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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 = 25000000; 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.frequency(_init_sck); 00152 _cs = 1; 00153 for (int i = 0; i < 16; i++) { 00154 _spi.write(0xFF); 00155 } 00156 00157 // send CMD0, should return with all zeros except IDLE STATE set (bit 0) 00158 if (_cmd(0, 0) != R1_IDLE_STATE) { 00159 debug("No disk, or could not put SD card in to SPI idle state\n"); 00160 return SDCARD_FAIL; 00161 } 00162 00163 // send CMD8 to determine whther it is ver 2.x 00164 int r = _cmd8(); 00165 if (r == R1_IDLE_STATE) { 00166 return initialise_card_v2(); 00167 } else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) { 00168 return initialise_card_v1(); 00169 } else { 00170 debug("Not in idle state after sending CMD8 (not an SD card?)\n"); 00171 return SDCARD_FAIL; 00172 } 00173 } 00174 00175 int SDFileSystem::initialise_card_v1() { 00176 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00177 _cmd(55, 0); 00178 if (_cmd(41, 0) == 0) { 00179 cdv = 512; 00180 debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r"); 00181 return SDCARD_V1; 00182 } 00183 } 00184 00185 debug("Timeout waiting for v1.x card\n"); 00186 return SDCARD_FAIL; 00187 } 00188 00189 int SDFileSystem::initialise_card_v2() { 00190 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00191 wait_ms(50); 00192 _cmd58(); 00193 _cmd(55, 0); 00194 if (_cmd(41, 0x40000000) == 0) { 00195 _cmd58(); 00196 debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r"); 00197 cdv = 1; 00198 return SDCARD_V2; 00199 } 00200 } 00201 00202 debug("Timeout waiting for v2.x card\n"); 00203 return SDCARD_FAIL; 00204 } 00205 00206 int SDFileSystem::disk_initialize() { 00207 _is_initialized = initialise_card(); 00208 if (_is_initialized == 0) { 00209 debug("Fail to initialize card\n"); 00210 return 1; 00211 } 00212 debug_if(SD_DBG, "init card = %d\n", _is_initialized); 00213 _sectors = _sd_sectors(); 00214 00215 // Set block length to 512 (CMD16) 00216 if (_cmd(16, 512) != 0) { 00217 debug("Set 512-byte block timed out\n"); 00218 return 1; 00219 } 00220 00221 // Set SCK for data transfer 00222 _spi.frequency(_transfer_sck); 00223 return 0; 00224 } 00225 00226 int SDFileSystem::disk_write(const uint8_t* buffer, uint32_t block_number, uint32_t count) { 00227 if (!_is_initialized) { 00228 return -1; 00229 } 00230 00231 for (uint32_t b = block_number; b < block_number + count; b++) { 00232 // set write address for single block (CMD24) 00233 if (_cmd(24, b * cdv) != 0) { 00234 return 1; 00235 } 00236 00237 // send the data block 00238 _write(buffer, 512); 00239 buffer += 512; 00240 } 00241 00242 return 0; 00243 } 00244 00245 int SDFileSystem::disk_read(uint8_t* buffer, uint32_t block_number, uint32_t count) { 00246 if (!_is_initialized) { 00247 return -1; 00248 } 00249 00250 if (count == 1) { 00251 // set read address for single block (CMD17) 00252 if (_cmd(17, block_number * cdv) != 0) { 00253 return 1; 00254 } 00255 00256 // receive the data 00257 _read(buffer, 512); 00258 buffer += 512; 00259 00260 return 0; 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(18, b * cdv) != 0) { 00266 return 1; 00267 } 00268 00269 // receive the data 00270 do { 00271 _read(buffer, 512); 00272 buffer += 512; 00273 } while (--count); 00274 _cmd(12, 0); 00275 } 00276 00277 return 0; 00278 } 00279 00280 int SDFileSystem::disk_status() { 00281 // FATFileSystem::disk_status() returns 0 when initialized 00282 if (_is_initialized) { 00283 return 0; 00284 } else { 00285 return 1; 00286 } 00287 } 00288 00289 int SDFileSystem::disk_sync() { return 0; } 00290 uint32_t SDFileSystem::disk_sectors() { return _sectors; } 00291 00292 00293 // PRIVATE FUNCTIONS 00294 int SDFileSystem::_cmd(int cmd, int arg) { 00295 _cs = 0; 00296 00297 // send a command 00298 _spi.write(0x40 | cmd); 00299 _spi.write(arg >> 24); 00300 _spi.write(arg >> 16); 00301 _spi.write(arg >> 8); 00302 _spi.write(arg >> 0); 00303 _spi.write(0x95); 00304 00305 // wait for the repsonse (response[7] == 0) 00306 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00307 int response = _spi.write(0xFF); 00308 if (!(response & 0x80)) { 00309 _cs = 1; 00310 _spi.write(0xFF); 00311 return response; 00312 } 00313 } 00314 _cs = 1; 00315 _spi.write(0xFF); 00316 return -1; // timeout 00317 } 00318 int SDFileSystem::_cmdx(int cmd, int arg) { 00319 _cs = 0; 00320 00321 // send a command 00322 _spi.write(0x40 | cmd); 00323 _spi.write(arg >> 24); 00324 _spi.write(arg >> 16); 00325 _spi.write(arg >> 8); 00326 _spi.write(arg >> 0); 00327 _spi.write(0x95); 00328 00329 // wait for the repsonse (response[7] == 0) 00330 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00331 int response = _spi.write(0xFF); 00332 if (!(response & 0x80)) { 00333 return response; 00334 } 00335 } 00336 _cs = 1; 00337 _spi.write(0xFF); 00338 return -1; // timeout 00339 } 00340 00341 00342 int SDFileSystem::_cmd58() { 00343 _cs = 0; 00344 int arg = 0; 00345 00346 // send a command 00347 _spi.write(0x40 | 58); 00348 _spi.write(arg >> 24); 00349 _spi.write(arg >> 16); 00350 _spi.write(arg >> 8); 00351 _spi.write(arg >> 0); 00352 _spi.write(0x95); 00353 00354 // wait for the repsonse (response[7] == 0) 00355 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00356 int response = _spi.write(0xFF); 00357 if (!(response & 0x80)) { 00358 int ocr = _spi.write(0xFF) << 24; 00359 ocr |= _spi.write(0xFF) << 16; 00360 ocr |= _spi.write(0xFF) << 8; 00361 ocr |= _spi.write(0xFF) << 0; 00362 _cs = 1; 00363 _spi.write(0xFF); 00364 return response; 00365 } 00366 } 00367 _cs = 1; 00368 _spi.write(0xFF); 00369 return -1; // timeout 00370 } 00371 00372 int SDFileSystem::_cmd8() { 00373 _cs = 0; 00374 00375 // send a command 00376 _spi.write(0x40 | 8); // CMD8 00377 _spi.write(0x00); // reserved 00378 _spi.write(0x00); // reserved 00379 _spi.write(0x01); // 3.3v 00380 _spi.write(0xAA); // check pattern 00381 _spi.write(0x87); // crc 00382 00383 // wait for the repsonse (response[7] == 0) 00384 for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) { 00385 char response[5]; 00386 response[0] = _spi.write(0xFF); 00387 if (!(response[0] & 0x80)) { 00388 for (int j = 1; j < 5; j++) { 00389 response[i] = _spi.write(0xFF); 00390 } 00391 _cs = 1; 00392 _spi.write(0xFF); 00393 return response[0]; 00394 } 00395 } 00396 _cs = 1; 00397 _spi.write(0xFF); 00398 return -1; // timeout 00399 } 00400 00401 int SDFileSystem::_read(uint8_t *buffer, uint32_t length) { 00402 _cs = 0; 00403 00404 // read until start byte (0xFF) 00405 while (_spi.write(0xFF) != 0xFE); 00406 00407 // read data 00408 for (uint32_t i = 0; i < length; i++) { 00409 buffer[i] = _spi.write(0xFF); 00410 } 00411 _spi.write(0xFF); // checksum 00412 _spi.write(0xFF); 00413 00414 _cs = 1; 00415 _spi.write(0xFF); 00416 return 0; 00417 } 00418 00419 int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) { 00420 _cs = 0; 00421 00422 // indicate start of block 00423 _spi.write(0xFE); 00424 00425 // write the data 00426 for (uint32_t i = 0; i < length; i++) { 00427 _spi.write(buffer[i]); 00428 } 00429 00430 // write the checksum 00431 _spi.write(0xFF); 00432 _spi.write(0xFF); 00433 00434 // check the response token 00435 if ((_spi.write(0xFF) & 0x1F) != 0x05) { 00436 _cs = 1; 00437 _spi.write(0xFF); 00438 return 1; 00439 } 00440 00441 // wait for write to finish 00442 while (_spi.write(0xFF) == 0); 00443 00444 _cs = 1; 00445 _spi.write(0xFF); 00446 return 0; 00447 } 00448 00449 static uint32_t ext_bits(unsigned char *data, int msb, int lsb) { 00450 uint32_t bits = 0; 00451 uint32_t size = 1 + msb - lsb; 00452 for (uint32_t i = 0; i < size; i++) { 00453 uint32_t position = lsb + i; 00454 uint32_t byte = 15 - (position >> 3); 00455 uint32_t bit = position & 0x7; 00456 uint32_t value = (data[byte] >> bit) & 1; 00457 bits |= value << i; 00458 } 00459 return bits; 00460 } 00461 00462 uint32_t SDFileSystem::_sd_sectors() { 00463 uint32_t c_size, c_size_mult, read_bl_len; 00464 uint32_t block_len, mult, blocknr, capacity; 00465 uint32_t hc_c_size; 00466 uint32_t blocks; 00467 00468 // CMD9, Response R2 (R1 byte + 16-byte block read) 00469 if (_cmdx(9, 0) != 0) { 00470 debug("Didn't get a response from the disk\n"); 00471 return 0; 00472 } 00473 00474 uint8_t csd[16]; 00475 if (_read(csd, 16) != 0) { 00476 debug("Couldn't read csd response from disk\n"); 00477 return 0; 00478 } 00479 00480 // csd_structure : csd[127:126] 00481 // c_size : csd[73:62] 00482 // c_size_mult : csd[49:47] 00483 // read_bl_len : csd[83:80] - the *maximum* read block length 00484 00485 int csd_structure = ext_bits(csd, 127, 126); 00486 00487 switch (csd_structure) { 00488 case 0: 00489 cdv = 512; 00490 c_size = ext_bits(csd, 73, 62); 00491 c_size_mult = ext_bits(csd, 49, 47); 00492 read_bl_len = ext_bits(csd, 83, 80); 00493 00494 block_len = 1 << read_bl_len; 00495 mult = 1 << (c_size_mult + 2); 00496 blocknr = (c_size + 1) * mult; 00497 capacity = blocknr * block_len; 00498 blocks = capacity / 512; 00499 debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks); 00500 break; 00501 00502 case 1: 00503 cdv = 1; 00504 hc_c_size = ext_bits(csd, 63, 48); 00505 blocks = (hc_c_size+1)*1024; 00506 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); 00507 break; 00508 00509 default: 00510 debug("CSD struct unsupported\r\n"); 00511 return 0; 00512 }; 00513 return blocks; 00514 }
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