Create README.md

README.md

+# SerialFlash
+
+Use SPI Flash memory with a filesystem-like interface.
+
+## Accessing Files
+
+### Open A File
+
+    SerialFlashFile file;
+    file = SerialFlash.open("filename.bin");
+    if (file) {  // true if the file exists
+
+### Read Data
+
+    char buffer[256];
+    file.read(buffer, 256);
+    
+### File Size & Positon
+
+    file.size();
+    file.position()
+    file.seek();
+    
+### Write Data
+
+    file.write(buffer, 256);
+    
+Several limitations apply to writing.  Only previously unwritten portions of the file may be written.  Files sizes can never change.  Writes may only be done within the file's original size.
+
+    file.erase();  // not yet implemented
+    
+Only files created for erasing can be erased.  The entire file is erased to all 255 (0xFF) bytes.
+    
+## Managing Files
+
+### Create New Files
+
+    SerialFlash.create(filename, size);
+    SerialFlash.createErasable(filename, size);
+    
+New files must be created using these funtions.  Each returns true if the file is successfully created, or false if not enough space is available.
+
+Once created, files can never be renamed or deleted.  The file's size can never change.  Writing additional data can NOT grow the size of file.
+
+Files created for erasing automatically increase in size to the nearest number of erasable blocks, resulting in a file that may be 4K to 128K larger than requested.
+
+### Directory Listing
+
+    SerialFlash.opendir();
+    SerialFlash.readdir(buffer, buflen, filelen);
+    
+A list of files stored in the Flash can be accessed with readdir(), which returns true for each file, or false to indicate no more files.
+
+## Full Erase
+
+    SerialFlash.erase();
+    
+    while (SerialFlash.ready() == false) {
+       // wait, 30 seconds to 2 minutes for most chips
+    }