of the byte to be read from the file | |
| - BYTE
|
Return |
ReadByteFromScan
|
|
ReadByteFromScan |
| Returns a byte of the name of the file or folder retreived from the Scan_Current_folder function.
Return = ASCII byte at position Idx from the folder name or file name at position Current_Idx in the directory | |
| - BYTE
|
idx |
| 0 - 11 for a file, 0 - 7 for a folder | |
| - BYTE
|
Return |
ReadFileLength
|
|
ReadFileLength |
| Returns the number of bytes in the current sector that are used by the current open file.
Return = 512 - Sector is filled with file data Return < 512 - Last sector of the file, Retval specifies how many bytes of data are remaining in the sector | |
 - INT
|
Return |
ReadFileSector
|
|
ReadFileSector |
| Overwrites local buffer with the current file sector from the disk.
Used to restore the local sector buffer with the actual sector stored on the card. Return = 0 : Local buffer refreshed with current card sector Return > 0 : Error | |
| - BYTE
|
Return |
ReadFileSize
|
|
ReadFileSize |
| Reads the entire size of the current file in bytes. | |
| - ULONG
|
Return |
ReadFloatArrayFromFile
|
|
ReadFloatArrayFromFile |
| Reads a binary Float array from the currently open file.
Auto increments the position in the file. Returns the number of values read. | |
| - FLOAT
|
Data |
| Data variable to populate with data | |
| - UINT
|
Length |
| Number of values to read | |
| - BOOL
|
MSBFirst |
| 0=LSB then MSB, 1=MSB then LSB | |
| - UINT
|
Return |
ReadINTArrayFromFile
|
|
ReadINTArrayFromFile |
| Reads a binary INT array from the currently open file.
Auto increments the position in the file. Returns the number of values read. | |
| - UINT
|
Data |
| Data variable to populate with data | |
| - UINT
|
Length |
| Number of values to read | |
| - BOOL
|
MSBFirst |
| 0=LSB then MSB, 1=MSB then LSB | |
| - UINT
|
Return |
ReadLongArrayFromFile
|
|
ReadLongArrayFromFile |
| Reads a binary Long array from the currently open file.
Auto increments the position in the file. Returns the number of values read. | |
| - ULONG
|
Data |
| Data variable to populate with data | |
| - UINT
|
Length |
| Number of values to read | |
| - BOOL
|
MSBFirst |
| 0=LSB then MSB, 1=MSB then LSB | |
| - UINT
|
Return |
ReadStringFromFile
|
|
ReadStringFromFile |
| Reads a string from the currently open file. Auto increments the position in the file.
An empty string signifies the end of the file has been reached. | |
| - UINT
|
NumBytes |
| Maximum number of bytes to attempt to read | |
| - BYTE
|
EndChar |
| Ends the string if the value specified is found, default is 0 | |
| - STRING
|
Return |
ScanCurrentFolder
|
|
ScanCurrentFolder |
| Method for retreiving file or folder names for the card to allow for dynamic file opening or playback. Does not currently simulate.
0 - Filetype found and stored into string array, 1 - End of folder reached, 2 - Filetype mismatch 3 - Empty | |
| - UINT
|
Current_Idx |
| Contains the current pointer in the directory table. Values from 0 to 511 to completley search the current folder for a files or folders | |
| - BYTE
|
Scan_Type |
| Sets the scan to search for Files or Folders. 0 = Scan for files, 1 = Scan for folders | |
| - BYTE
|
Return |
SetFileIndex
|
|
SetFileIndex |
| Sets the current file index and used to switch between several open file streams.
Default = 0. | |
| - BYTE
|
File_Index |
| File index ranges from 0 to (Max Concurrent Files - 1) | |
| - VOID
|
Return |
SetTimeAndDate
|
|
SetTimeAndDate |
| Sets the current time and date.
Time = (Hour << 11) + (Min << 5) + (Sec >> 1) Date = (YearFrom1980 << 9) + (Month << 5) + (Day) Additional details can be found here: http://www.maverick-os.dk/FileSystemFormats/FAT16_FileSystem.html#TimeFormat | |
| - UINT
|
Time |
| Sets the current Time in FAT Time format hhhhhmmmmmmsssss - S=Secs/2 | |
| - UINT
|
Date |
| Sets the current Date in FAT Date format yyyyyyymmmmddddd - Y=Years since 1980 | |
| - VOID
|
Return |
UpdateFileSector
|
|
UpdateFileSector |
| Updates a file sector with new data set from using WriteByteToBuffer.
Note this cannot alter the size of the file. | |
| - VOID
|
Return |
WriteByteToBuffer
|
|
WriteByteToBuffer |
| Writes a single byte to the current 512 byte local sector buffer. | |
| - UINT
|
Address |
| Address Range 0 - 511 | |
| - BYTE
|
Data |
| Data Byte to write to the buffer | |
| - VOID
|
Return |
WriteFileSector
|
|
WriteFileSector |
| Overwrites the current sector on the memory card with the contents of the local sector buffer. See write_byte_to_buffer function.
Return = 0 - File sector written successfully. Return > 0 - File sector write error | |
| - BYTE
|
Return |
Property reference
|
Properties |
|
Connections |
|
Channel |
| SPI Channel selector | |
|
MOSI |
| SPI Data Out Pin SDO - Also Known as Master Out Slave In (MOSI) when used in Master mode. | |
|
|
MISO |
| SPI Data In Pin SDI - Also Known as Master In Slave Out (MISO) when used in Master mode. | |
|
|
CLK |
| SPI Clock Pin CLK - The Clock signal is driven by the SPI master. | |
|
|
CS / SS |
| Chip Select / Slave Select Pin
Master Mode: General purpose output pin used to select the remote SPI device. Slave Mode: Hardware chip select pin input used to select the SPI device. | |
|
|
Initial Prescaler |
| SPI initial clock divider - Frequency should be under 400khz to allow startup to work correctly.
| |
|
|
High Speed Prescaler |
| SPI high speed clock divider - Once startup is complete this is the rate that will be used to transfer data | |
|
|
File System |
|
Max Concurrent Files |
| Specifies how many concurrent files can be opened at any one time.
Use the SetFileIndex macro to switch between concurrent files. | |
|
|
End Of File |
| Specifies the way the ReadByteFromFile function indicates the end of a file.
8 Bit mode - End of the file is represented by the value 0, read multiple times to confirm that the 0 is not simply data. 16 Bit mode - End of file is represented by the value 512 allowing the values 0 - 255 to represent valid data. | |
|
|
Simulation |
|
|
Sim Type |
| Defines the simulation type.
The default is to use the Windows file system to allow for reading and writing files. The alternative is to use the CAL functionality to allow the SPI transactions to be passed onto a seperate handler e.g. for logging or debugging purposes. | |
|
|
File System |
|
Root Directory |
| Directory flagged as root for simulation Default: $(srcdir) is the current project source directory.
Modern windows systems do not like you writing files to a hard drive root directory so a directory off the root is advised. | |
Component Source Code
Please click here to download the component source project: FC_Comp_Source_File_SD_FAT.fcfx
Please click here to view the component source code (Beta): FC_Comp_Source_File_SD_FAT.fcfx