test
Dependencies: FatFileSystem TextLCD mbed
SDFileSystem.cpp
00001 /* mbed SDFileSystem Library, for providing file access to SD cards 00002 * Copyright (c) 2008-2010, sford 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 00020 * THE 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 00117 #include "SDFileSystem.h" 00118 00119 #define SD_COMMAND_TIMEOUT 5000 00120 00121 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) : 00122 FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) { 00123 _cs = 1; 00124 } 00125 00126 #define R1_IDLE_STATE (1 << 0) 00127 #define R1_ERASE_RESET (1 << 1) 00128 #define R1_ILLEGAL_COMMAND (1 << 2) 00129 #define R1_COM_CRC_ERROR (1 << 3) 00130 #define R1_ERASE_SEQUENCE_ERROR (1 << 4) 00131 #define R1_ADDRESS_ERROR (1 << 5) 00132 #define R1_PARAMETER_ERROR (1 << 6) 00133 00134 // Types 00135 // - v1.x Standard Capacity 00136 // - v2.x Standard Capacity 00137 // - v2.x High Capacity 00138 // - Not recognised as an SD Card 00139 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(100000); 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 fprintf(stderr, "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 fprintf(stderr, "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 return SDCARD_V1; 00176 } 00177 } 00178 00179 fprintf(stderr, "Timeout waiting for v1.x card\n"); 00180 return SDCARD_FAIL; 00181 } 00182 00183 int SDFileSystem::initialise_card_v2() { 00184 00185 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { 00186 _cmd(55, 0); 00187 if(_cmd(41, 0) == 0) { 00188 _cmd58(); 00189 return SDCARD_V2; 00190 } 00191 } 00192 00193 fprintf(stderr, "Timeout waiting for v2.x card\n"); 00194 return SDCARD_FAIL; 00195 } 00196 00197 int SDFileSystem::disk_initialize() { 00198 00199 int i = initialise_card(); 00200 // printf("init card = %d\n", i); 00201 // printf("OK\n"); 00202 00203 _sectors = _sd_sectors(); 00204 00205 // Set block length to 512 (CMD16) 00206 if(_cmd(16, 512) != 0) { 00207 fprintf(stderr, "Set 512-byte block timed out\n"); 00208 return 1; 00209 } 00210 00211 // _spi.frequency(1000000); // Set to 1MHz for data transfer 00212 _spi.frequency(5000000); // Set to 1MHz for data transfer 00213 return 0; 00214 } 00215 00216 int SDFileSystem::disk_write(const char *buffer, int block_number) { 00217 // set write address for single block (CMD24) 00218 if(_cmd(24, block_number * 512) != 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(char *buffer, int block_number) { 00228 // set read address for single block (CMD17) 00229 if(_cmd(17, block_number * 512) != 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 int SDFileSystem::disk_sectors() { return _sectors; } 00241 00242 // PRIVATE FUNCTIONS 00243 00244 int SDFileSystem::_cmd(int cmd, int arg) { 00245 _cs = 0; 00246 00247 // send a command 00248 _spi.write(0x40 | cmd); 00249 _spi.write(arg >> 24); 00250 _spi.write(arg >> 16); 00251 _spi.write(arg >> 8); 00252 _spi.write(arg >> 0); 00253 _spi.write(0x95); 00254 00255 // wait for the repsonse (response[7] == 0) 00256 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { 00257 int response = _spi.write(0xFF); 00258 if(!(response & 0x80)) { 00259 _cs = 1; 00260 _spi.write(0xFF); 00261 return response; 00262 } 00263 } 00264 _cs = 1; 00265 _spi.write(0xFF); 00266 return -1; // timeout 00267 } 00268 int SDFileSystem::_cmdx(int cmd, int arg) { 00269 _cs = 0; 00270 00271 // send a command 00272 _spi.write(0x40 | cmd); 00273 _spi.write(arg >> 24); 00274 _spi.write(arg >> 16); 00275 _spi.write(arg >> 8); 00276 _spi.write(arg >> 0); 00277 _spi.write(0x95); 00278 00279 // wait for the repsonse (response[7] == 0) 00280 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { 00281 int response = _spi.write(0xFF); 00282 if(!(response & 0x80)) { 00283 return response; 00284 } 00285 } 00286 _cs = 1; 00287 _spi.write(0xFF); 00288 return -1; // timeout 00289 } 00290 00291 00292 int SDFileSystem::_cmd58() { 00293 _cs = 0; 00294 int arg = 0; 00295 00296 // send a command 00297 _spi.write(0x40 | 58); 00298 _spi.write(arg >> 24); 00299 _spi.write(arg >> 16); 00300 _spi.write(arg >> 8); 00301 _spi.write(arg >> 0); 00302 _spi.write(0x95); 00303 00304 // wait for the repsonse (response[7] == 0) 00305 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { 00306 int response = _spi.write(0xFF); 00307 if(!(response & 0x80)) { 00308 int ocr = _spi.write(0xFF) << 24; 00309 ocr |= _spi.write(0xFF) << 16; 00310 ocr |= _spi.write(0xFF) << 8; 00311 ocr |= _spi.write(0xFF) << 0; 00312 // printf("OCR = 0x%08X\n", ocr); 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(char *buffer, int 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 char *buffer, int 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 repsonse 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 int ext_bits(char *data, int msb, int lsb) { 00401 int bits = 0; 00402 int size = 1 + msb - lsb; 00403 for(int i=0; i<size; i++) { 00404 int position = lsb + i; 00405 int byte = 15 - (position >> 3); 00406 int bit = position & 0x7; 00407 int value = (data[byte] >> bit) & 1; 00408 bits |= value << i; 00409 } 00410 return bits; 00411 } 00412 00413 int SDFileSystem::_sd_sectors() { 00414 00415 // CMD9, Response R2 (R1 byte + 16-byte block read) 00416 if(_cmdx(9, 0) != 0) { 00417 fprintf(stderr, "Didn't get a response from the disk\n"); 00418 return 0; 00419 } 00420 00421 char csd[16]; 00422 if(_read(csd, 16) != 0) { 00423 fprintf(stderr, "Couldn't read csd response from disk\n"); 00424 return 0; 00425 } 00426 00427 // csd_structure : csd[127:126] 00428 // c_size : csd[73:62] 00429 // c_size_mult : csd[49:47] 00430 // read_bl_len : csd[83:80] - the *maximum* read block length 00431 00432 int csd_structure = ext_bits(csd, 127, 126); 00433 int c_size = ext_bits(csd, 73, 62); 00434 int c_size_mult = ext_bits(csd, 49, 47); 00435 int read_bl_len = ext_bits(csd, 83, 80); 00436 00437 // printf("CSD_STRUCT = %d\n", csd_structure); 00438 00439 if(csd_structure != 0) { 00440 fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n"); 00441 return 0; 00442 } 00443 00444 // memory capacity = BLOCKNR * BLOCK_LEN 00445 // where 00446 // BLOCKNR = (C_SIZE+1) * MULT 00447 // MULT = 2^(C_SIZE_MULT+2) (C_SIZE_MULT < 8) 00448 // BLOCK_LEN = 2^READ_BL_LEN, (READ_BL_LEN < 12) 00449 00450 int block_len = 1 << read_bl_len; 00451 int mult = 1 << (c_size_mult + 2); 00452 int blocknr = (c_size + 1) * mult; 00453 int capacity = blocknr * block_len; 00454 00455 int blocks = capacity / 512; 00456 00457 return blocks; 00458 }
Generated on Wed Jul 13 2022 12:25:58 by 1.7.2