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