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 #include "SDHCFileSystem.h"
00125 
00126 #define DEBUG
00127 #define SD_COMMAND_TIMEOUT 5000
00128 
00129 
00130 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
00131   FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
00132       _cs = 1; 
00133 }
00134 
00135 #define R1_IDLE_STATE           (1 << 0)
00136 #define R1_ERASE_RESET          (1 << 1)
00137 #define R1_ILLEGAL_COMMAND      (1 << 2)
00138 #define R1_COM_CRC_ERROR        (1 << 3)
00139 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
00140 #define R1_ADDRESS_ERROR        (1 << 5)
00141 #define R1_PARAMETER_ERROR      (1 << 6)
00142 
00143 // Types
00144 //  - v1.x Standard Capacity
00145 //  - v2.x Standard Capacity
00146 //  - v2.x High Capacity
00147 //  - Not recognised as an SD Card
00148 
00149 #define SDCARD_FAIL 0
00150 #define SDCARD_V1   1
00151 #define SDCARD_V2   2
00152 #define SDCARD_V2HC 3
00153 
00154 int SDFileSystem::initialise_card() {
00155     // Set to 100kHz for initialisation, and clock card with cs = 1
00156     _spi.frequency(100000); 
00157     _cs = 1;
00158     for(int i=0; i<16; i++) {   
00159         _spi.write(0xFF);
00160     }
00161 
00162     // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
00163     if(_cmd(0, 0) != R1_IDLE_STATE) { 
00164         fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n");
00165         return SDCARD_FAIL;
00166     }
00167 
00168     // send CMD8 to determine whther it is ver 2.x
00169     int r = _cmd8();
00170     if(r == R1_IDLE_STATE) {
00171         return initialise_card_v2();
00172     } else if(r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
00173         return initialise_card_v1();
00174     } else {
00175         fprintf(stderr, "Not in idle state after sending CMD8 (not an SD card?)\n");
00176         return SDCARD_FAIL;
00177     }
00178 }
00179 
00180 int SDFileSystem::initialise_card_v1() {
00181     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00182         _cmd(55, 0); 
00183         if(_cmd(41, 0) == 0) { 
00184             cdv = 512;
00185             #ifdef DEBUG 
00186             printf("\n\rInit: SEDCARD_V1\n\r");
00187             #endif
00188             return SDCARD_V1;
00189         }
00190     }
00191 
00192     fprintf(stderr, "Timeout waiting for v1.x card\n");
00193     return SDCARD_FAIL;
00194 }
00195 
00196 int SDFileSystem::initialise_card_v2() {
00197     
00198     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00199         wait_ms(50);
00200         _cmd58();
00201         _cmd(55, 0); 
00202         if(_cmd(41, 0x40000000) == 0) { 
00203             _cmd58();
00204             #ifdef DEBUG
00205             printf("\n\rInit: SDCARD_V2\n\r");
00206             #endif
00207             cdv = 1;
00208             return SDCARD_V2;
00209         }
00210     }
00211 
00212     fprintf(stderr, "Timeout waiting for v2.x card\n");
00213     return SDCARD_FAIL;
00214 }
00215 
00216 int SDFileSystem::disk_initialize() {
00217 
00218     int i = initialise_card();
00219     #ifdef DEBUG 
00220     printf("init card = %d\n", i);
00221     #endif
00222     _sectors = _sd_sectors();
00223 
00224     // Set block length to 512 (CMD16)
00225     if(_cmd(16, 512) != 0) {
00226         fprintf(stderr, "Set 512-byte block timed out\n");
00227         return 1;
00228     }
00229         
00230     _spi.frequency(1000000); // Set to 1MHz for data transfer
00231     return 0;
00232 }
00233 
00234 int SDFileSystem::disk_write(const char *buffer, int block_number) {
00235     // set write address for single block (CMD24)
00236     if(_cmd(24, block_number * cdv) != 0) {
00237         return 1;
00238     }
00239 
00240     // send the data block
00241     _write(buffer, 512);    
00242     return 0;    
00243 }
00244 
00245 int SDFileSystem::disk_read(char *buffer, int block_number) {        
00246     // set read address for single block (CMD17)
00247     if(_cmd(17, block_number * cdv) != 0) {
00248         return 1;
00249     }
00250     
00251     // receive the data
00252     _read(buffer, 512);
00253     return 0;
00254 }
00255 
00256 int SDFileSystem::disk_status() { return 0; }
00257 int SDFileSystem::disk_sync() { return 0; }
00258 int SDFileSystem::disk_sectors() { return _sectors; }
00259 
00260 // PRIVATE FUNCTIONS
00261 
00262 int SDFileSystem::_cmd(int cmd, int arg) {
00263     _cs = 0; 
00264 
00265     // send a command
00266     _spi.write(0x40 | cmd);
00267     _spi.write(arg >> 24);
00268     _spi.write(arg >> 16);
00269     _spi.write(arg >> 8);
00270     _spi.write(arg >> 0);
00271     _spi.write(0x95);
00272 
00273     // wait for the repsonse (response[7] == 0)
00274     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00275         int response = _spi.write(0xFF);
00276         if(!(response & 0x80)) {
00277             _cs = 1;
00278             _spi.write(0xFF);
00279             return response;
00280         }
00281     }
00282     _cs = 1;
00283     _spi.write(0xFF);
00284     return -1; // timeout
00285 }
00286 int SDFileSystem::_cmdx(int cmd, int arg) {
00287     _cs = 0; 
00288 
00289     // send a command
00290     _spi.write(0x40 | cmd);
00291     _spi.write(arg >> 24);
00292     _spi.write(arg >> 16);
00293     _spi.write(arg >> 8);
00294     _spi.write(arg >> 0);
00295     _spi.write(0x95);
00296 
00297     // wait for the repsonse (response[7] == 0)
00298     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00299         int response = _spi.write(0xFF);
00300         if(!(response & 0x80)) {
00301             return response;
00302         }
00303     }
00304     _cs = 1;
00305     _spi.write(0xFF);
00306     return -1; // timeout
00307 }
00308 
00309 
00310 int SDFileSystem::_cmd58() {
00311     _cs = 0; 
00312     int arg = 0;
00313     
00314     // send a command
00315     _spi.write(0x40 | 58);
00316     _spi.write(arg >> 24);
00317     _spi.write(arg >> 16);
00318     _spi.write(arg >> 8);
00319     _spi.write(arg >> 0);
00320     _spi.write(0x95);
00321 
00322     // wait for the repsonse (response[7] == 0)
00323     for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
00324         int response = _spi.write(0xFF);
00325         if(!(response & 0x80)) {
00326             int ocr = _spi.write(0xFF) << 24;
00327             ocr |= _spi.write(0xFF) << 16;
00328             ocr |= _spi.write(0xFF) << 8;
00329             ocr |= _spi.write(0xFF) << 0;
00330 //            printf("OCR = 0x%08X\n", ocr);
00331             _cs = 1;
00332             _spi.write(0xFF);
00333             return response;
00334         }
00335     }
00336     _cs = 1;
00337     _spi.write(0xFF);
00338     return -1; // timeout
00339 }
00340 
00341 int SDFileSystem::_cmd8() {
00342     _cs = 0; 
00343     
00344     // send a command
00345     _spi.write(0x40 | 8); // CMD8
00346     _spi.write(0x00);     // reserved
00347     _spi.write(0x00);     // reserved
00348     _spi.write(0x01);     // 3.3v
00349     _spi.write(0xAA);     // check pattern
00350     _spi.write(0x87);     // crc
00351 
00352     // wait for the repsonse (response[7] == 0)
00353     for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
00354         char response[5];
00355         response[0] = _spi.write(0xFF);
00356         if(!(response[0] & 0x80)) {
00357                 for(int j=1; j<5; j++) {
00358                     response[i] = _spi.write(0xFF);
00359                 }
00360                 _cs = 1;
00361                 _spi.write(0xFF);
00362                 return response[0];
00363         }
00364     }
00365     _cs = 1;
00366     _spi.write(0xFF);
00367     return -1; // timeout
00368 }
00369 
00370 int SDFileSystem::_read(char *buffer, int length) {
00371     _cs = 0;
00372 
00373     // read until start byte (0xFF)
00374     while(_spi.write(0xFF) != 0xFE);
00375 
00376     // read data
00377     for(int i=0; i<length; i++) {
00378         buffer[i] = _spi.write(0xFF);
00379     }
00380     _spi.write(0xFF); // checksum
00381     _spi.write(0xFF);
00382 
00383     _cs = 1;    
00384     _spi.write(0xFF);
00385     return 0;
00386 }
00387 
00388 int SDFileSystem::_write(const char *buffer, int length) {
00389     _cs = 0;
00390     
00391     // indicate start of block
00392     _spi.write(0xFE);
00393     
00394     // write the data
00395     for(int i=0; i<length; i++) {
00396         _spi.write(buffer[i]);
00397     }
00398     
00399     // write the checksum
00400     _spi.write(0xFF); 
00401     _spi.write(0xFF);
00402 
00403     // check the repsonse token
00404     if((_spi.write(0xFF) & 0x1F) != 0x05) {
00405         _cs = 1;
00406         _spi.write(0xFF);        
00407         return 1;
00408     }
00409 
00410     // wait for write to finish
00411     while(_spi.write(0xFF) == 0);
00412 
00413     _cs = 1; 
00414     _spi.write(0xFF);
00415     return 0;
00416 }
00417 
00418 static int ext_bits(char *data, int msb, int lsb) {
00419     int bits = 0;
00420     int size = 1 + msb - lsb; 
00421     for(int i=0; i<size; i++) {
00422         int position = lsb + i;
00423         int byte = 15 - (position >> 3);
00424         int bit = position & 0x7;
00425         int value = (data[byte] >> bit) & 1;
00426         bits |= value << i;
00427     }
00428     return bits;
00429 }
00430 
00431 int SDFileSystem::_sd_sectors() {
00432 
00433     int c_size, c_size_mult, read_bl_len;
00434     int block_len, mult, blocknr, capacity;       
00435     int blocks, hc_c_size;
00436     uint64_t hc_capacity;
00437      
00438     // CMD9, Response R2 (R1 byte + 16-byte block read)
00439     if(_cmdx(9, 0) != 0) {
00440         fprintf(stderr, "Didn't get a response from the disk\n");
00441         return 0;
00442     }
00443     
00444     char csd[16];    
00445     if(_read(csd, 16) != 0) {
00446         fprintf(stderr, "Couldn't read csd response from disk\n");
00447         return 0;
00448     }
00449 
00450     // csd_structure : csd[127:126]
00451     // c_size        : csd[73:62]
00452     // c_size_mult   : csd[49:47]
00453     // read_bl_len   : csd[83:80] - the *maximum* read block length
00454    
00455     int csd_structure = ext_bits(csd, 127, 126);
00456     
00457     #ifdef DEBUG 
00458     printf("\n\rCSD_STRUCT = %d\n", csd_structure);
00459     #endif
00460      
00461     switch (csd_structure){
00462      case 0:
00463       cdv = 512;
00464       c_size = ext_bits(csd, 73, 62);
00465       c_size_mult = ext_bits(csd, 49, 47);
00466       read_bl_len = ext_bits(csd, 83, 80);
00467      
00468       block_len = 1 << read_bl_len;
00469       mult = 1 << (c_size_mult + 2);
00470       blocknr = (c_size + 1) * mult;
00471       capacity = blocknr * block_len;
00472       blocks = capacity / 512;
00473       #ifdef DEBUG 
00474       printf("\n\rSDCard\n\rc_size: %.4X \n\rcapacity: %.ld \n\rsectors: %d\n\r", c_size, capacity, blocks);
00475       #endif
00476       break;
00477     
00478      case 1:
00479       cdv = 1;
00480       hc_c_size = ext_bits(csd, 63, 48);
00481       int hc_read_bl_len = ext_bits(csd, 83, 80);
00482       hc_capacity = hc_c_size+1;   
00483       blocks = (hc_c_size+1)*1024;
00484       #ifdef DEBUG 
00485       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);
00486       #endif
00487       break;
00488    
00489     default:    
00490        fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n");
00491      return 0;
00492  //    break;
00493     };
00494  return blocks;
00495 }