Revision 3:0ffb2eee9e06, committed 2011-11-11

Comitter:

samux

Date:

Fri Nov 11 16:12:21 2011 +0000

Parent:

2:27a7e7f8d399

Child:

4:980e6470dcce

Commit message:

good: we can use the sd card as mass storage device

Changed in this revision

--- a/SDcard.cpp	Fri Nov 11 15:22:53 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,197 +0,0 @@
-/* mbed Microcontroller Library - SDFileSystem
- * Copyright (c) 2008-2009, sford
- *
- * Introduction
- * ------------
- * SD and MMC cards support a number of interfaces, but common to them all
- * is one based on SPI. This is the one I'm implmenting because it means
- * it is much more portable even though not so performant, and we already 
- * have the mbed SPI Interface!
- *
- * The main reference I'm using is Chapter 7, "SPI Mode" of: 
- *  http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
- *
- * SPI Startup
- * -----------
- * The SD card powers up in SD mode. The SPI interface mode is selected by
- * asserting CS low and sending the reset command (CMD0). The card will 
- * respond with a (R1) response.
- *
- * CMD8 is optionally sent to determine the voltage range supported, and 
- * indirectly determine whether it is a version 1.x SD/non-SD card or 
- * version 2.x. I'll just ignore this for now.
- *
- * ACMD41 is repeatedly issued to initialise the card, until "in idle"
- * (bit 0) of the R1 response goes to '0', indicating it is initialised.
- *
- * You should also indicate whether the host supports High Capicity cards,
- * and check whether the card is high capacity - i'll also ignore this
- *
- * SPI Protocol
- * ------------
- * The SD SPI protocol is based on transactions made up of 8-bit words, with
- * the host starting every bus transaction by asserting the CS signal low. The
- * card always responds to commands, data blocks and errors.
- * 
- * The protocol supports a CRC, but by default it is off (except for the 
- * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
- * I'll leave the CRC off I think! 
- * 
- * Standard capacity cards have variable data block sizes, whereas High 
- * Capacity cards fix the size of data block to 512 bytes. I'll therefore
- * just always use the Standard Capacity cards with a block size of 512 bytes.
- * This is set with CMD16.
- *
- * You can read and write single blocks (CMD17, CMD25) or multiple blocks 
- * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
- * the card gets a read command, it responds with a response token, and then 
- * a data token or an error.
- * 
- * SPI Command Format
- * ------------------
- * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
- *
- * +---------------+------------+------------+-----------+----------+--------------+
- * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
- * +---------------+------------+------------+-----------+----------+--------------+
- *
- * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
- *
- * All Application Specific commands shall be preceded with APP_CMD (CMD55).
- *
- * SPI Response Format
- * -------------------
- * The main response format (R1) is a status byte (normally zero). Key flags:
- *  idle - 1 if the card is in an idle state/initialising 
- *  cmd  - 1 if an illegal command code was detected
- *
- *    +-------------------------------------------------+
- * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
- *    +-------------------------------------------------+
- *
- * R1b is the same, except it is followed by a busy signal (zeros) until
- * the first non-zero byte when it is ready again.
- *
- * Data Response Token
- * -------------------
- * Every data block written to the card is acknowledged by a byte 
- * response token
- *
- * +----------------------+
- * | xxx | 0 | status | 1 |
- * +----------------------+
- *              010 - OK!
- *              101 - CRC Error
- *              110 - Write Error
- *
- * Single Block Read and Write
- * ---------------------------
- *
- * Block transfers have a byte header, followed by the data, followed
- * by a 16-bit CRC. In our case, the data will always be 512 bytes.
- *  
- * +------+---------+---------+- -  - -+---------+-----------+----------+
- * | 0xFE | data[0] | data[1] |        | data[n] | crc[15:8] | crc[7:0] | 
- * +------+---------+---------+- -  - -+---------+-----------+----------+
- */
- 
-#include "SDcard.h"
-
-#define SD_COMMAND_TIMEOUT 5000
-
-SDcard::SDcard(PinName mosi, PinName miso, PinName sclk, PinName cs) :
-  _spi(mosi, miso, sclk), _cs(cs) {
-      _cs = 1; 
-}
-
-int SDcard::disk_write(const char *buffer, int block_number) {
-    // set write address for single block (CMD24)
-    if(_cmd(24, block_number * 512) != 0) {
-        return 1;
-    }
-
-    // send the data block
-    _write(buffer, 512);    
-    return 0;    
-}
-
-int SDcard::disk_read(char *buffer, int block_number) {        
-    // set read address for single block (CMD17)
-    if(_cmd(17, block_number * 512) != 0) {
-        return 1;
-    }
-    
-    // receive the data
-    _read(buffer, 512);
-    return 0;
-}
-
-// PRIVATE FUNCTIONS
-
-int SDcard::_cmd(int cmd, int arg) {
-    _cs = 0; 
-
-    // send a command
-    _spi.write(0x40 | cmd);
-    _spi.write(arg >> 24);
-    _spi.write(arg >> 16);
-    _spi.write(arg >> 8);
-    _spi.write(arg >> 0);
-    _spi.write(0x95);
-
-    // wait for the repsonse (response[7] == 0)
-    for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
-        int response = _spi.write(0xFF);
-        if(!(response & 0x80)) {
-            _cs = 1;
-            return response;
-        }
-    }
-    _cs = 1;
-    return -1; // timeout
-}
-
-int SDcard::_read(char *buffer, int length) {
-    _cs = 0;
-
-    // read until start byte (0xFF)
-    while(_spi.write(0xFF) != 0xFE);
-
-    // read data
-    for(int i=0; i<length; i++) {
-        buffer[i] = _spi.write(0xFF);
-    }
-    _spi.write(0xFF); // checksum
-    _spi.write(0xFF);
-
-    _cs = 1;    
-    return 0;
-}
-
-int SDcard::_write(const char *buffer, int length) {
-    _cs = 0;
-    
-    // indicate start of block
-    _spi.write(0xFE);
-    
-    // write the data
-    for(int i=0; i<length; i++) {
-        _spi.write(buffer[i]);
-    }
-    
-    // write the checksum
-    _spi.write(0xFF); 
-    _spi.write(0xFF);
-
-    // check the repsonse token
-    if((_spi.write(0xFF) & 0x1F) != 0x05) {
-        _cs = 1; 
-        return 1;
-    }
-
-    // wait for write to finish
-    while(_spi.write(0xFF) == 0);
-
-    _cs = 1; 
-    return 0;
-}

--- a/SDcard.h	Fri Nov 11 15:22:53 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,27 +0,0 @@
-/* mbed Microcontroller Library - SDFileSystem
- * Copyright (c) 2008-2009, sford
- */
-
-#ifndef SDCARD_H
-#define SDCARD_H
-
-#include "mbed.h"
-
-class SDcard
-{
-public:
-    SDcard(PinName mosi, PinName miso, PinName sclk, PinName cs);
-    virtual int disk_write(const char *buffer, int block_number);
-    virtual int disk_read(char *buffer, int block_number);   
-
-protected:
-
-    int _cmd(int cmd, int arg);
-    int _read(char *buffer, int length);
-    int _write(const char *buffer, int length);
-    
-    SPI _spi;
-    DigitalOut _cs;     
-};
-
-#endif

--- a/USBDevice/USBMSD/AT45.cpp	Fri Nov 11 15:22:53 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,829 +0,0 @@
-#include "AT45.h"
-#include "mbed.h"
-
-/* mbed Library - AT45
- * (c)2007, cstyles
- */
-
-
-
-/* 
- * Constructor
- */
-
-AT45::AT45(PinName mosi, PinName miso, PinName clk, PinName ncs) 
-    : _spi(mosi, miso, clk), _ncs(ncs) {    
-    
-    _pages = -1;       // number of pages
-    _pagesize = -1;    // size of pages 256/264, 512/528, 1024/1056
-    _devicesize = -1;  // In bytes
-
-    _buffer1address = -1;  // page address in buffer 1
-    _buffer2address = -1;  // page address in buffer 2
-    _lru = -1;             // leas recently used buffer (for eviction)
-
-    _reset();          // Populate all this stuff
-
-}
-
-    
-    
-    
-
-/* 
- * This is the reset function of the constructor.
- * Interrogate the part and set up some variables.
- */
-
-void AT45::_reset() {
-    int _id = 0;
-    int _status = 0;
-
-    _spi.format(8,0);
-    _spi.frequency(5000000);
-
-    _id = id();
-    _status = status();
-  
-    if ( (_id & 0x1f) == 0x2) { // 1Mbit
-        _devicesize = 131072; // size in bytes
-        _pages = 512;         // number of pages
-        _blocks = 256;        // Number of 512 byte blocks
-        if (_status & 0x1) {
-            _pagesize = 256;}
-        else {
-            _pagesize = 264;}    
-    }
-
-    else if ( (_id & 0x1f) == 0x3) { // 2M 
-        _devicesize = 262144; // Size in bytes
-        _pages = 1024;        // Number of pages
-        _blocks = 512;        // Number of 512 byte blocks
-        if (_status & 0x1) {
-            _pagesize = 256;}
-        else {
-            _pagesize = 264;}    
-    }
-
-    else if ( (_id & 0x1f) == 0x4) { // 4M 
-        _devicesize = 524288;
-        _pages = 2048;
-        _blocks = 1024;        // Number of 512 byte blocks
-        if (_status & 0x1) {
-            _pagesize = 256;}
-        else {
-            _pagesize = 264;}    
-    }
-
-    else if ( (_id & 0x1f) == 0x5) { // 8M 
-        _devicesize = 1048576;
-        _pages = 4096;
-        _blocks = 2048;        // Number of 512 byte blocks
-        if (_status & 0x1) {
-            _pagesize = 256;}
-        else {
-            _pagesize = 264;}    
-    }
-
-    else if ( (_id & 0x1f) == 0x6) { // 16M 
-        _devicesize = 2097152;
-        _pages = 4096;
-        _blocks = 4096;        // Number of 512 byte blocks
-        if (_status & 0x1) {
-            _pagesize = 512;}
-        else {
-            _pagesize = 528;}
-    }
-    
-    else if ( (_id & 0x1f) == 0x7) { // 32M 
-        _devicesize = 4194304;
-        _pages = 8192;
-        _blocks = 8192;        // Number of 512 byte blocks
-        if (_status & 0x1) {
-            _pagesize = 512;}
-        else {
-            _pagesize = 528;}
-    }
-    
-    else if ( (_id & 0x1f) == 0x8) { // 64M 
-        _devicesize = 8388608;
-        _pages = 8192;
-        _blocks = 16384;
-        if (_status & 0x1) {
-            _pagesize = 1024;}
-        else {
-            _pagesize = 1056;}
-    }
-    
-    else {
-        _devicesize = -1;
-        _pages = -1;
-        _pagesize = -1;
-    }
-}
-     
-
-
-
-
-/* 
- * Select pulls nCS low, but also ensure SPI channel is formatted
- * This is so that another device sharing the same SPI pins
- * doenst leave it in an unknown state
- */
-
-void AT45::_select() {
-    // ensure that the SPI port is set up correctly still
-    // This allows SPI channel sharing
-    _spi.format(8,0);
-    _spi.frequency(5000000);
-    _ncs = 0;    
-}
-    
-
-
-
-
-/* 
- * Deselect simply returns nCS to high
- */
-void AT45::_deselect() {
-    _ncs = 1;
-}
-            
-
-
-
-
-/* 
- * Work out the page address
- * If we have a 2^N page size, it is just the top N bits
- * If we have non-2^N, we use the shifted address
- */
-
-int AT45::_getpaddr(int address) {
-
-    int paddr;
-
-    if (_pagesize == 256) {                 
-        paddr = address & 0xffffff00;}    
-    else if (_pagesize == 264) {                 
-        paddr = (address << 1) & 0xfffffe00;}
-    else if (_pagesize == 512) {                 
-        paddr = address & 0xfffffe00;}
-    else if (_pagesize == 528 ) {           
-       paddr = (address << 1) & 0xfffffc00;}
-    else if (_pagesize == 1024) {                 
-       paddr = address & 0xfffffc00;}
-    else if (_pagesize == 1056 ) {           
-        paddr = (address << 1) & 0xfffff800;}
-    else {
-        paddr = 0xdeadbeef;}
-    
-    return (paddr);
- 
-}
-
-
-
-
-
-/*
- * Clean the buffer address. This is the 8/9/10 LSBs
- */
-
-int AT45::_getbaddr(int address) {
-
-    int baddr;
-
-    if ((_pagesize == 256) || (_pagesize == 264 )) {
-        baddr = address & 0xff;}
-    else if ((_pagesize == 512) || (_pagesize == 528 )) {
-        baddr = address & 0x1ff;}
-    else if ((_pagesize == 1024) || (_pagesize == 1056 )) {
-        baddr = address & 0x3ff;}
-    else {
-        baddr = 0xcafebabe;}
-
-    return (baddr);
-}
-
-
-
-
-
-/*
- * Return the Id of the part
- */
-  
-int AT45::id() { 
-    int id = 0;
-    _select();
-    _spi.write(0x9f);
-    id = (_spi.write(0x00) << 8);
-    id |= _spi.write(0x00);
-    _deselect();            
-    return id; 
-}
-
-
-
-
-
-/*
- * return the Status
- */
-
-int AT45::status() { 
-    int status = 0;
-    _select();
-    _spi.write(0xd7);
-    status = (_spi.write(0x00) << 8 );
-    status |= _spi.write(0x00);
-    _deselect();            
-    return status; 
-}
-
-
-
-
-
-/*
- * Erase the entire chip
- */
-
-void AT45::erase() { 
-
-    _pollbusy(); // make sure flash isnt already in busy.
-
-    // There are errata on this. For now, do itthe long way :-(
-    _select();
-    // 4 byte command sequence
-    _spi.write(0xc7);
-    _spi.write(0x94);
-    _spi.write(0x80);
-    _spi.write(0x9a);
-    _deselect();  
-
-    _pollbusy(); // Make erase a blocking function
-
-}
-
-
-
-
-
-/*
- * return the size of the part in bytes
- */
-
-int AT45::size() { 
-    return _devicesize;
-}
-
-
-
-
-
-/*
- * return the page size of the part in bytes
- */
-
-int AT45::pagesize() { 
-    return _pagesize;
-}
-
-
-
-
-
-/*
- * return the numbers of pages
- */
-
-int AT45::pages() { 
-    return _pages;
-}
-
-
-  
-
-
-/*
- * Make sure the Flash isnt already doing something
- */
-void AT45::_pollbusy() {
-    volatile int busy = 1;  
-    while (busy) {
-        // if bit 7 is set, we can proceed
-        if ( status() & 0x80 ) {
-            busy = 0;}
-    }
-}
-
-
-
-
-
-/*
- * Make sure the Flash isnt already doing something
- */
-
-void AT45::pollbusy() {
-    _pollbusy();
-}
-
-
-
-  
-
-/*
- * This function returns the char
- */
-
-char AT45::read(int address) {   
-    // return byte from address
-    return (_memread( address ));
-}  
-
-
-
-
-
-/*
- * This function writes the char to the address supplied
- * Note : We pass the raw address to the underlying functions
- */
-
-void AT45::write(int address, char data) {
-
-    _pollbusy();   
-    _flashread(1,address);             // read the Flash page into SRAM buffer
-    _pollbusy();                     // wait for the read to complete
-    _sramwrite(1,address,data);        // Write new data into SRAM
-    _pollbusy();                     // Make sure flash isnt busy
-    _flashwrite(1,address);            // Write back to the page address
-}
- 
-
-
-
-
-/*
- * Read from an SRAM buffer
- * Note : We create buffer and page addresses in _sram and _flash
- */
-
-int AT45::_sramread(int buffer, int address) {
-
-    int cmd = 0;
-    int baddr = 0;
-  
-    baddr = _getbaddr(address);
-  
-    _select();
-  
-    if(buffer == 1) 
-        {cmd = 0xd4;}
-    else 
-        {cmd = 0xd6;}
-  
-    _spi.write(cmd);
-    _sendaddr (baddr);
-    _spi.write (0x0);   // dont care byte
-    cmd = _spi.write (0x0);  
-  
-    _deselect();            
- 
-    return (cmd);
-}
-
-
-
-
-
-
-/*
- * Write to an SRAM buffer
- * Note : We create buffer and page addresses in _sram and _flash
- */
-
-void AT45::_sramwrite(int buffer, int address, int data) {
-
-    int cmd = 0;
-    int baddr = 0;
-  
-    baddr = _getbaddr(address);
-  
-    _pollbusy();
-  
-    _select();
-  
-    if (buffer == 1) 
-        {cmd = 0x84;}
-    else 
-        {cmd = 0x87;}
-
-    _spi.write(cmd);
-    _sendaddr (baddr);
-    _spi.write (data);  
-
-    _deselect();            
-}
-
-
-
-
-
-/*
- * Read from Flash memory into SRAM buffer
- */
-
-void AT45::_flashread (int buffer, int address) {
-
-    int cmd = 0;
-    int paddr = _getpaddr(address); // calculate page address
-  
-    _pollbusy();  // Check flash is not busy
-    _select();
-      
-    if (buffer == 1)
-        {cmd = 0x53;}
-    else
-        {cmd = 0x55;}
-
-    _spi.write (cmd);  
-    _sendaddr (paddr);
-    _deselect();            
-
-}
-
-
-
-
-
-/*
- * Write and SRAM buffer back to main memory
- */
-
-void AT45::_flashwrite (int buffer, int address) {
-
-    int cmd = 0;
-    int paddr = _getpaddr(address);
- 
-   _pollbusy();  // Check flash is not busy 
-    
-    _select();  
-
-    if (buffer == 1) 
-        {cmd = 0x83;}
-    else 
-        {cmd = 0x86;}
-      
-    _spi.write (cmd);  
-    _sendaddr (paddr);  
-    _deselect();     
-
-    _pollbusy();  // Check flash is not busy 
-  
-}
-
-
-
-
-
-/*
- * Read directly from main memory
- */
-
-int AT45::_memread (int address) {
-
-    int data = 0;        
-    int addr;
-
-    addr = _getpaddr(address) | _getbaddr(address);
-
-    _pollbusy();
-
-    _select();
-
-    _spi.write (0xd2);  // Direct read command
-    _sendaddr (addr);
-  
-    // 4 dont care bytes
-    _spi.write (0x00);  
-    _spi.write (0x00);  
-    _spi.write (0x00);  
-    _spi.write (0x00);  
-  
-    // this one clocks the data
-    data = _spi.write (0x00);  
-    _deselect();            
-
-    _pollbusy();
-
-    return data;
-}
-
-
-
-
-
-/*
- * Sends the three lest significant bytes of the supplied address
- */
-
-void AT45::_sendaddr (int address) {
-    _spi.write(address >> 16);
-    _spi.write(address >> 8);
-    _spi.write(address);      
-}
-
-
-
-
-
-/*
- * Return the number of 512 byte blocks in this device
- */
-
-int AT45::blocks(void) {  
-    return _blocks;
-}
-   
-
-
-
-
-/*
- * Read the numbered block into the data array supplied
- */
-
-int AT45::blockread (char* data, int block) {
-
-    // For 256 byte pages, we read two pages
-    if((_pagesize == 256) || (_pagesize == 264)) {
-    
-        int address = block * 512; // This is the start address of the 512 byte block
-            
-        _flashread(1,address); // read the first page of the block into SRAM buffer 1
-        _pollbusy(); // Wait until First page has loaded into buffer 1
-        
-        // I'll do this directly as we are reading back an entire buffer, and this can be done more optimally
-        // than using _sramread
-        _select();
-        _spi.write(0xd4);
-        _sendaddr (0x0);
-        _spi.write (0x0);   // dont care byte
-        
-        for(int i=0;i<256;i++) {
-            data[i] = _spi.write (0x0);  
-        }
-        _deselect();            
-                
-        _flashread(1,address+256); // read the second page of the block into SRAM buffer 2
-        _pollbusy(); // Wait until second page has loaded into buffer 2
-        
-        // Now the second page is loaded, pull this out into the second half of the data buffer
-        // I'll do this directly as we are reading back an entire buffer, and this can be done more optimally
-        // than using _sramread
-        _select();
-        _spi.write(0xd4);
-        _sendaddr (0x0);
-        _spi.write (0x0);   // dont care byte
-        
-        for(int i=0;i<256;i++) {
-            data[256+i] = _spi.write (0x0);  
-        }
-        _deselect();                
-        return (0);
-    }
-    
-    
-    // For 512 byte pages, we read just the single page, transfer it    
-    else if((_pagesize == 512) || (_pagesize == 528)) {
-
-        int address = block * 512; // This is the start address of the 512 byte block
-    
-        _pollbusy(); // Wait until First page has loaded into buffer 1
-        _flashread(1,address); // read the first page of the block into SRAM buffer 1
-        _pollbusy(); // Wait until First page has loaded into buffer 1
-        
-        // Now the page has loaded, simply transfer it from the sram buffer to the data array
-        // I'll do this directly as we are reading back an entire buffer, and this can be done more optimally
-        // than using _sramread
-        _select();
-        _spi.write(0xd4);
-        _sendaddr (0x0);
-        _spi.write (0x0);   // dont care byte
-        
-        for(int i=0;i<512;i++) {
-            data[i] = _spi.write (0x0);  
-        }
-        _deselect();            
-        return (0);
-    }
-
-
-    // For 1024 byte pages, we read just a single page, transfer half of it
-    else if((_pagesize == 1024) || (_pagesize == 1056)) {
-        int address = _getpaddr(block * 512); // This is the start address of the 512 byte block
-
-        _pollbusy(); // Wait until First page has loaded into buffer 1
-    
-        _flashread(1,address); // read the first page of the block into SRAM buffer 1
-
-        _pollbusy(); // Wait until First page has loaded into buffer 1
-        
-        // Now the page has loaded, simply transfer it from the sram buffer to the data array
-        // I'll do this directly as we are reading back an entire buffer, and this can be done more optimally
-        // than using _sramread
-
-        _select();
-        _spi.write(0xd4);
-
-        if (block %2) { // odd numbered block, read from adress 0x200
-            _sendaddr (0x200);
-        }
-        else {// even numbered block, then we are reading from sram buffer 0x0
-            _sendaddr (0x0);
-        }
-
-        
-        _spi.write (0x0);   // dont care byte
-        
-        for(int i=0;i<512;i++) {
-            data[i] = _spi.write (0x0);  
-        }
-        _deselect();            
-        return (0);
-    }
-    
-    else {
-      return (-1); // something isnt configured right
-    }
-}
-
-
-
-
-
-/*
- * Write the buffer to the numbered block
- */
-
-int AT45::blockwrite(char* data, int block) {
-
-    // For 256 byte pages, we overwrite two pages
-    if((_pagesize == 256) || (_pagesize == 264)) {
-        
-        // fill the first buffer with the first half of the block
-        // do this directly, for better performance
-        _select();
-        _spi.write(0x84); // writing to buffer #1
-        _sendaddr (0); // we are writing to the entire buffer
-
-        for(int i=0;i<256;i++) {
-            _spi.write (data[i]);  
-        }
-        _deselect();        
-                
-        _flashwrite(1,(block*512));
-
-        // fill the buffer with the second half of the block
-        // do this directly, for better performance
-        _select();
-        _spi.write(0x84); // writing to buffer #1
-        _sendaddr (0); // we are writing to the entire buffer
-
-        for(int i=0;i<256;i++) {
-            _spi.write (data[256+i]);  
-        }
-        _deselect();        
-
-        _flashwrite(1,((block*512)+256));
-    }
-    
-    
-    // For 512 byte pages, we overwrite a single page
-    else if((_pagesize == 512) || (_pagesize == 528)) {
-    
-        // fill the first buffer with the block data
-        // do this directly, for better performance
-        _select();
-        _spi.write(0x84); // writing to buffer #1
-        _sendaddr (0); // we are writing to the entire buffer
-
-        for(int i=0;i<512;i++) {
-            _spi.write (data[i]);  
-        }
-        _deselect();        
-        
-        _pollbusy(); // make sure the Flahs isnt busy
-                
-        // issue command to write buffer 1 to the appropraite flash page
-        _select();  
-        _spi.write (0x83);  
-        _sendaddr (_getpaddr(block * 512));  
-        _deselect();     
-        _pollbusy(); // make sure the Flahs isnt busy           
-    }
-
-
-    // For 1024 byte pages, we do a read modify write
-    // must make sure we overwrite the right half of the page!
-    else if((_pagesize == 1024) || (_pagesize == 1056)) {
-
-        _pollbusy(); // make sure the flash isnt busy
-
-        int address = _getpaddr(block*512);
-
-        // Read the page into sram
-        _flashread(1,address);  
-        
-        // wait for this operation to complete
-        _pollbusy();
-        
-        // Overwrite the appropriate half
-        // do this directly, for better performance
-        _select();
-        _spi.write(0x84); // writing to buffer #1
-
-        if(block%2) {  // this is an odd block number, overwrite second half of buffer
-            _sendaddr (0x200); // we are writing to the entire buffer
-        }
-        else {  // this is an even block, overwrite the first half
-            _sendaddr (0x0); // we are writing to the entire buffer
-        }
-
-        for(int i=0;i<512;i++) {
-            _spi.write (data[i]);  
-        }
-        _deselect();        
-        
-        // Write the page back
-        _pollbusy();
-        _flashwrite(1,address); 
-        
-    }
-
-
-    // Something has gone wrong
-    else {
-      return (-1);
-    }
-
-    return (0);
-}
-
-
-/*
- * Return the number of 512 byte blocks in this device
- */
-void blockerase (int block) {}
-
-
-
-/*
- * returns the number of buffer to use
- * If page is already open, use it
- * If one of the buffers is unused, use it
- * else evict the least recently used.
-
- */
-int _allocatebuffer (int address) {
-
-  int buf = 0;
-  // is page already open in buffer 1?
-  // is page already open in buffer 2
-  // is buffer 1 unusued?
-  // is buffer 2 unused
-  // evict LRU
-  
-  return (buf); 
-  
-}
-
-
-
-/*
- * write the buffer back to flash
- * set it as LRU
- * make _bufferNaddress = -1
- */
-void _flushbuffer (int buffer) {
-
-  // is page already open in buffer 1?
-  // is page already open in buffer 2
-  // is buffer 1 unusued?
-  // is buffer 2 unused
-  // evict LRU
-  
-}
-
-
-
-
-
-   
-    
\ No newline at end of file

--- a/USBDevice/USBMSD/AT45.h	Fri Nov 11 15:22:53 2011 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,103 +0,0 @@
-/* mbed Library - AT45
- * Copyright (c) 2008, cstyles
-
-
-Class to make the AT45 SPI flash parts from ATMEL appear as SRAM or 512 byte block devices
-
-This class supports 011,021,041,081,161,321,641 variants of the AT45DBxxx family
-
-|| Code || Density  || Page size || Pages || Package ||
-|| 011  || 1        || 256       || 512   || 8 SOIC  ||
-|| 021  || 2        || 256       || 1024  || 8 SOIC  ||
-|| 041  || 4        || 256       || 2048  || 8 SOIC  ||
-|| 081  || 8        || 256       || 4096  || 8 SOIC  ||
-|| 161  || 16       || 512       || 4096  || 8 SOIC  ||
-|| 321  || 32       || 512       || 8192  || 8 SOIC  ||
-|| 641  || 64       || 1024      || 8192  || 28 TSOP ||
-
-To do :
-
- - Check for current status on Erase Chip command not working.
-
- */
-
-#ifndef MBED_AT45_H
-#define MBED_AT45_H
- 
-#include "mbed.h"
-
-class AT45 {
-    
-    // Public functions
-    public:        
-
-        AT45(PinName mosi = p5, PinName miso = p6, PinName clk = p7, PinName ncs = p8);
-
-        void erase (void);
-
-        // Integer RAM access
-        char read (int address);  // read int from address. Automatically word-aligns address
-        void write (int address, char data); // Write int to address. Automatically world-aligns address
-
-        // Block device access
-        int blocks (void);  // returns the number of 512 byte blocks
-        int blockread (char* data, int block);  // read a block
-        int blockwrite (char* data, int block); // write a block
-        int blockerase (int block); // erase a block
-    
-        // Part interrogation
-        int size (void);      // Device size in bytes
-        int pages (void);      // Device size in bytes
-        int pagesize (void);      // Device size in bytes
- 
-        int id (void);        // ID of part
-        int status (void);    // Status register
-        void pollbusy (void); // Wait until Flash is not busy
-
-    // Private variables
-    private :    
-   
-        SPI _spi;
-        DigitalOut _ncs;    
-
-        int _pages;            // Integer number of pages
-        int _pagesize;         // page size, in bytes 
-        int _devicesize;       // device size in bytes
-        int _blocks;           // Number of 512 byte blocks
-    
-        // Some flags for buffering
-        int _buffer1address;
-        int _buffer2address;
-        int _lru;
-    
-        // Helper routunes
-        void _reset();
-        void _select();
-        void _deselect();
-        void _pollbusy (void);               
-    
-        // accessing SRAM buffers
-        void _sramwrite (int buffer, int address, int data);
-        int _sramread (int buffer, int address);
-    
-        // Transferring SRAM buffers to/from FLASH
-        void _flashwrite (int buffer, int paddr);
-        void _flashread (int buffer, int paddr);
-
-        // Allocate buffer
-        int _allocatebuffer(int address);
-        void _flushbuffer(int buffer);
-
-        // Reading FLASH directly
-        int _memread (int address);
-    
-        // Calculate page/subpage addresses
-        int _getpaddr (int);
-        int _getbaddr (int);
-    
-        // Send 3 byte address
-        void _sendaddr (int address);
-        
-};
-
-#endif

--- a/USBDevice/USBMSD/USBMSD.cpp	Fri Nov 11 15:22:53 2011 +0000
+++ b/USBDevice/USBMSD/USBMSD.cpp	Fri Nov 11 16:12:21 2011 +0000
@@ -38,7 +38,7 @@
 #define MAX_PACKET  MAX_PACKET_SIZE_EPBULK
 
 // memory size
-#define MemorySize  0x2000000
+#define MemorySize  0x200000
 
 //number of blocks
 #define BlockCount  (MemorySize / BlockSize)
@@ -51,7 +51,7 @@
 };
 
 
-USBMSD::USBMSD(uint16_t vendor_id, uint16_t product_id, uint16_t product_release): USBDevice(vendor_id, product_id, product_release), mem(p5, p6, p7, p8) {
+USBMSD::USBMSD(uint16_t vendor_id, uint16_t product_id, uint16_t product_release): USBDevice(vendor_id, product_id, product_release) {
 }
 
 // Called in ISR context to process a class specific request
@@ -164,7 +164,7 @@
 
     // if the array is filled, write it in memory
     if (!((addr + size)%BlockSize))
-        mem.disk_write((char *)page, addr/BlockSize);
+        blockWrite(page, addr/BlockSize);
 
     addr += size;
     length -= size;
@@ -187,7 +187,7 @@
 
     // beginning of a new block -> load a whole block in RAM
     if (!(addr%BlockSize))
-        mem.disk_read((char *)page, addr/BlockSize);
+        blockRead(page, addr/BlockSize);
 
     // info are in RAM -> no need to re-read memory
     for (n = 0; n < size; n++) {
@@ -430,7 +430,7 @@
     }
 
     if (!(addr%BlockSize))
-        mem.disk_read((char *)page, addr/BlockSize);
+        blockRead(page, addr/BlockSize);
 
     writeNB(EPBULK_IN, &page[addr%BlockSize], n, MAX_PACKET_SIZE_EPBULK);
 

--- a/USBDevice/USBMSD/USBMSD.h	Fri Nov 11 15:22:53 2011 +0000
+++ b/USBDevice/USBMSD/USBMSD.h	Fri Nov 11 16:12:21 2011 +0000
@@ -5,13 +5,14 @@
 /*
 * Guide to adapt this class to your storage chip:
 *
-* - adapt the BlockSize symbol in USBMSD.h
-* - adapt the MemorySize symbol in USBMSD.cpp
-* - declare your own object to store data: here AT45 mem
-* - Be sure to provide :
-*        - mem.blockread(page, block_number);
-*        - mem.blockwrite(page, block_number);
+* - Adapt the BlockSize symbol in USBMSD.h
+* - Adapt the MemorySize symbol in USBMSD.cpp
+* - Declare a class which inherits from USBMSD
+* - Define two virtual functions:
+*        - blockRead(uint8_t * page, uint16_t block_number);
+*        - blockWrite(uint8_t * page, uint16_t block_number);
 *    These functions are used by USBMSD class to read or write data
+* - Instanciate your object
 */
 
 #ifndef USBMSD_H
@@ -23,7 +24,6 @@
 #include "USBDevice_Types.h"
 
 #include "USBDevice.h"
-#include "SDcard.h"
 
 #define DEFAULT_CONFIGURATION (1)
 
@@ -58,21 +58,7 @@
     uint8_t  Status;
 } CSW;
 
-/**
-* USBMSD example
-*
-* @code
-* #include "mbed.h"
-* #include "USBMSD.h"
-*
-* USBMSD msd;
-*
-* int main() {
-*    while(1);
-* }
-*
-* @endcode
-*/
+
 class USBMSD: public USBDevice {
 public:
 
@@ -85,9 +71,26 @@
     */
     USBMSD(uint16_t vendor_id = 0x0703, uint16_t product_id = 0x0104, uint16_t product_release = 0x0001);
     
-
+    /*
+    * read a block on a storage chip
+    *
+    * @param data pointer where will be stored read data
+    * @param block block number
+    * @returns 0 if successful
+    */
+    virtual int blockRead(uint8_t * data, uint16_t block){return 1;};
+    
+    /*
+    * write a block on a storage chip
+    *
+    * @param data data to write
+    * @param block block number
+    * @returns 0 if successful
+    */
+    virtual int blockWrite(uint8_t * data, uint16_t block){return 1;};
+    
+protected:
 
-protected:
 
     /*
     * Get number of logical unit - 1 (here 0)
@@ -159,14 +162,6 @@
     
     // cache in RAM before writing in memory. Useful also to read a block.
     uint8_t page[BlockSize];
-    
-    // memory (Atmel AT45 family)
-    //
-    // You can change this memory to use another one (SDcard, ...)
-    // You need to provide : 
-    //    - mem.blockread(page, block_number);
-    //    - mem.blockwrite(page, block_number);
-    SDcard mem;
 
     void CBWDecode(uint8_t * buf, uint16_t size);
     void sendCSW (void);
@@ -186,4 +181,3 @@
 };
 
 #endif
-

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/USB_SDcard.cpp	Fri Nov 11 16:12:21 2011 +0000
@@ -0,0 +1,197 @@
+/* mbed Microcontroller Library - SDFileSystem
+ * Copyright (c) 2008-2009, sford
+ *
+ * Introduction
+ * ------------
+ * SD and MMC cards support a number of interfaces, but common to them all
+ * is one based on SPI. This is the one I'm implmenting because it means
+ * it is much more portable even though not so performant, and we already 
+ * have the mbed SPI Interface!
+ *
+ * The main reference I'm using is Chapter 7, "SPI Mode" of: 
+ *  http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
+ *
+ * SPI Startup
+ * -----------
+ * The SD card powers up in SD mode. The SPI interface mode is selected by
+ * asserting CS low and sending the reset command (CMD0). The card will 
+ * respond with a (R1) response.
+ *
+ * CMD8 is optionally sent to determine the voltage range supported, and 
+ * indirectly determine whether it is a version 1.x SD/non-SD card or 
+ * version 2.x. I'll just ignore this for now.
+ *
+ * ACMD41 is repeatedly issued to initialise the card, until "in idle"
+ * (bit 0) of the R1 response goes to '0', indicating it is initialised.
+ *
+ * You should also indicate whether the host supports High Capicity cards,
+ * and check whether the card is high capacity - i'll also ignore this
+ *
+ * SPI Protocol
+ * ------------
+ * The SD SPI protocol is based on transactions made up of 8-bit words, with
+ * the host starting every bus transaction by asserting the CS signal low. The
+ * card always responds to commands, data blocks and errors.
+ * 
+ * The protocol supports a CRC, but by default it is off (except for the 
+ * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
+ * I'll leave the CRC off I think! 
+ * 
+ * Standard capacity cards have variable data block sizes, whereas High 
+ * Capacity cards fix the size of data block to 512 bytes. I'll therefore
+ * just always use the Standard Capacity cards with a block size of 512 bytes.
+ * This is set with CMD16.
+ *
+ * You can read and write single blocks (CMD17, CMD25) or multiple blocks 
+ * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
+ * the card gets a read command, it responds with a response token, and then 
+ * a data token or an error.
+ * 
+ * SPI Command Format
+ * ------------------
+ * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
+ *
+ * +---------------+------------+------------+-----------+----------+--------------+
+ * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
+ * +---------------+------------+------------+-----------+----------+--------------+
+ *
+ * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
+ *
+ * All Application Specific commands shall be preceded with APP_CMD (CMD55).
+ *
+ * SPI Response Format
+ * -------------------
+ * The main response format (R1) is a status byte (normally zero). Key flags:
+ *  idle - 1 if the card is in an idle state/initialising 
+ *  cmd  - 1 if an illegal command code was detected
+ *
+ *    +-------------------------------------------------+
+ * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
+ *    +-------------------------------------------------+
+ *
+ * R1b is the same, except it is followed by a busy signal (zeros) until
+ * the first non-zero byte when it is ready again.
+ *
+ * Data Response Token
+ * -------------------
+ * Every data block written to the card is acknowledged by a byte 
+ * response token
+ *
+ * +----------------------+
+ * | xxx | 0 | status | 1 |
+ * +----------------------+
+ *              010 - OK!
+ *              101 - CRC Error
+ *              110 - Write Error
+ *
+ * Single Block Read and Write
+ * ---------------------------
+ *
+ * Block transfers have a byte header, followed by the data, followed
+ * by a 16-bit CRC. In our case, the data will always be 512 bytes.
+ *  
+ * +------+---------+---------+- -  - -+---------+-----------+----------+
+ * | 0xFE | data[0] | data[1] |        | data[n] | crc[15:8] | crc[7:0] | 
+ * +------+---------+---------+- -  - -+---------+-----------+----------+
+ */
+ 
+#include "USB_SDcard.h"
+
+#define SD_COMMAND_TIMEOUT 5000
+
+USB_SDcard::USB_SDcard(PinName mosi, PinName miso, PinName sclk, PinName cs) :
+  _spi(mosi, miso, sclk), _cs(cs) {
+      _cs = 1; 
+}
+
+int USB_SDcard::blockWrite(uint8_t * buffer, uint16_t block_number) {
+    // set write address for single block (CMD24)
+    if(_cmd(24, block_number * 512) != 0) {
+        return 1;
+    }
+
+    // send the data block
+    _write(buffer, 512);    
+    return 0;    
+}
+
+int USB_SDcard::blockRead(uint8_t * buffer, uint16_t block_number) {        
+    // set read address for single block (CMD17)
+    if(_cmd(17, block_number * 512) != 0) {
+        return 1;
+    }
+    
+    // receive the data
+    _read(buffer, 512);
+    return 0;
+}
+
+// PRIVATE FUNCTIONS
+
+int USB_SDcard::_cmd(int cmd, int arg) {
+    _cs = 0; 
+
+    // send a command
+    _spi.write(0x40 | cmd);
+    _spi.write(arg >> 24);
+    _spi.write(arg >> 16);
+    _spi.write(arg >> 8);
+    _spi.write(arg >> 0);
+    _spi.write(0x95);
+
+    // wait for the repsonse (response[7] == 0)
+    for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
+        int response = _spi.write(0xFF);
+        if(!(response & 0x80)) {
+            _cs = 1;
+            return response;
+        }
+    }
+    _cs = 1;
+    return -1; // timeout
+}
+
+int USB_SDcard::_read(uint8_t * buffer, uint16_t length) {
+    _cs = 0;
+
+    // read until start byte (0xFF)
+    while(_spi.write(0xFF) != 0xFE);
+
+    // read data
+    for(int i=0; i<length; i++) {
+        buffer[i] = _spi.write(0xFF);
+    }
+    _spi.write(0xFF); // checksum
+    _spi.write(0xFF);
+
+    _cs = 1;    
+    return 0;
+}
+
+int USB_SDcard::_write(uint8_t * buffer, uint16_t length) {
+    _cs = 0;
+    
+    // indicate start of block
+    _spi.write(0xFE);
+    
+    // write the data
+    for(int i=0; i<length; i++) {
+        _spi.write(buffer[i]);
+    }
+    
+    // write the checksum
+    _spi.write(0xFF); 
+    _spi.write(0xFF);
+
+    // check the repsonse token
+    if((_spi.write(0xFF) & 0x1F) != 0x05) {
+        _cs = 1; 
+        return 1;
+    }
+
+    // wait for write to finish
+    while(_spi.write(0xFF) == 0);
+
+    _cs = 1; 
+    return 0;
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/USB_SDcard.h	Fri Nov 11 16:12:21 2011 +0000
@@ -0,0 +1,43 @@
+/* mbed Microcontroller Library - SDFileSystem
+ * Copyright (c) 2008-2009, sford
+ */
+
+#ifndef USB_SDCARD_H
+#define USB_SDCARD_H
+
+#include "mbed.h"
+#include "USBMSD.h"
+
+class USB_SDcard: public USBMSD
+{
+public:
+    USB_SDcard(PinName mosi = p5, PinName miso = p6, PinName sclk = p7, PinName cs = p8);
+    
+    /*
+    * read a block on a storage chip
+    *
+    * @param data pointer where will be stored read data
+    * @param block block number
+    * @returns 0 if successful
+    */
+    virtual int blockRead(uint8_t * data, uint16_t block);
+    
+    /*
+    * write a block on a storage chip
+    *
+    * @param data data to write
+    * @param block block number
+    * @returns 0 if successful
+    */
+    virtual int blockWrite(uint8_t * data, uint16_t block);
+
+protected:
+    int _cmd(int cmd, int arg);
+    int _read(uint8_t * buffer, uint16_t length);
+    int _write(uint8_t * buffer, uint16_t length);
+    
+    SPI _spi;
+    DigitalOut _cs;     
+};
+
+#endif

--- a/main.cpp	Fri Nov 11 15:22:53 2011 +0000
+++ b/main.cpp	Fri Nov 11 16:12:21 2011 +0000
@@ -1,7 +1,7 @@
 #include "mbed.h"
-#include "USBMSD.h"
+#include "USB_SDcard.h"
 
-USBMSD msd;
+USB_SDcard sd;
 
 int main() {
     while(1);