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 = 1000000;
00129 }
00130 
00131 #define R1_IDLE_STATE           (1 << 0)
00132 #define R1_ERASE_RESET          (1 << 1)
00133 #define R1_ILLEGAL_COMMAND      (1 << 2)
00134 #define R1_COM_CRC_ERROR        (1 << 3)
00135 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
00136 #define R1_ADDRESS_ERROR        (1 << 5)
00137 #define R1_PARAMETER_ERROR      (1 << 6)
00138 
00139 // Types
00140 //  - v1.x Standard Capacity
00141 //  - v2.x Standard Capacity
00142 //  - v2.x High Capacity
00143 //  - Not recognised as an SD Card
00144 #define SDCARD_FAIL 0
00145 #define SDCARD_V1   1
00146 #define SDCARD_V2   2
00147 #define SDCARD_V2HC 3
00148 
00149 int SDFileSystem::initialise_card() {
00150     _dbg = SD_DBG;
00151     // Set to SCK for initialisation, and clock card with cs = 1
00152     _spi.lock();
00153     _spi.frequency(_init_sck);
00154     _cs = 1;
00155     for (int i = 0; i < 16; i++) {
00156         _spi.write(0xFF);
00157     }
00158     _spi.unlock();
00159 
00160     // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
00161     if (_cmd(0, 0) != R1_IDLE_STATE) {
00162         debug_if(_dbg, "No disk, or could not put SD card in to SPI idle state\n");
00163         return SDCARD_FAIL;
00164     }
00165 
00166     // send CMD8 to determine whther it is ver 2.x
00167     int r = _cmd8();
00168     if (r == R1_IDLE_STATE) {
00169         return initialise_card_v2();
00170     } else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
00171         return initialise_card_v1();
00172     } else {
00173         debug_if(_dbg, "Not in idle state after sending CMD8 (not an SD card?)\n");
00174         return SDCARD_FAIL;
00175     }
00176 }
00177 
00178 int SDFileSystem::initialise_card_v1() {
00179     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00180         _cmd(55, 0);
00181         if (_cmd(41, 0) == 0) {
00182             cdv = 512;
00183             debug_if(_dbg, "\n\rInit: SEDCARD_V1\n\r");
00184             return SDCARD_V1;
00185         }
00186     }
00187 
00188     debug_if(_dbg, "Timeout waiting for v1.x card\n");
00189     return SDCARD_FAIL;
00190 }
00191 
00192 int SDFileSystem::initialise_card_v2() {
00193     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00194         wait_ms(50);
00195         _cmd58();
00196         _cmd(55, 0);
00197         if (_cmd(41, 0x40000000) == 0) {
00198             _cmd58();
00199             debug_if(_dbg, "\n\rInit: SDCARD_V2\n\r");
00200             cdv = 1;
00201             return SDCARD_V2;
00202         }
00203     }
00204 
00205     debug_if(_dbg, "Timeout waiting for v2.x card\n");
00206     return SDCARD_FAIL;
00207 }
00208 
00209 int SDFileSystem::disk_initialize() {
00210     lock();
00211     _is_initialized = initialise_card();
00212     if (_is_initialized == 0) {
00213         debug_if(_dbg, "Fail to initialize card\n");
00214         unlock();
00215         return 1;
00216     }
00217     debug_if(_dbg, "init card = %d\n", _is_initialized);
00218     _sectors = _sd_sectors();
00219 
00220     // Set block length to 512 (CMD16)
00221     if (_cmd(16, 512) != 0) {
00222         debug_if(_dbg, "Set 512-byte block timed out\n");
00223         unlock();
00224         return 1;
00225     }
00226 
00227     // Set SCK for data transfer
00228     _spi.frequency(_transfer_sck);
00229     unlock();
00230     return 0;
00231 }
00232 
00233 int SDFileSystem::disk_write(const uint8_t* buffer, uint32_t block_number, uint32_t count) {
00234     lock();
00235     if (!_is_initialized) {
00236         unlock();
00237         return -1;
00238     }
00239     
00240     for (uint32_t b = block_number; b < block_number + count; b++) {
00241         // set write address for single block (CMD24)
00242         if (_cmd(24, b * cdv) != 0) {
00243             unlock();
00244             return 1;
00245         }
00246         
00247         // send the data block
00248         _write(buffer, 512);
00249         buffer += 512;
00250     }
00251     
00252     unlock();
00253     return 0;
00254 }
00255 
00256 int SDFileSystem::disk_read(uint8_t* buffer, uint32_t block_number, uint32_t count) {
00257     lock();
00258     if (!_is_initialized) {
00259         unlock();
00260         return -1;
00261     }
00262     
00263     for (uint32_t b = block_number; b < block_number + count; b++) {
00264         // set read address for single block (CMD17)
00265         if (_cmd(17, b * cdv) != 0) {
00266             unlock();
00267             return 1;
00268         }
00269         
00270         // receive the data
00271         _read(buffer, 512);
00272         buffer += 512;
00273     }
00274 
00275     unlock();
00276     return 0;
00277 }
00278 
00279 int SDFileSystem::disk_status() {
00280     lock();
00281     // FATFileSystem::disk_status() returns 0 when initialized
00282     int ret = _is_initialized ? 0 : 1;
00283     unlock();
00284     return ret;
00285 }
00286 
00287 int SDFileSystem::disk_sync() { return 0; }
00288 uint32_t SDFileSystem::disk_sectors() {
00289     lock();
00290     uint32_t sectors = _sectors;
00291     unlock();
00292     return sectors;
00293 }
00294 
00295 void SDFileSystem::debug(bool dbg){
00296     _dbg = dbg;
00297 }
00298 
00299 
00300 // PRIVATE FUNCTIONS
00301 int SDFileSystem::_cmd(int cmd, int arg) {
00302     _spi.lock();
00303     _cs = 0;
00304 
00305     // send a command
00306     _spi.write(0x40 | cmd);
00307     _spi.write(arg >> 24);
00308     _spi.write(arg >> 16);
00309     _spi.write(arg >> 8);
00310     _spi.write(arg >> 0);
00311     _spi.write(0x95);
00312 
00313     // wait for the repsonse (response[7] == 0)
00314     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00315         int response = _spi.write(0xFF);
00316         if (!(response & 0x80)) {
00317             _cs = 1;
00318             _spi.write(0xFF);
00319             _spi.unlock();
00320             return response;
00321         }
00322     }
00323     _cs = 1;
00324     _spi.write(0xFF);
00325     _spi.unlock();
00326     return -1; // timeout
00327 }
00328 int SDFileSystem::_cmdx(int cmd, int arg) {
00329     _spi.lock();
00330     _cs = 0;
00331 
00332     // send a command
00333     _spi.write(0x40 | cmd);
00334     _spi.write(arg >> 24);
00335     _spi.write(arg >> 16);
00336     _spi.write(arg >> 8);
00337     _spi.write(arg >> 0);
00338     _spi.write(0x95);
00339 
00340     // wait for the repsonse (response[7] == 0)
00341     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00342         int response = _spi.write(0xFF);
00343         if (!(response & 0x80)) {
00344             _cs = 1;
00345             _spi.unlock();
00346             return response;
00347         }
00348     }
00349     _cs = 1;
00350     _spi.write(0xFF);
00351     _spi.unlock();
00352     return -1; // timeout
00353 }
00354 
00355 
00356 int SDFileSystem::_cmd58() {
00357     _spi.lock();
00358     _cs = 0;
00359     int arg = 0;
00360 
00361     // send a command
00362     _spi.write(0x40 | 58);
00363     _spi.write(arg >> 24);
00364     _spi.write(arg >> 16);
00365     _spi.write(arg >> 8);
00366     _spi.write(arg >> 0);
00367     _spi.write(0x95);
00368 
00369     // wait for the repsonse (response[7] == 0)
00370     for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
00371         int response = _spi.write(0xFF);
00372         if (!(response & 0x80)) {
00373             int ocr = _spi.write(0xFF) << 24;
00374             ocr |= _spi.write(0xFF) << 16;
00375             ocr |= _spi.write(0xFF) << 8;
00376             ocr |= _spi.write(0xFF) << 0;
00377             _cs = 1;
00378             _spi.write(0xFF);
00379             _spi.unlock();
00380             return response;
00381         }
00382     }
00383     _cs = 1;
00384     _spi.write(0xFF);
00385     _spi.unlock();
00386     return -1; // timeout
00387 }
00388 
00389 int SDFileSystem::_cmd8() {
00390     _spi.lock();
00391     _cs = 0;
00392 
00393     // send a command
00394     _spi.write(0x40 | 8); // CMD8
00395     _spi.write(0x00);     // reserved
00396     _spi.write(0x00);     // reserved
00397     _spi.write(0x01);     // 3.3v
00398     _spi.write(0xAA);     // check pattern
00399     _spi.write(0x87);     // crc
00400 
00401     // wait for the repsonse (response[7] == 0)
00402     for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) {
00403         char response[5];
00404         response[0] = _spi.write(0xFF);
00405         if (!(response[0] & 0x80)) {
00406             for (int j = 1; j < 5; j++) {
00407                 response[i] = _spi.write(0xFF);
00408             }
00409             _cs = 1;
00410             _spi.write(0xFF);
00411             _spi.unlock();
00412             return response[0];
00413         }
00414     }
00415     _cs = 1;
00416     _spi.write(0xFF);
00417     _spi.unlock();
00418     return -1; // timeout
00419 }
00420 
00421 int SDFileSystem::_read(uint8_t *buffer, uint32_t length) {
00422     _spi.lock();
00423     _cs = 0;
00424 
00425     // read until start byte (0xFF)
00426     while (_spi.write(0xFF) != 0xFE);
00427 
00428     // read data
00429     for (uint32_t i = 0; i < length; i++) {
00430         buffer[i] = _spi.write(0xFF);
00431     }
00432     _spi.write(0xFF); // checksum
00433     _spi.write(0xFF);
00434 
00435     _cs = 1;
00436     _spi.write(0xFF);
00437     _spi.unlock();
00438     return 0;
00439 }
00440 
00441 int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) {
00442     _spi.lock();
00443     _cs = 0;
00444 
00445     // indicate start of block
00446     _spi.write(0xFE);
00447 
00448     // write the data
00449     for (uint32_t i = 0; i < length; i++) {
00450         _spi.write(buffer[i]);
00451     }
00452 
00453     // write the checksum
00454     _spi.write(0xFF);
00455     _spi.write(0xFF);
00456 
00457     // check the response token
00458     if ((_spi.write(0xFF) & 0x1F) != 0x05) {
00459         _cs = 1;
00460         _spi.write(0xFF);
00461         _spi.unlock();
00462         return 1;
00463     }
00464 
00465     // wait for write to finish
00466     while (_spi.write(0xFF) == 0);
00467 
00468     _cs = 1;
00469     _spi.write(0xFF);
00470     _spi.unlock();
00471     return 0;
00472 }
00473 
00474 static uint32_t ext_bits(unsigned char *data, int msb, int lsb) {
00475     uint32_t bits = 0;
00476     uint32_t size = 1 + msb - lsb;
00477     for (uint32_t i = 0; i < size; i++) {
00478         uint32_t position = lsb + i;
00479         uint32_t byte = 15 - (position >> 3);
00480         uint32_t bit = position & 0x7;
00481         uint32_t value = (data[byte] >> bit) & 1;
00482         bits |= value << i;
00483     }
00484     return bits;
00485 }
00486 
00487 uint32_t SDFileSystem::_sd_sectors() {
00488     uint32_t c_size, c_size_mult, read_bl_len;
00489     uint32_t block_len, mult, blocknr, capacity;
00490     uint32_t hc_c_size;
00491     uint32_t blocks;
00492 
00493     // CMD9, Response R2 (R1 byte + 16-byte block read)
00494     if (_cmdx(9, 0) != 0) {
00495         debug_if(_dbg, "Didn't get a response from the disk\n");
00496         return 0;
00497     }
00498 
00499     uint8_t csd[16];
00500     if (_read(csd, 16) != 0) {
00501         debug_if(_dbg, "Couldn't read csd response from disk\n");
00502         return 0;
00503     }
00504 
00505     // csd_structure : csd[127:126]
00506     // c_size        : csd[73:62]
00507     // c_size_mult   : csd[49:47]
00508     // read_bl_len   : csd[83:80] - the *maximum* read block length
00509 
00510     int csd_structure = ext_bits(csd, 127, 126);
00511 
00512     switch (csd_structure) {
00513         case 0:
00514             cdv = 512;
00515             c_size = ext_bits(csd, 73, 62);
00516             c_size_mult = ext_bits(csd, 49, 47);
00517             read_bl_len = ext_bits(csd, 83, 80);
00518 
00519             block_len = 1 << read_bl_len;
00520             mult = 1 << (c_size_mult + 2);
00521             blocknr = (c_size + 1) * mult;
00522             capacity = blocknr * block_len;
00523             blocks = capacity / 512;
00524             debug_if(_dbg, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks);
00525             break;
00526 
00527         case 1:
00528             cdv = 1;
00529             hc_c_size = ext_bits(csd, 63, 48);
00530             blocks = (hc_c_size+1)*1024;
00531             debug_if(_dbg, "\n\rSDHC Card \n\rhc_c_size: %d\n\rcapacity: %lld \n\rsectors: %lld\n\r", hc_c_size, blocks*512, blocks);
00532             break;
00533 
00534         default:
00535             debug_if(_dbg, "CSD struct unsupported\r\n");
00536             return 0;
00537     };
00538     return blocks;
00539 }