SDHCFileSystem.cpp

00001 /* mbed SDFileSystem Library, for providing file access to SD cards
00002  * Copyright (c) 2008-2010, sford
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022 
00023 /* Introduction
00024  * ------------
00025  * SD and MMC cards support a number of interfaces, but common to them all
00026  * is one based on SPI. This is the one I'm implmenting because it means
00027  * it is much more portable even though not so performant, and we already 
00028  * have the mbed SPI Interface!
00029  *
00030  * The main reference I'm using is Chapter 7, "SPI Mode" of: 
00031  *  http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
00032  *
00033  * SPI Startup
00034  * -----------
00035  * The SD card powers up in SD mode. The SPI interface mode is selected by
00036  * asserting CS low and sending the reset command (CMD0). The card will 
00037  * respond with a (R1) response.
00038  *
00039  * CMD8 is optionally sent to determine the voltage range supported, and 
00040  * indirectly determine whether it is a version 1.x SD/non-SD card or 
00041  * version 2.x. I'll just ignore this for now.
00042  *
00043  * ACMD41 is repeatedly issued to initialise the card, until "in idle"
00044  * (bit 0) of the R1 response goes to '0', indicating it is initialised.
00045  *
00046  * You should also indicate whether the host supports High Capicity cards,
00047  * and check whether the card is high capacity - i'll also ignore this
00048  *
00049  * SPI Protocol
00050  * ------------
00051  * The SD SPI protocol is based on transactions made up of 8-bit words, with
00052  * the host starting every bus transaction by asserting the CS signal low. The
00053  * card always responds to commands, data blocks and errors.
00054  * 
00055  * The protocol supports a CRC, but by default it is off (except for the 
00056  * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
00057  * I'll leave the CRC off I think! 
00058  * 
00059  * Standard capacity cards have variable data block sizes, whereas High 
00060  * Capacity cards fix the size of data block to 512 bytes. I'll therefore
00061  * just always use the Standard Capacity cards with a block size of 512 bytes.
00062  * This is set with CMD16.
00063  *
00064  * You can read and write single blocks (CMD17, CMD25) or multiple blocks 
00065  * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
00066  * the card gets a read command, it responds with a response token, and then 
00067  * a data token or an error.
00068  * 
00069  * SPI Command Format
00070  * ------------------
00071  * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
00072  *
00073  * +---------------+------------+------------+-----------+----------+--------------+
00074  * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
00075  * +---------------+------------+------------+-----------+----------+--------------+
00076  *
00077  * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
00078  *
00079  * All Application Specific commands shall be preceded with APP_CMD (CMD55).
00080  *
00081  * SPI Response Format
00082  * -------------------
00083  * The main response format (R1) is a status byte (normally zero). Key flags:
00084  *  idle - 1 if the card is in an idle state/initialising 
00085  *  cmd  - 1 if an illegal command code was detected
00086  *
00087  *    +-------------------------------------------------+
00088  * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
00089  *    +-------------------------------------------------+
00090  *
00091  * R1b is the same, except it is followed by a busy signal (zeros) until
00092  * the first non-zero byte when it is ready again.
00093  *
00094  * Data Response Token
00095  * -------------------
00096  * Every data block written to the card is acknowledged by a byte 
00097  * response token
00098  *
00099  * +----------------------+
00100  * | xxx | 0 | status | 1 |
00101  * +----------------------+
00102  *              010 - OK!
00103  *              101 - CRC Error
00104  *              110 - Write Error
00105  *
00106  * Single Block Read and Write
00107  * ---------------------------
00108  *
00109  * Block transfers have a byte header, followed by the data, followed
00110  * by a 16-bit CRC. In our case, the data will always be 512 bytes.
00111  *  
00112  * +------+---------+---------+- -  - -+---------+-----------+----------+
00113  * | 0xFE | data[0] | data[1] |        | data[n] | crc[15:8] | crc[7:0] | 
00114  * +------+---------+---------+- -  - -+---------+-----------+----------+
00115  */
00116  
00117  /*
00118  * Comment: Changes for SDHC support till 32GB 
00119  * Name:    KB
00120  * Date:    07/24/2010
00121  * Release: 0.1
00122  */
00123  
00124  /*
00125  * Comment: Fixing compiler warnings, turning off DEBUG define
00126  * Name:    davervw
00127  * Date:    02/26/2011
00128  */
00129 
00130 #include "SDHCFileSystem.h"
00131 
00132 //#define DEBUG
00133 #define SD_COMMAND_TIMEOUT 5000
00134 
00135 
00136 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
00137   FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
00138       _cs = 1; 
00139 }
00140 
00141 #define R1_IDLE_STATE           (1 << 0)
00142 #define R1_ERASE_RESET          (1 << 1)
00143 #define R1_ILLEGAL_COMMAND      (1 << 2)
00144 #define R1_COM_CRC_ERROR        (1 << 3)
00145 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
00146 #define R1_ADDRESS_ERROR        (1 << 5)
00147 #define R1_PARAMETER_ERROR      (1 << 6)
00148 
00149 // Types
00150 //  - v1.x Standard Capacity
00151 //  - v2.x Standard Capacity
00152 //  - v2.x High Capacity
00153 //  - Not recognised as an SD Card
00154 
00155 #define SDCARD_FAIL 0
00156 #define SDCARD_V1   1
00157 #define SDCARD_V2   2
00158 #define SDCARD_V2HC 3
00159 
00160 int SDFileSystem::initialise_card() {
00161     // Set to 100kHz for initialisation, and clock card with cs = 1
00162     _spi.frequency(100000); 
00163     _cs = 1;
00164     for(int i=0; i<16; i++) {   
00165         _spi.write(0xFF);
00166     }
00167 
00168     // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
00169     if(_cmd(0, 0) != R1_IDLE_STATE) { 
00170         fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n");
00171         return SDCARD_FAIL;
00172     }
00173 
00174     // send CMD8 to determine whther it is ver 2.x
00175     int r = _cmd8();
00176     if(r == R1_IDLE_STATE) {
00177         return initialise_card_v2();
00178     } else if(r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
00179         return initialise_card_v1();
00180     } else {
00181         fprintf(stderr, "Not in idle state after sending CMD8 (not an SD card?)\n");
00182         return SDCARD_FAIL;
00183     }
00184 }
00185 
00186 int SDFileSystem::initialise_card_v1() {
00187     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00188         _cmd(55, 0); 
00189         if(_cmd(41, 0) == 0) { 
00190             cdv = 512;
00191             #ifdef DEBUG 
00192             printf("\n\rInit: SEDCARD_V1\n\r");
00193             #endif
00194             return SDCARD_V1;
00195         }
00196     }
00197 
00198     fprintf(stderr, "Timeout waiting for v1.x card\n");
00199     return SDCARD_FAIL;
00200 }
00201 
00202 int SDFileSystem::initialise_card_v2() {
00203     
00204     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00205         wait_ms(50);
00206         _cmd58();
00207         _cmd(55, 0); 
00208         if(_cmd(41, 0x40000000) == 0) { 
00209             _cmd58();
00210             #ifdef DEBUG
00211             printf("\n\rInit: SDCARD_V2\n\r");
00212             #endif
00213             cdv = 1;
00214             return SDCARD_V2;
00215         }
00216     }
00217 
00218     fprintf(stderr, "Timeout waiting for v2.x card\n");
00219     return SDCARD_FAIL;
00220 }
00221 
00222 int SDFileSystem::disk_initialize() {
00223 
00224     int i = initialise_card();
00225     #ifdef DEBUG 
00226     printf("init card = %d\n", i);
00227     #endif
00228     _sectors = _sd_sectors();
00229 
00230     // Set block length to 512 (CMD16)
00231     if(_cmd(16, 512) != 0) {
00232         fprintf(stderr, "Set 512-byte block timed out\n");
00233         return 1;
00234     }
00235         
00236     _spi.frequency(1000000); // Set to 1MHz for data transfer
00237     return 0;
00238 }
00239 
00240 int SDFileSystem::disk_write(const char *buffer, int block_number) {
00241     // set write address for single block (CMD24)
00242     if(_cmd(24, block_number * cdv) != 0) {
00243         return 1;
00244     }
00245 
00246     // send the data block
00247     _write(buffer, 512);    
00248     return 0;    
00249 }
00250 
00251 int SDFileSystem::disk_read(char *buffer, int block_number) {        
00252     // set read address for single block (CMD17)
00253     if(_cmd(17, block_number * cdv) != 0) {
00254         return 1;
00255     }
00256     
00257     // receive the data
00258     _read(buffer, 512);
00259     return 0;
00260 }
00261 
00262 int SDFileSystem::disk_status() { return 0; }
00263 int SDFileSystem::disk_sync() { return 0; }
00264 int SDFileSystem::disk_sectors() { return _sectors; }
00265 
00266 // PRIVATE FUNCTIONS
00267 
00268 int SDFileSystem::_cmd(int cmd, int arg) {
00269     _cs = 0; 
00270 
00271     // send a command
00272     _spi.write(0x40 | cmd);
00273     _spi.write(arg >> 24);
00274     _spi.write(arg >> 16);
00275     _spi.write(arg >> 8);
00276     _spi.write(arg >> 0);
00277     _spi.write(0x95);
00278 
00279     // wait for the repsonse (response[7] == 0)
00280     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00281         int response = _spi.write(0xFF);
00282         if(!(response & 0x80)) {
00283             _cs = 1;
00284             _spi.write(0xFF);
00285             return response;
00286         }
00287     }
00288     _cs = 1;
00289     _spi.write(0xFF);
00290     return -1; // timeout
00291 }
00292 int SDFileSystem::_cmdx(int cmd, int arg) {
00293     _cs = 0; 
00294 
00295     // send a command
00296     _spi.write(0x40 | cmd);
00297     _spi.write(arg >> 24);
00298     _spi.write(arg >> 16);
00299     _spi.write(arg >> 8);
00300     _spi.write(arg >> 0);
00301     _spi.write(0x95);
00302 
00303     // wait for the repsonse (response[7] == 0)
00304     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00305         int response = _spi.write(0xFF);
00306         if(!(response & 0x80)) {
00307             return response;
00308         }
00309     }
00310     _cs = 1;
00311     _spi.write(0xFF);
00312     return -1; // timeout
00313 }
00314 
00315 
00316 int SDFileSystem::_cmd58() {
00317     _cs = 0; 
00318     int arg = 0;
00319     
00320     // send a command
00321     _spi.write(0x40 | 58);
00322     _spi.write(arg >> 24);
00323     _spi.write(arg >> 16);
00324     _spi.write(arg >> 8);
00325     _spi.write(arg >> 0);
00326     _spi.write(0x95);
00327 
00328     // wait for the repsonse (response[7] == 0)
00329     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00330         int response = _spi.write(0xFF);
00331         if(!(response & 0x80)) {
00332             int ocr = _spi.write(0xFF) << 24;
00333             ocr |= _spi.write(0xFF) << 16;
00334             ocr |= _spi.write(0xFF) << 8;
00335             ocr |= _spi.write(0xFF) << 0;
00336 //            printf("OCR = 0x%08X\n", ocr);
00337             _cs = 1;
00338             _spi.write(0xFF);
00339             return response;
00340         }
00341     }
00342     _cs = 1;
00343     _spi.write(0xFF);
00344     return -1; // timeout
00345 }
00346 
00347 int SDFileSystem::_cmd8() {
00348     _cs = 0; 
00349     
00350     // send a command
00351     _spi.write(0x40 | 8); // CMD8
00352     _spi.write(0x00);     // reserved
00353     _spi.write(0x00);     // reserved
00354     _spi.write(0x01);     // 3.3v
00355     _spi.write(0xAA);     // check pattern
00356     _spi.write(0x87);     // crc
00357 
00358     // wait for the repsonse (response[7] == 0)
00359     for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
00360         char response[5];
00361         response[0] = _spi.write(0xFF);
00362         if(!(response[0] & 0x80)) {
00363                 for(int j=1; j<5; j++) {
00364                     response[i] = _spi.write(0xFF);
00365                 }
00366                 _cs = 1;
00367                 _spi.write(0xFF);
00368                 return response[0];
00369         }
00370     }
00371     _cs = 1;
00372     _spi.write(0xFF);
00373     return -1; // timeout
00374 }
00375 
00376 int SDFileSystem::_read(char *buffer, int length) {
00377     _cs = 0;
00378 
00379     // read until start byte (0xFF)
00380     while(_spi.write(0xFF) != 0xFE);
00381 
00382     // read data
00383     for(int i=0; i<length; i++) {
00384         buffer[i] = _spi.write(0xFF);
00385     }
00386     _spi.write(0xFF); // checksum
00387     _spi.write(0xFF);
00388 
00389     _cs = 1;    
00390     _spi.write(0xFF);
00391     return 0;
00392 }
00393 
00394 int SDFileSystem::_write(const char *buffer, int length) {
00395     _cs = 0;
00396     
00397     // indicate start of block
00398     _spi.write(0xFE);
00399     
00400     // write the data
00401     for(int i=0; i<length; i++) {
00402         _spi.write(buffer[i]);
00403     }
00404     
00405     // write the checksum
00406     _spi.write(0xFF); 
00407     _spi.write(0xFF);
00408 
00409     // check the repsonse token
00410     if((_spi.write(0xFF) & 0x1F) != 0x05) {
00411         _cs = 1;
00412         _spi.write(0xFF);        
00413         return 1;
00414     }
00415 
00416     // wait for write to finish
00417     while(_spi.write(0xFF) == 0);
00418 
00419     _cs = 1; 
00420     _spi.write(0xFF);
00421     return 0;
00422 }
00423 
00424 static int ext_bits(char *data, int msb, int lsb) {
00425     int bits = 0;
00426     int size = 1 + msb - lsb; 
00427     for(int i=0; i<size; i++) {
00428         int position = lsb + i;
00429         int byte = 15 - (position >> 3);
00430         int bit = position & 0x7;
00431         int value = (data[byte] >> bit) & 1;
00432         bits |= value << i;
00433     }
00434     return bits;
00435 }
00436 
00437 int SDFileSystem::_sd_sectors() {
00438 
00439     int c_size, c_size_mult, read_bl_len;
00440     int block_len, mult, blocknr, capacity;       
00441     int blocks, hc_c_size;
00442      
00443     // CMD9, Response R2 (R1 byte + 16-byte block read)
00444     if(_cmdx(9, 0) != 0) {
00445         fprintf(stderr, "Didn't get a response from the disk\n");
00446         return 0;
00447     }
00448     
00449     char csd[16];    
00450     if(_read(csd, 16) != 0) {
00451         fprintf(stderr, "Couldn't read csd response from disk\n");
00452         return 0;
00453     }
00454 
00455     // csd_structure : csd[127:126]
00456     // c_size        : csd[73:62]
00457     // c_size_mult   : csd[49:47]
00458     // read_bl_len   : csd[83:80] - the *maximum* read block length
00459    
00460     int csd_structure = ext_bits(csd, 127, 126);
00461     
00462     #ifdef DEBUG 
00463     printf("\n\rCSD_STRUCT = %d\n", csd_structure);
00464     #endif
00465      
00466     switch (csd_structure){
00467      case 0:
00468       cdv = 512;
00469       c_size = ext_bits(csd, 73, 62);
00470       c_size_mult = ext_bits(csd, 49, 47);
00471       read_bl_len = ext_bits(csd, 83, 80);
00472      
00473       block_len = 1 << read_bl_len;
00474       mult = 1 << (c_size_mult + 2);
00475       blocknr = (c_size + 1) * mult;
00476       capacity = blocknr * block_len;
00477       blocks = capacity / 512;
00478       #ifdef DEBUG 
00479       printf("\n\rSDCard\n\rc_size: %.4X \n\rcapacity: %.ld \n\rsectors: %d\n\r", c_size, capacity, blocks);
00480       #endif
00481       break;
00482     
00483      case 1:
00484      {
00485       cdv = 1;
00486       hc_c_size = ext_bits(csd, 63, 48);
00487       int hc_read_bl_len = ext_bits(csd, 83, 80);
00488       blocks = (hc_c_size+1)*1024;
00489       #ifdef DEBUG 
00490       uint64_t hc_capacity = hc_c_size+1;   
00491       printf("\n\rSDHC Card \n\rhc_c_size: %.4X \n\rcapacity: %.lld \n\rsectors: %d\n\r", hc_c_size, hc_capacity*512*1024, blocks);
00492       #endif
00493       break;
00494      }
00495    
00496     default:    
00497        fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n");
00498      return 0;
00499     };
00500  return blocks;
00501 }