SDFileSystem with mutex for multiple SPI devices on the same SPI bus
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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 00023 /* Introduction 00024 * ------------ 00025 * SD and MMC cards support a number of interfaces, but common to them all 00026 * is one based on SPI. This is the one I'm implmenting because it means 00027 * it is much more portable even though not so performant, and we already 00028 * have the mbed SPI Interface! 00029 * 00030 * The main reference I'm using is Chapter 7, "SPI Mode" of: 00031 * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf 00032 * 00033 * SPI Startup 00034 * ----------- 00035 * The SD card powers up in SD mode. The SPI interface mode is selected by 00036 * asserting CS low and sending the reset command (CMD0). The card will 00037 * respond with a (R1) response. 00038 * 00039 * CMD8 is optionally sent to determine the voltage range supported, and 00040 * indirectly determine whether it is a version 1.x SD/non-SD card or 00041 * version 2.x. I'll just ignore this for now. 00042 * 00043 * ACMD41 is repeatedly issued to initialise the card, until "in idle" 00044 * (bit 0) of the R1 response goes to '0', indicating it is initialised. 00045 * 00046 * You should also indicate whether the host supports High Capicity cards, 00047 * and check whether the card is high capacity - i'll also ignore this 00048 * 00049 * SPI Protocol 00050 * ------------ 00051 * The SD SPI protocol is based on transactions made up of 8-bit words, with 00052 * the host starting every bus transaction by asserting the CS signal low. The 00053 * card always responds to commands, data blocks and errors. 00054 * 00055 * The protocol supports a CRC, but by default it is off (except for the 00056 * first reset CMD0, where the CRC can just be pre-calculated, and CMD8) 00057 * I'll leave the CRC off I think! 00058 * 00059 * Standard capacity cards have variable data block sizes, whereas High 00060 * Capacity cards fix the size of data block to 512 bytes. I'll therefore 00061 * just always use the Standard Capacity cards with a block size of 512 bytes. 00062 * This is set with CMD16. 00063 * 00064 * You can read and write single blocks (CMD17, CMD25) or multiple blocks 00065 * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When 00066 * the card gets a read command, it responds with a response token, and then 00067 * a data token or an error. 00068 * 00069 * SPI Command Format 00070 * ------------------ 00071 * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC. 00072 * 00073 * +---------------+------------+------------+-----------+----------+--------------+ 00074 * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 | 00075 * +---------------+------------+------------+-----------+----------+--------------+ 00076 * 00077 * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95) 00078 * 00079 * All Application Specific commands shall be preceded with APP_CMD (CMD55). 00080 * 00081 * SPI Response Format 00082 * ------------------- 00083 * The main response format (R1) is a status byte (normally zero). Key flags: 00084 * idle - 1 if the card is in an idle state/initialising 00085 * cmd - 1 if an illegal command code was detected 00086 * 00087 * +-------------------------------------------------+ 00088 * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle | 00089 * +-------------------------------------------------+ 00090 * 00091 * R1b is the same, except it is followed by a busy signal (zeros) until 00092 * the first non-zero byte when it is ready again. 00093 * 00094 * Data Response Token 00095 * ------------------- 00096 * Every data block written to the card is acknowledged by a byte 00097 * response token 00098 * 00099 * +----------------------+ 00100 * | xxx | 0 | status | 1 | 00101 * +----------------------+ 00102 * 010 - OK! 00103 * 101 - CRC Error 00104 * 110 - Write Error 00105 * 00106 * Single Block Read and Write 00107 * --------------------------- 00108 * 00109 * Block transfers have a byte header, followed by the data, followed 00110 * by a 16-bit CRC. In our case, the data will always be 512 bytes. 00111 * 00112 * +------+---------+---------+- - - -+---------+-----------+----------+ 00113 * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] | 00114 * +------+---------+---------+- - - -+---------+-----------+----------+ 00115 */ 00116 #include "SDFileSystem.h" 00117 #include "mbed_debug.h" 00118 00119 #define SD_COMMAND_TIMEOUT 5000 00120 00121 #define SD_DBG 0 00122 00123 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, Mutex & mutex, const char* name) : 00124 FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs), _mutex(mutex) { 00125 _cs = 1; 00126 } 00127 00128 #define R1_IDLE_STATE (1 << 0) 00129 #define R1_ERASE_RESET (1 << 1) 00130 #define R1_ILLEGAL_COMMAND (1 << 2) 00131 #define R1_COM_CRC_ERROR (1 << 3) 00132 #define R1_ERASE_SEQUENCE_ERROR (1 << 4) 00133 #define R1_ADDRESS_ERROR (1 << 5) 00134 #define R1_PARAMETER_ERROR (1 << 6) 00135 00136 // Types 00137 #define SDCARD_FAIL 0 //!< v1.x Standard Capacity 00138 #define SDCARD_V1 1 //!< v2.x Standard Capacity 00139 #define SDCARD_V2 2 //!< v2.x High Capacity 00140 #define SDCARD_V2HC 3 //!< Not recognised as an SD Card 00141 00142 int SDFileSystem::initialise_card() { 00143 // Set to 100kHz for initialisation, and clock card with cs = 1 00144 _spi.frequency(100000); 00145 _mutex.lock(); 00146 _cs = 1; 00147 for (int i = 0; i < 16; i++) { 00148 _spi.write(0xFF); 00149 } 00150 _mutex.unlock(); 00151 00152 // send CMD0, should return with all zeros except IDLE STATE set (bit 0) 00153 if (_cmd(0, 0) != R1_IDLE_STATE) { 00154 debug("No disk, or could not put SD card in to SPI idle state\n"); 00155 return SDCARD_FAIL; 00156 } 00157 00158 // send CMD8 to determine whther it is ver 2.x 00159 int r = _cmd8(); 00160 if (r == R1_IDLE_STATE) { 00161 return initialise_card_v2(); 00162 } else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) { 00163 return initialise_card_v1(); 00164 } else { 00165 debug("Not in idle state after sending CMD8 (not an SD card?)\n"); 00166 return SDCARD_FAIL; 00167 } 00168 } 00169 00170 int SDFileSystem::initialise_card_v1() { 00171 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00172 _cmd(55, 0); 00173 if (_cmd(41, 0) == 0) { 00174 cdv = 512; 00175 debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r"); 00176 return SDCARD_V1; 00177 } 00178 } 00179 00180 debug("Timeout waiting for v1.x card\n"); 00181 return SDCARD_FAIL; 00182 } 00183 00184 int SDFileSystem::initialise_card_v2() { 00185 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00186 wait_ms(50); 00187 _cmd58(); 00188 _cmd(55, 0); 00189 if (_cmd(41, 0x40000000) == 0) { 00190 _cmd58(); 00191 debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r"); 00192 cdv = 1; 00193 return SDCARD_V2; 00194 } 00195 } 00196 00197 debug("Timeout waiting for v2.x card\n"); 00198 return SDCARD_FAIL; 00199 } 00200 00201 int SDFileSystem::disk_initialize() { 00202 int i = initialise_card(); 00203 debug_if(SD_DBG, "init card = %d\n", i); 00204 _sectors = _sd_sectors(); 00205 00206 // Set block length to 512 (CMD16) 00207 if (_cmd(16, 512) != 0) { 00208 debug("Set 512-byte block timed out\n"); 00209 return 1; 00210 } 00211 00212 _spi.frequency(1000000); // Set to 1MHz for data transfer 00213 return 0; 00214 } 00215 00216 int SDFileSystem::disk_write(const uint8_t *buffer, uint64_t block_number) { 00217 // set write address for single block (CMD24) 00218 if (_cmd(24, block_number * cdv) != 0) { 00219 return 1; 00220 } 00221 00222 // send the data block 00223 _write(buffer, 512); 00224 return 0; 00225 } 00226 00227 int SDFileSystem::disk_read(uint8_t *buffer, uint64_t block_number) { 00228 // set read address for single block (CMD17) 00229 if (_cmd(17, block_number * cdv) != 0) { 00230 return 1; 00231 } 00232 00233 // receive the data 00234 _read(buffer, 512); 00235 return 0; 00236 } 00237 00238 int SDFileSystem::disk_status() { return 0; } 00239 int SDFileSystem::disk_sync() { return 0; } 00240 uint64_t SDFileSystem::disk_sectors() { return _sectors; } 00241 00242 00243 // PRIVATE FUNCTIONS 00244 int SDFileSystem::_cmd(int cmd, int arg) { 00245 _mutex.lock(); 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 _mutex.unlock(); 00263 return response; 00264 } 00265 } 00266 _cs = 1; 00267 _spi.write(0xFF); 00268 _mutex.unlock(); 00269 return -1; // timeout 00270 } 00271 int SDFileSystem::_cmdx(int cmd, int arg) { 00272 _mutex.lock(); 00273 _cs = 0; 00274 00275 // send a command 00276 _spi.write(0x40 | cmd); 00277 _spi.write(arg >> 24); 00278 _spi.write(arg >> 16); 00279 _spi.write(arg >> 8); 00280 _spi.write(arg >> 0); 00281 _spi.write(0x95); 00282 00283 // wait for the repsonse (response[7] == 0) 00284 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00285 int response = _spi.write(0xFF); 00286 if (!(response & 0x80)) { 00287 return response; 00288 } 00289 } 00290 _cs = 1; 00291 _spi.write(0xFF); 00292 _mutex.unlock(); 00293 return -1; // timeout 00294 } 00295 00296 00297 int SDFileSystem::_cmd58() { 00298 _mutex.lock(); 00299 _cs = 0; 00300 int arg = 0; 00301 00302 // send a command 00303 _spi.write(0x40 | 58); 00304 _spi.write(arg >> 24); 00305 _spi.write(arg >> 16); 00306 _spi.write(arg >> 8); 00307 _spi.write(arg >> 0); 00308 _spi.write(0x95); 00309 00310 // wait for the repsonse (response[7] == 0) 00311 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00312 int response = _spi.write(0xFF); 00313 if (!(response & 0x80)) { 00314 int ocr = _spi.write(0xFF) << 24; 00315 ocr |= _spi.write(0xFF) << 16; 00316 ocr |= _spi.write(0xFF) << 8; 00317 ocr |= _spi.write(0xFF) << 0; 00318 _cs = 1; 00319 _spi.write(0xFF); 00320 _mutex.unlock(); 00321 return response; 00322 } 00323 } 00324 _cs = 1; 00325 _spi.write(0xFF); 00326 _mutex.unlock(); 00327 return -1; // timeout 00328 } 00329 00330 int SDFileSystem::_cmd8() { 00331 _mutex.lock(); 00332 _cs = 0; 00333 00334 // send a command 00335 _spi.write(0x40 | 8); // CMD8 00336 _spi.write(0x00); // reserved 00337 _spi.write(0x00); // reserved 00338 _spi.write(0x01); // 3.3v 00339 _spi.write(0xAA); // check pattern 00340 _spi.write(0x87); // crc 00341 00342 // wait for the repsonse (response[7] == 0) 00343 for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) { 00344 char response[5]; 00345 response[0] = _spi.write(0xFF); 00346 if (!(response[0] & 0x80)) { 00347 for (int j = 1; j < 5; j++) { 00348 response[i] = _spi.write(0xFF); 00349 } 00350 _cs = 1; 00351 _spi.write(0xFF); 00352 _mutex.unlock(); 00353 return response[0]; 00354 } 00355 } 00356 _cs = 1; 00357 _spi.write(0xFF); 00358 _mutex.unlock(); 00359 return -1; // timeout 00360 } 00361 00362 int SDFileSystem::_read(uint8_t *buffer, uint32_t length) { 00363 _mutex.lock(); 00364 _cs = 0; 00365 00366 // read until start byte (0xFF) 00367 while (_spi.write(0xFF) != 0xFE); 00368 00369 // read data 00370 for (int i = 0; i < length; i++) { 00371 buffer[i] = _spi.write(0xFF); 00372 } 00373 _spi.write(0xFF); // checksum 00374 _spi.write(0xFF); 00375 00376 _cs = 1; 00377 _spi.write(0xFF); 00378 _mutex.unlock(); 00379 return 0; 00380 } 00381 00382 int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) { 00383 _mutex.lock(); 00384 _cs = 0; 00385 00386 // indicate start of block 00387 _spi.write(0xFE); 00388 00389 // write the data 00390 for (int i = 0; i < length; i++) { 00391 _spi.write(buffer[i]); 00392 } 00393 00394 // write the checksum 00395 _spi.write(0xFF); 00396 _spi.write(0xFF); 00397 00398 // check the response token 00399 if ((_spi.write(0xFF) & 0x1F) != 0x05) { 00400 _cs = 1; 00401 _spi.write(0xFF); 00402 _mutex.unlock(); 00403 return 1; 00404 } 00405 00406 // wait for write to finish 00407 while (_spi.write(0xFF) == 0); 00408 00409 _cs = 1; 00410 _spi.write(0xFF); 00411 _mutex.unlock(); 00412 return 0; 00413 } 00414 00415 static uint32_t ext_bits(unsigned char *data, int msb, int lsb) { 00416 uint32_t bits = 0; 00417 uint32_t size = 1 + msb - lsb; 00418 for (int i = 0; i < size; i++) { 00419 uint32_t position = lsb + i; 00420 uint32_t byte = 15 - (position >> 3); 00421 uint32_t bit = position & 0x7; 00422 uint32_t value = (data[byte] >> bit) & 1; 00423 bits |= value << i; 00424 } 00425 return bits; 00426 } 00427 00428 uint64_t SDFileSystem::_sd_sectors() { 00429 uint32_t c_size, c_size_mult, read_bl_len; 00430 uint32_t block_len, mult, blocknr, capacity; 00431 uint32_t hc_c_size; 00432 uint64_t blocks; 00433 00434 // CMD9, Response R2 (R1 byte + 16-byte block read) 00435 if (_cmdx(9, 0) != 0) { 00436 debug("Didn't get a response from the disk\n"); 00437 return 0; 00438 } 00439 00440 uint8_t csd[16]; 00441 if (_read(csd, 16) != 0) { 00442 debug("Couldn't read csd response from disk\n"); 00443 return 0; 00444 } 00445 00446 // csd_structure : csd[127:126] 00447 // c_size : csd[73:62] 00448 // c_size_mult : csd[49:47] 00449 // read_bl_len : csd[83:80] - the *maximum* read block length 00450 00451 int csd_structure = ext_bits(csd, 127, 126); 00452 00453 switch (csd_structure) { 00454 case 0: 00455 cdv = 512; 00456 c_size = ext_bits(csd, 73, 62); 00457 c_size_mult = ext_bits(csd, 49, 47); 00458 read_bl_len = ext_bits(csd, 83, 80); 00459 00460 block_len = 1 << read_bl_len; 00461 mult = 1 << (c_size_mult + 2); 00462 blocknr = (c_size + 1) * mult; 00463 capacity = blocknr * block_len; 00464 blocks = capacity / 512; 00465 debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks); 00466 break; 00467 00468 case 1: 00469 cdv = 1; 00470 hc_c_size = ext_bits(csd, 63, 48); 00471 blocks = (hc_c_size+1)*1024; 00472 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); 00473 break; 00474 00475 default: 00476 debug("CSD struct unsupported\r\n"); 00477 return 0; 00478 }; 00479 return blocks; 00480 }
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