main.c

一个SD卡和FAT16读写源代码

/*
 * Copyright (c) 2006-2007 by Roland Riegel <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <string.h>
#include <avr/pgmspace.h>
#include <avr/sleep.h>
#include "fat16.h"
#include "fat16_config.h"
#include "partition.h"
#include "sd_raw.h"
#include "sd_raw_config.h"
#include "uart.h"

#define DEBUG 1

/**
 * \mainpage MMC/SD card example application
 *
 * This project is a small test application which implements read and write
 * support for MMC and SD cards.
 *
 * It includes
 * - low-level \link sd_raw MMC read/write routines \endlink
 * - \link partition partition table support \endlink
 * - a simple \link fat16 FAT16 read/write implementation \endlink
 *
 * \section circuit The circuit
 * The curcuit board is a self-made and self-soldered board consisting of a single
 * copper layer and standard DIL components, except of the MMC/SD card connector.
 *
 * The connector is soldered to the bottom side of the board. It has a simple
 * eject button which, when a card is inserted, needs some space beyond the connector
 * itself. As an additional feature the connector has two electrical switches
 * to detect wether a card is inserted and wether this card is write-protected.
 * 
 * I used two microcontrollers during development, the Atmel ATmega8 with 8kBytes
 * of flash, and its pin-compatible alternative, the ATmega168 with 16kBytes flash.
 * The first one is the one I started with, but when I implemented FAT16 write
 * support, I ran out of flash space and switched to the ATmega168.
 * 
 * \section pictures Pictures
 * \image html pic01.jpg "The circuit board used to implement and test this application."
 * \image html pic02.jpg "The MMC/SD card connector on the soldering side of the circuit board."
 *
 * \section software The software
 * The software is written in pure standard ANSI-C. Sure, it might not be the
 * smallest or the fastest one, but I think it is quite flexible.
 *
 * I implemented a simple command prompt which is accessible via the UART at 9600 Baud. With
 * commands similiar to the Unix shell you can browse different directories, read and write
 * files, create new ones and delete them again. Not all commands are available in all
 * software configurations.
 * - <tt>cat \<file\></tt>\n
 *   Writes a hexdump of \<file\> to the terminal.
 * - <tt>cd \<directory\></tt>\n
 *   Changes current working directory to \<directory\>.
 * - <tt>disk</tt>\n
 *   Shows card manufacturer, status, filesystem capacity and free storage space.
 * - <tt>ls</tt>\n
 *   Shows the content of the current directory.
 * - <tt>mkdir \<directory\></tt>\n
 *   Creates a directory called \<directory\>.
 * - <tt>rm \<file\></tt>\n
 *   Deletes \<file\>.
 * - <tt>sync</tt>\n
 *   Ensures all buffered data is written to the card.
 * - <tt>touch \<file\></tt>\n
 *   Creates \<file\>.
 * - <tt>write \<file\> \<offset\></tt>\n
 *   Writes text to \<file\>, starting from \<offset\>. The text is read
 *   from the UART, line by line. Finish with an empty line.
 *
 * \htmlonly
 * <p>
 * The following table shows some typical code sizes in bytes, using the 20061101 release with malloc()/free():
 * </p>
 *
 * <table border="1" cellpadding="2">
 *     <tr>
 *         <th>layer</th>
 *         <th>code size</th>
 *         <th>static RAM usage</th>
 *     </tr>
 *     <tr>
 *         <td>MMC/SD (read-only)</td>
 *         <td align="right">1576</td>
 *         <td align="right">0</td>
 *     </tr>
 *     <tr>
 *         <td>MMC/SD (read-write)</td>
 *         <td align="right">2202</td>
 *         <td align="right">517</td>
 *     </tr>
 *     <tr>
 *         <td>Partition</td>
 *         <td align="right">418</td>
 *         <td align="right">0</td>
 *     </tr>
 *     <tr>
 *         <td>FAT16 (read-only)</td>
 *         <td align="right">3834</td>
 *         <td align="right">0</td>
 *     </tr>
 *     <tr>
 *         <td>FAT16 (read-write)</td>
 *         <td align="right">7932</td>
 *         <td align="right">0</td>
 *     </tr>
 * </table>
 *
 * <p>
 * The static RAM in the read-write case is used for buffering memory card
 * access. Without this buffer, implementation would have been much more complicated.
 * </p>
 * 
 * <p>
 * Please note that the numbers above do not include the C library functions
 * used, e.g. malloc()/free() and some string functions. These will raise the
 * numbers somewhat if they are not already used in other program parts.
 * </p>
 * 
 * <p>
 * When opening a partition, filesystem, file or directory, a little amount
 * of dynamic RAM is used, as listed in the following table. Alternatively,
 * the same amount of static RAM can be used.
 * </p>
 *
 * <table border="1" cellpadding="2">
 *     <tr>
 *         <th>descriptor</th>
 *         <th>dynamic/static RAM</th>
 *     </tr>
 *     <tr>
 *         <td>partition</td>
 *         <td align="right">17</td>
 *     </tr>
 *     <tr>
 *         <td>filesystem</td>
 *         <td align="right">26</td>
 *     </tr>
 *     <tr>
 *         <td>file</td>
 *         <td align="right">51</td>
 *     </tr>
 *     <tr>
 *         <td>directory</td>
 *         <td align="right">47</td>
 *     </tr>
 * </table>
 * 
 * \endhtmlonly
 *
 * \section adaptation Adapting the software to your needs
 * The only hardware dependent part is the communication
 * layer talking to the memory card. The other parts like partition table and FAT16
 * support are completely independent, you could use them even for managing
 * Compact Flash cards or standard ATAPI hard disks.
 *
 * By changing the MCU* variables in the Makefile, you can use other Atmel
 * microcontrollers or different clock speeds. You might also want to change
 * the configuration defines in the files fat16_config.h, partition_config.h,
 * sd_raw_config.h and sd-reader_config.h. For example, you could disable
 * write support completely if you only need read support.
 * 
 * \section bugs Bugs or comments?
 * If you have comments or found a bug in the software - there might be some
 * of them - you may contact me per mail at [e-mail].
 *
 * \section acknowledgements Acknowledgements
 * Thanks go to Ulrich Radig, who explained on his homepage how to interface
 * MMC cards to the Atmel microcontroller (http://www.ulrichradig.de/).
 * I adapted his work for my circuit. Although this is a very simple
 * solution, I had no problems using it.
 * 
 * \section copyright Copyright 2006-2007 by Roland Riegel
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation (http://www.gnu.org/copyleft/gpl.html).
 */

static uint8_t read_line(char* buffer, uint8_t buffer_length);
static uint32_t strtolong(const char* str);
static uint8_t find_file_in_dir(struct fat16_fs_struct* fs, struct fat16_dir_struct* dd, const char* name, struct fat16_dir_entry_struct* dir_entry);
static struct fat16_file_struct* open_file_in_dir(struct fat16_fs_struct* fs, struct fat16_dir_struct* dd, const char* name); 
static uint8_t print_disk_info(const struct fat16_fs_struct* fs);

int main()
{
    /* we will just use ordinary idle mode */
    set_sleep_mode(SLEEP_MODE_IDLE);

    /* setup uart */
    uart_init();

    /* setup sd card slot */
    if(!sd_raw_init())
    {
#if DEBUG
        uart_puts_p(PSTR("MMC/SD initialization failed\n"));
#endif
        return 1;
    }

    /* open first partition */
    struct partition_struct* partition = partition_open(sd_raw_read,
                                                        sd_raw_read_interval,
                                                        sd_raw_write,
                                                        sd_raw_write_interval,
                                                        0
                                                       );

    if(!partition)
    {
        /* If the partition did not open, assume the storage device
         * is a "superfloppy", i.e. has no MBR.
         */
        partition = partition_open(sd_raw_read,
                                   sd_raw_read_interval,
                                   sd_raw_write,
                                   sd_raw_write_interval,
                                   -1
                                  );
        if(!partition)
        {
#if DEBUG
            uart_puts_p(PSTR("opening partition failed\n"));
#endif
            return 1;
        }
    }

    /* open file system */
    struct fat16_fs_struct* fs = fat16_open(partition);
    if(!fs)
    {
#if DEBUG
        uart_puts_p(PSTR("opening filesystem failed\n"));
#endif
        return 1;
    }

    /* open root directory */
    struct fat16_dir_entry_struct directory;
    fat16_get_dir_entry_of_path(fs, "/", &directory);

    struct fat16_dir_struct* dd = fat16_open_dir(fs, &directory);
    if(!dd)
    {
#if DEBUG
        uart_puts_p(PSTR("opening root directory failed\n"));
#endif
        return 1;
    }
    
    /* print some card information as a boot message */
    print_disk_info(fs);

    /* provide a simple shell */
    char buffer[24];
    while(1)
    {
        /* print prompt */
        uart_putc('>');
        uart_putc(' ');

        /* read command */
        char* command = buffer;
        if(read_line(command, sizeof(buffer)) < 1)
            continue;

        /* execute command */
        if(strncmp_P(command, PSTR("cd "), 3) == 0)
        {
            command += 3;
            if(command[0] == '\0')
                continue;

            /* change directory */
            struct fat16_dir_entry_struct subdir_entry;
            if(find_file_in_dir(fs, dd, command, &subdir_entry))
            {
                struct fat16_dir_struct* dd_new = fat16_open_dir(fs, &subdir_entry);
                if(dd_new)
                {
                    fat16_close_dir(dd);
                    dd = dd_new;
                    continue;
                }
            }

            uart_puts_p(PSTR("directory not found: "));
            uart_puts(command);
            uart_putc('\n');