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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) { 00124 _cs = 1; 00125 } 00126 00127 #define R1_IDLE_STATE (1 << 0) 00128 #define R1_ERASE_RESET (1 << 1) 00129 #define R1_ILLEGAL_COMMAND (1 << 2) 00130 #define R1_COM_CRC_ERROR (1 << 3) 00131 #define R1_ERASE_SEQUENCE_ERROR (1 << 4) 00132 #define R1_ADDRESS_ERROR (1 << 5) 00133 #define R1_PARAMETER_ERROR (1 << 6) 00134 00135 // Types 00136 // - v1.x Standard Capacity 00137 // - v2.x Standard Capacity 00138 // - v2.x High Capacity 00139 // - Not recognised as an SD Card 00140 #define SDCARD_FAIL 0 00141 #define SDCARD_V1 1 00142 #define SDCARD_V2 2 00143 #define SDCARD_V2HC 3 00144 00145 int SDFileSystem::initialise_card() { 00146 // Set to 100kHz for initialisation, and clock card with cs = 1 00147 _spi.frequency(20000000); 00148 _cs = 1; 00149 for (int i = 0; i < 16; i++) { 00150 _spi.write(0xFF); 00151 } 00152 00153 // send CMD0, should return with all zeros except IDLE STATE set (bit 0) 00154 if (_cmd(0, 0) != R1_IDLE_STATE) { 00155 debug("No disk, or could not put SD card in to SPI idle state\n"); 00156 return SDCARD_FAIL; 00157 } 00158 00159 // send CMD8 to determine whther it is ver 2.x 00160 int r = _cmd8(); 00161 if (r == R1_IDLE_STATE) { 00162 return initialise_card_v2(); 00163 } else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) { 00164 return initialise_card_v1(); 00165 } else { 00166 debug("Not in idle state after sending CMD8 (not an SD card?)\n"); 00167 return SDCARD_FAIL; 00168 } 00169 } 00170 00171 int SDFileSystem::initialise_card_v1() { 00172 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00173 _cmd(55, 0); 00174 if (_cmd(41, 0) == 0) { 00175 cdv = 512; 00176 debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r"); 00177 return SDCARD_V1; 00178 } 00179 } 00180 00181 debug("Timeout waiting for v1.x card\n"); 00182 return SDCARD_FAIL; 00183 } 00184 00185 int SDFileSystem::initialise_card_v2() { 00186 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00187 wait_ms(50); 00188 _cmd58(); 00189 _cmd(55, 0); 00190 if (_cmd(41, 0x40000000) == 0) { 00191 _cmd58(); 00192 debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r"); 00193 cdv = 1; 00194 return SDCARD_V2; 00195 } 00196 } 00197 00198 debug("Timeout waiting for v2.x card\n"); 00199 return SDCARD_FAIL; 00200 } 00201 00202 int SDFileSystem::disk_initialize() { 00203 int i = initialise_card(); 00204 debug_if(SD_DBG, "init card = %d\n", i); 00205 _sectors = _sd_sectors(); 00206 00207 // Set block length to 512 (CMD16) 00208 if (_cmd(16, 512) != 0) { 00209 debug("Set 512-byte block timed out\n"); 00210 return 1; 00211 } 00212 00213 _spi.frequency(20000000); // Set to 1MHz for data transfer 00214 return 0; 00215 } 00216 00217 int SDFileSystem::disk_write(const uint8_t *buffer, uint64_t block_number) { 00218 // set write address for single block (CMD24) 00219 if (_cmd(24, block_number * cdv) != 0) { 00220 return 1; 00221 } 00222 00223 // send the data block 00224 _write(buffer, 512); 00225 return 0; 00226 } 00227 00228 int SDFileSystem::disk_read(uint8_t *buffer, uint64_t block_number) { 00229 // set read address for single block (CMD17) 00230 if (_cmd(17, block_number * cdv) != 0) { 00231 return 1; 00232 } 00233 00234 // receive the data 00235 _read(buffer, 512); 00236 return 0; 00237 } 00238 00239 int SDFileSystem::disk_status() { return 0; } 00240 int SDFileSystem::disk_sync() { return 0; } 00241 uint64_t SDFileSystem::disk_sectors() { return _sectors; } 00242 00243 00244 // PRIVATE FUNCTIONS 00245 int SDFileSystem::_cmd(int cmd, int arg) { 00246 _cs = 0; 00247 00248 // send a command 00249 _spi.write(0x40 | cmd); 00250 _spi.write(arg >> 24); 00251 _spi.write(arg >> 16); 00252 _spi.write(arg >> 8); 00253 _spi.write(arg >> 0); 00254 _spi.write(0x95); 00255 00256 // wait for the repsonse (response[7] == 0) 00257 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00258 int response = _spi.write(0xFF); 00259 if (!(response & 0x80)) { 00260 _cs = 1; 00261 _spi.write(0xFF); 00262 return response; 00263 } 00264 } 00265 _cs = 1; 00266 _spi.write(0xFF); 00267 return -1; // timeout 00268 } 00269 int SDFileSystem::_cmdx(int cmd, int arg) { 00270 _cs = 0; 00271 00272 // send a command 00273 _spi.write(0x40 | cmd); 00274 _spi.write(arg >> 24); 00275 _spi.write(arg >> 16); 00276 _spi.write(arg >> 8); 00277 _spi.write(arg >> 0); 00278 _spi.write(0x95); 00279 00280 // wait for the repsonse (response[7] == 0) 00281 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00282 int response = _spi.write(0xFF); 00283 if (!(response & 0x80)) { 00284 return response; 00285 } 00286 } 00287 _cs = 1; 00288 _spi.write(0xFF); 00289 return -1; // timeout 00290 } 00291 00292 00293 int SDFileSystem::_cmd58() { 00294 _cs = 0; 00295 int arg = 0; 00296 00297 // send a command 00298 _spi.write(0x40 | 58); 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 int ocr = _spi.write(0xFF) << 24; 00310 ocr |= _spi.write(0xFF) << 16; 00311 ocr |= _spi.write(0xFF) << 8; 00312 ocr |= _spi.write(0xFF) << 0; 00313 _cs = 1; 00314 _spi.write(0xFF); 00315 return response; 00316 } 00317 } 00318 _cs = 1; 00319 _spi.write(0xFF); 00320 return -1; // timeout 00321 } 00322 00323 int SDFileSystem::_cmd8() { 00324 _cs = 0; 00325 00326 // send a command 00327 _spi.write(0x40 | 8); // CMD8 00328 _spi.write(0x00); // reserved 00329 _spi.write(0x00); // reserved 00330 _spi.write(0x01); // 3.3v 00331 _spi.write(0xAA); // check pattern 00332 _spi.write(0x87); // crc 00333 00334 // wait for the repsonse (response[7] == 0) 00335 for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) { 00336 char response[5]; 00337 response[0] = _spi.write(0xFF); 00338 if (!(response[0] & 0x80)) { 00339 for (int j = 1; j < 5; j++) { 00340 response[i] = _spi.write(0xFF); 00341 } 00342 _cs = 1; 00343 _spi.write(0xFF); 00344 return response[0]; 00345 } 00346 } 00347 _cs = 1; 00348 _spi.write(0xFF); 00349 return -1; // timeout 00350 } 00351 00352 int SDFileSystem::_read(uint8_t *buffer, uint32_t length) { 00353 _cs = 0; 00354 00355 // read until start byte (0xFF) 00356 while (_spi.write(0xFF) != 0xFE); 00357 00358 // read data 00359 for (int i = 0; i < length; i++) { 00360 buffer[i] = _spi.write(0xFF); 00361 } 00362 _spi.write(0xFF); // checksum 00363 _spi.write(0xFF); 00364 00365 _cs = 1; 00366 _spi.write(0xFF); 00367 return 0; 00368 } 00369 00370 int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) { 00371 _cs = 0; 00372 00373 // indicate start of block 00374 _spi.write(0xFE); 00375 00376 // write the data 00377 for (int i = 0; i < length; i++) { 00378 _spi.write(buffer[i]); 00379 } 00380 00381 // write the checksum 00382 _spi.write(0xFF); 00383 _spi.write(0xFF); 00384 00385 // check the response token 00386 if ((_spi.write(0xFF) & 0x1F) != 0x05) { 00387 _cs = 1; 00388 _spi.write(0xFF); 00389 return 1; 00390 } 00391 00392 // wait for write to finish 00393 while (_spi.write(0xFF) == 0); 00394 00395 _cs = 1; 00396 _spi.write(0xFF); 00397 return 0; 00398 } 00399 00400 static uint32_t ext_bits(unsigned char *data, int msb, int lsb) { 00401 uint32_t bits = 0; 00402 uint32_t size = 1 + msb - lsb; 00403 for (int i = 0; i < size; i++) { 00404 uint32_t position = lsb + i; 00405 uint32_t byte = 15 - (position >> 3); 00406 uint32_t bit = position & 0x7; 00407 uint32_t value = (data[byte] >> bit) & 1; 00408 bits |= value << i; 00409 } 00410 return bits; 00411 } 00412 00413 uint64_t SDFileSystem::_sd_sectors() { 00414 uint32_t c_size, c_size_mult, read_bl_len; 00415 uint32_t block_len, mult, blocknr, capacity; 00416 uint32_t hc_c_size; 00417 uint64_t blocks; 00418 00419 // CMD9, Response R2 (R1 byte + 16-byte block read) 00420 if (_cmdx(9, 0) != 0) { 00421 debug("Didn't get a response from the disk\n"); 00422 return 0; 00423 } 00424 00425 uint8_t csd[16]; 00426 if (_read(csd, 16) != 0) { 00427 debug("Couldn't read csd response from disk\n"); 00428 return 0; 00429 } 00430 00431 // csd_structure : csd[127:126] 00432 // c_size : csd[73:62] 00433 // c_size_mult : csd[49:47] 00434 // read_bl_len : csd[83:80] - the *maximum* read block length 00435 00436 int csd_structure = ext_bits(csd, 127, 126); 00437 00438 switch (csd_structure) { 00439 case 0: 00440 cdv = 512; 00441 c_size = ext_bits(csd, 73, 62); 00442 c_size_mult = ext_bits(csd, 49, 47); 00443 read_bl_len = ext_bits(csd, 83, 80); 00444 00445 block_len = 1 << read_bl_len; 00446 mult = 1 << (c_size_mult + 2); 00447 blocknr = (c_size + 1) * mult; 00448 capacity = blocknr * block_len; 00449 blocks = capacity / 512; 00450 debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks); 00451 break; 00452 00453 case 1: 00454 cdv = 1; 00455 hc_c_size = ext_bits(csd, 63, 48); 00456 blocks = (hc_c_size+1)*1024; 00457 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); 00458 break; 00459 00460 default: 00461 debug("CSD struct unsupported\r\n"); 00462 return 0; 00463 }; 00464 return blocks; 00465 }
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