SDFileSystem.cpp

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2012 ARM Limited
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 THE
00020  * SOFTWARE.
00021  */
00022 /* Introduction
00023  * ------------
00024  * SD and MMC cards support a number of interfaces, but common to them all
00025  * is one based on SPI. This is the one I'm implmenting because it means
00026  * it is much more portable even though not so performant, and we already
00027  * have the mbed SPI Interface!
00028  *
00029  * The main reference I'm using is Chapter 7, "SPI Mode" of:
00030  *  http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
00031  *
00032  * SPI Startup
00033  * -----------
00034  * The SD card powers up in SD mode. The SPI interface mode is selected by
00035  * asserting CS low and sending the reset command (CMD0). The card will
00036  * respond with a (R1) response.
00037  *
00038  * CMD8 is optionally sent to determine the voltage range supported, and
00039  * indirectly determine whether it is a version 1.x SD/non-SD card or
00040  * version 2.x. I'll just ignore this for now.
00041  *
00042  * ACMD41 is repeatedly issued to initialise the card, until "in idle"
00043  * (bit 0) of the R1 response goes to '0', indicating it is initialised.
00044  *
00045  * You should also indicate whether the host supports High Capicity cards,
00046  * and check whether the card is high capacity - i'll also ignore this
00047  *
00048  * SPI Protocol
00049  * ------------
00050  * The SD SPI protocol is based on transactions made up of 8-bit words, with
00051  * the host starting every bus transaction by asserting the CS signal low. The
00052  * card always responds to commands, data blocks and errors.
00053  *
00054  * The protocol supports a CRC, but by default it is off (except for the
00055  * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
00056  * I'll leave the CRC off I think!
00057  *
00058  * Standard capacity cards have variable data block sizes, whereas High
00059  * Capacity cards fix the size of data block to 512 bytes. I'll therefore
00060  * just always use the Standard Capacity cards with a block size of 512 bytes.
00061  * This is set with CMD16.
00062  *
00063  * You can read and write single blocks (CMD17, CMD25) or multiple blocks
00064  * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
00065  * the card gets a read command, it responds with a response token, and then
00066  * a data token or an error.
00067  *
00068  * SPI Command Format
00069  * ------------------
00070  * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
00071  *
00072  * +---------------+------------+------------+-----------+----------+--------------+
00073  * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
00074  * +---------------+------------+------------+-----------+----------+--------------+
00075  *
00076  * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
00077  *
00078  * All Application Specific commands shall be preceded with APP_CMD (CMD55).
00079  *
00080  * SPI Response Format
00081  * -------------------
00082  * The main response format (R1) is a status byte (normally zero). Key flags:
00083  *  idle - 1 if the card is in an idle state/initialising
00084  *  cmd  - 1 if an illegal command code was detected
00085  *
00086  *    +-------------------------------------------------+
00087  * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
00088  *    +-------------------------------------------------+
00089  *
00090  * R1b is the same, except it is followed by a busy signal (zeros) until
00091  * the first non-zero byte when it is ready again.
00092  *
00093  * Data Response Token
00094  * -------------------
00095  * Every data block written to the card is acknowledged by a byte
00096  * response token
00097  *
00098  * +----------------------+
00099  * | xxx | 0 | status | 1 |
00100  * +----------------------+
00101  *              010 - OK!
00102  *              101 - CRC Error
00103  *              110 - Write Error
00104  *
00105  * Single Block Read and Write
00106  * ---------------------------
00107  *
00108  * Block transfers have a byte header, followed by the data, followed
00109  * by a 16-bit CRC. In our case, the data will always be 512 bytes.
00110  *
00111  * +------+---------+---------+- -  - -+---------+-----------+----------+
00112  * | 0xFE | data[0] | data[1] |        | data[n] | crc[15:8] | crc[7:0] |
00113  * +------+---------+---------+- -  - -+---------+-----------+----------+
00114  */
00115 #include "SDFileSystem.h"
00116 #include "mbed_debug.h"
00117 
00118 #define SD_COMMAND_TIMEOUT 5000
00119 
00120 #define SD_DBG             0
00121 
00122 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
00123     FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs), _is_initialized(0) {
00124     _cs = 1;
00125 
00126     // Set default to 100kHz for initialisation and 1MHz for data transfer
00127     _init_sck = 100000;
00128     _transfer_sck = 10000000;
00129     
00130 }
00131 
00132 #define R1_IDLE_STATE           (1 << 0)
00133 #define R1_ERASE_RESET          (1 << 1)
00134 #define R1_ILLEGAL_COMMAND      (1 << 2)
00135 #define R1_COM_CRC_ERROR        (1 << 3)
00136 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
00137 #define R1_ADDRESS_ERROR        (1 << 5)
00138 #define R1_PARAMETER_ERROR      (1 << 6)
00139 
00140 // Types
00141 //  - v1.x Standard Capacity
00142 //  - v2.x Standard Capacity
00143 //  - v2.x High Capacity
00144 //  - Not recognised as an SD Card
00145 #define SDCARD_FAIL 0
00146 #define SDCARD_V1   1
00147 #define SDCARD_V2   2
00148 #define SDCARD_V2HC 3
00149 
00150 int SDFileSystem::initialise_card() {
00151     // Set to SCK for initialisation, and clock card with cs = 1
00152     _spi.frequency(_init_sck);
00153     _cs = 1;
00154     for (int i = 0; i < 16; i++) {
00155         _spi.write(0xFF);
00156     }
00157 
00158     // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
00159     if (_cmd(0, 0) != R1_IDLE_STATE) {
00160         debug("No disk, or could not put SD card in to SPI idle state\n");
00161         return SDCARD_FAIL;
00162     }
00163 
00164     // send CMD8 to determine whther it is ver 2.x
00165     int r = _cmd8();
00166     if (r == R1_IDLE_STATE) {
00167         return initialise_card_v2();
00168     } else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
00169         return initialise_card_v1();
00170     } else {
00171         debug("Not in idle state after sending CMD8 (not an SD card?)\n");
00172         return SDCARD_FAIL;
00173     }
00174 }
00175 
00176 int SDFileSystem::initialise_card_v1() {
00177     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00178         _cmd(55, 0);
00179         if (_cmd(41, 0) == 0) {
00180             cdv = 512;
00181             debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r");
00182             return SDCARD_V1;
00183         }
00184     }
00185 
00186     debug("Timeout waiting for v1.x card\n");
00187     return SDCARD_FAIL;
00188 }
00189 
00190 int SDFileSystem::initialise_card_v2() {
00191     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00192         wait_ms(50);
00193         _cmd58();
00194         _cmd(55, 0);
00195         if (_cmd(41, 0x40000000) == 0) {
00196             _cmd58();
00197             debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r");
00198             cdv = 1;
00199             return SDCARD_V2;
00200         }
00201     }
00202 
00203     debug("Timeout waiting for v2.x card\n");
00204     return SDCARD_FAIL;
00205 }
00206 
00207 int SDFileSystem::disk_initialize() {
00208     _is_initialized = initialise_card();
00209     if (_is_initialized == 0) {
00210         debug("Fail to initialize card\n");
00211         return 1;
00212     }
00213     debug_if(SD_DBG, "init card = %d\n", _is_initialized);
00214     _sectors = _sd_sectors();
00215 
00216     // Set block length to 512 (CMD16)
00217     if (_cmd(16, 512) != 0) {
00218         debug("Set 512-byte block timed out\n");
00219         return 1;
00220     }
00221 
00222     // Set SCK for data transfer
00223     _spi.frequency(_transfer_sck);
00224     return 0;
00225 }
00226 
00227 int SDFileSystem::disk_write(const uint8_t* buffer, uint32_t block_number, uint32_t count) {
00228     if (!_is_initialized) {
00229         return -1;
00230     }
00231     
00232     for (uint32_t b = block_number; b < block_number + count; b++) {
00233         // set write address for single block (CMD24)
00234         if (_cmd(24, b * cdv) != 0) {
00235             return 1;
00236         }
00237         
00238         // send the data block
00239         _write(buffer, 512);
00240         buffer += 512;
00241     }
00242     
00243     return 0;
00244 }
00245 
00246 int SDFileSystem::disk_read(uint8_t* buffer, uint32_t block_number, uint32_t count) {
00247     if (!_is_initialized) {
00248         return -1;
00249     }
00250     
00251     for (uint32_t b = block_number; b < block_number + count; b++) {
00252         // set read address for single block (CMD17)
00253         if (_cmd(17, b * cdv) != 0) {
00254             return 1;
00255         }
00256         
00257         // receive the data
00258         _read(buffer, 512);
00259         buffer += 512;
00260     }
00261 
00262     return 0;
00263 }
00264 
00265 int SDFileSystem::disk_status() {
00266     // FATFileSystem::disk_status() returns 0 when initialized
00267     if (_is_initialized) {
00268         return 0;
00269     } else {
00270         return 1;
00271     }
00272 }
00273 
00274 int SDFileSystem::disk_sync() { return 0; }
00275 uint32_t SDFileSystem::disk_sectors() { return _sectors; }
00276 
00277 
00278 // PRIVATE FUNCTIONS
00279 int SDFileSystem::_cmd(int cmd, int arg) {
00280     _cs = 0;
00281 
00282     // send a command
00283     _spi.write(0x40 | cmd);
00284     _spi.write(arg >> 24);
00285     _spi.write(arg >> 16);
00286     _spi.write(arg >> 8);
00287     _spi.write(arg >> 0);
00288     _spi.write(0x95);
00289 
00290     // wait for the repsonse (response[7] == 0)
00291     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00292         int response = _spi.write(0xFF);
00293         if (!(response & 0x80)) {
00294             _cs = 1;
00295             _spi.write(0xFF);
00296             return response;
00297         }
00298     }
00299     _cs = 1;
00300     _spi.write(0xFF);
00301     return -1; // timeout
00302 }
00303 int SDFileSystem::_cmdx(int cmd, int arg) {
00304     _cs = 0;
00305 
00306     // send a command
00307     _spi.write(0x40 | cmd);
00308     _spi.write(arg >> 24);
00309     _spi.write(arg >> 16);
00310     _spi.write(arg >> 8);
00311     _spi.write(arg >> 0);
00312     _spi.write(0x95);
00313 
00314     // wait for the repsonse (response[7] == 0)
00315     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00316         int response = _spi.write(0xFF);
00317         if (!(response & 0x80)) {
00318             return response;
00319         }
00320     }
00321     _cs = 1;
00322     _spi.write(0xFF);
00323     return -1; // timeout
00324 }
00325 
00326 
00327 int SDFileSystem::_cmd58() {
00328     _cs = 0;
00329     int arg = 0;
00330 
00331     // send a command
00332     _spi.write(0x40 | 58);
00333     _spi.write(arg >> 24);
00334     _spi.write(arg >> 16);
00335     _spi.write(arg >> 8);
00336     _spi.write(arg >> 0);
00337     _spi.write(0x95);
00338 
00339     // wait for the repsonse (response[7] == 0)
00340     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00341         int response = _spi.write(0xFF);
00342         if (!(response & 0x80)) {
00343             int ocr = _spi.write(0xFF) << 24;
00344             ocr |= _spi.write(0xFF) << 16;
00345             ocr |= _spi.write(0xFF) << 8;
00346             ocr |= _spi.write(0xFF) << 0;
00347             _cs = 1;
00348             _spi.write(0xFF);
00349             return response;
00350         }
00351     }
00352     _cs = 1;
00353     _spi.write(0xFF);
00354     return -1; // timeout
00355 }
00356 
00357 int SDFileSystem::_cmd8() {
00358     _cs = 0;
00359 
00360     // send a command
00361     _spi.write(0x40 | 8); // CMD8
00362     _spi.write(0x00);     // reserved
00363     _spi.write(0x00);     // reserved
00364     _spi.write(0x01);     // 3.3v
00365     _spi.write(0xAA);     // check pattern
00366     _spi.write(0x87);     // crc
00367 
00368     // wait for the repsonse (response[7] == 0)
00369     for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) {
00370         char response[5];
00371         response[0] = _spi.write(0xFF);
00372         if (!(response[0] & 0x80)) {
00373             for (int j = 1; j < 5; j++) {
00374                 response[i] = _spi.write(0xFF);
00375             }
00376             _cs = 1;
00377             _spi.write(0xFF);
00378             return response[0];
00379         }
00380     }
00381     _cs = 1;
00382     _spi.write(0xFF);
00383     return -1; // timeout
00384 }
00385 
00386 int SDFileSystem::_read(uint8_t *buffer, uint32_t length) {
00387     _cs = 0;
00388 
00389     // read until start byte (0xFF)
00390     while (_spi.write(0xFF) != 0xFE);
00391 
00392     // read data
00393     for (uint32_t i = 0; i < length; i++) {
00394         buffer[i] = _spi.write(0xFF);
00395     }
00396     _spi.write(0xFF); // checksum
00397     _spi.write(0xFF);
00398 
00399     _cs = 1;
00400     _spi.write(0xFF);
00401     return 0;
00402 }
00403 
00404 int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) {
00405     _cs = 0;
00406 
00407     // indicate start of block
00408     _spi.write(0xFE);
00409 
00410     // write the data
00411     for (uint32_t i = 0; i < length; i++) {
00412         _spi.write(buffer[i]);
00413     }
00414 
00415     // write the checksum
00416     _spi.write(0xFF);
00417     _spi.write(0xFF);
00418 
00419     // check the response token
00420     if ((_spi.write(0xFF) & 0x1F) != 0x05) {
00421         _cs = 1;
00422         _spi.write(0xFF);
00423         return 1;
00424     }
00425 
00426     // wait for write to finish
00427     while (_spi.write(0xFF) == 0);
00428 
00429     _cs = 1;
00430     _spi.write(0xFF);
00431     return 0;
00432 }
00433 
00434 static uint32_t ext_bits(unsigned char *data, int msb, int lsb) {
00435     uint32_t bits = 0;
00436     uint32_t size = 1 + msb - lsb;
00437     for (uint32_t i = 0; i < size; i++) {
00438         uint32_t position = lsb + i;
00439         uint32_t byte = 15 - (position >> 3);
00440         uint32_t bit = position & 0x7;
00441         uint32_t value = (data[byte] >> bit) & 1;
00442         bits |= value << i;
00443     }
00444     return bits;
00445 }
00446 
00447 uint32_t SDFileSystem::_sd_sectors() {
00448     uint32_t c_size, c_size_mult, read_bl_len;
00449     uint32_t block_len, mult, blocknr, capacity;
00450     uint32_t hc_c_size;
00451     uint32_t blocks;
00452 
00453     // CMD9, Response R2 (R1 byte + 16-byte block read)
00454     if (_cmdx(9, 0) != 0) {
00455         debug("Didn't get a response from the disk\n");
00456         return 0;
00457     }
00458 
00459     uint8_t csd[16];
00460     if (_read(csd, 16) != 0) {
00461         debug("Couldn't read csd response from disk\n");
00462         return 0;
00463     }
00464 
00465     // csd_structure : csd[127:126]
00466     // c_size        : csd[73:62]
00467     // c_size_mult   : csd[49:47]
00468     // read_bl_len   : csd[83:80] - the *maximum* read block length
00469 
00470     int csd_structure = ext_bits(csd, 127, 126);
00471 
00472     switch (csd_structure) {
00473         case 0:
00474             cdv = 512;
00475             c_size = ext_bits(csd, 73, 62);
00476             c_size_mult = ext_bits(csd, 49, 47);
00477             read_bl_len = ext_bits(csd, 83, 80);
00478 
00479             block_len = 1 << read_bl_len;
00480             mult = 1 << (c_size_mult + 2);
00481             blocknr = (c_size + 1) * mult;
00482             capacity = blocknr * block_len;
00483             blocks = capacity / 512;
00484             debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks);
00485             break;
00486 
00487         case 1:
00488             cdv = 1;
00489             hc_c_size = ext_bits(csd, 63, 48);
00490             blocks = (hc_c_size+1)*1024;
00491             debug_if(SD_DBG, "\n\rSDHC Card \n\rhc_c_size: %d\n\rcapacity: %lld \n\rsectors: %lld\n\r", hc_c_size, blocks*512, blocks);
00492             break;
00493 
00494         default:
00495             debug("CSD struct unsupported\r\n");
00496             return 0;
00497     };
00498     return blocks;
00499 }