USBMSD example using an SD card
Dependents: USBMSD_SD_HelloWorld_FRDM-KL25Z USBMSD_SD_HelloWorld_Mbed USBMSD_SD_HelloWorld_FRDM-KL25Z V09_01h ... more
USBMSD_SD.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 "USBMSD_SD.h" 00116 #include "mbed_debug.h" 00117 00118 #define SD_COMMAND_TIMEOUT 5000 00119 00120 #define SD_DBG 0 00121 00122 USBMSD_SD::USBMSD_SD(PinName mosi, PinName miso, PinName sclk, PinName cs) : 00123 _spi(mosi, miso, sclk), _cs(cs) { 00124 _cs = 1; 00125 00126 //no init 00127 _status = 0x01; 00128 00129 connect(); 00130 } 00131 00132 #define R1_IDLE_STATE (1 << 0) 00133 #define R1_ERASE_RESET (1 << 1) 00134 #define R1_ILLEGAL_COMMAND (1 << 2) 00135 #define R1_COM_CRC_ERROR (1 << 3) 00136 #define R1_ERASE_SEQUENCE_ERROR (1 << 4) 00137 #define R1_ADDRESS_ERROR (1 << 5) 00138 #define R1_PARAMETER_ERROR (1 << 6) 00139 00140 // Types 00141 // - v1.x Standard Capacity 00142 // - v2.x Standard Capacity 00143 // - v2.x High Capacity 00144 // - Not recognised as an SD Card 00145 #define SDCARD_FAIL 0 00146 #define SDCARD_V1 1 00147 #define SDCARD_V2 2 00148 #define SDCARD_V2HC 3 00149 00150 int USBMSD_SD::initialise_card() { 00151 // Set to 100kHz for initialisation, and clock card with cs = 1 00152 _spi.frequency(100000); 00153 _cs = 1; 00154 for (int i = 0; i < 16; i++) { 00155 _spi.write(0xFF); 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 USBMSD_SD::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 USBMSD_SD::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 USBMSD_SD::disk_initialize() { 00207 int i = initialise_card(); 00208 debug_if(SD_DBG, "init card = %d\n", i); 00209 _sectors = _sd_sectors(); 00210 00211 // Set block length to 512 (CMD16) 00212 if (_cmd(16, 512) != 0) { 00213 debug("Set 512-byte block timed out\n"); 00214 return 1; 00215 } 00216 00217 _spi.frequency(5000000); // Set to 5MHz for data transfer 00218 00219 // OK 00220 _status = 0x00; 00221 00222 return 0; 00223 } 00224 00225 int USBMSD_SD::disk_write(const uint8_t *buffer, uint64_t block_number) { 00226 // set write address for single block (CMD24) 00227 if (_cmd(24, block_number * cdv) != 0) { 00228 return 1; 00229 } 00230 00231 // send the data block 00232 _write(buffer, 512); 00233 return 0; 00234 } 00235 00236 int USBMSD_SD::disk_read(uint8_t *buffer, uint64_t block_number) { 00237 // set read address for single block (CMD17) 00238 if (_cmd(17, block_number * cdv) != 0) { 00239 return 1; 00240 } 00241 00242 // receive the data 00243 _read(buffer, 512); 00244 return 0; 00245 } 00246 00247 int USBMSD_SD::disk_status() { return _status; } 00248 int USBMSD_SD::disk_sync() { return 0; } 00249 uint64_t USBMSD_SD::disk_sectors() { return _sectors; } 00250 00251 00252 // PRIVATE FUNCTIONS 00253 int USBMSD_SD::_cmd(int cmd, int arg) { 00254 _cs = 0; 00255 00256 // send a command 00257 _spi.write(0x40 | cmd); 00258 _spi.write(arg >> 24); 00259 _spi.write(arg >> 16); 00260 _spi.write(arg >> 8); 00261 _spi.write(arg >> 0); 00262 _spi.write(0x95); 00263 00264 // wait for the repsonse (response[7] == 0) 00265 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00266 int response = _spi.write(0xFF); 00267 if (!(response & 0x80)) { 00268 _cs = 1; 00269 _spi.write(0xFF); 00270 return response; 00271 } 00272 } 00273 _cs = 1; 00274 _spi.write(0xFF); 00275 return -1; // timeout 00276 } 00277 int USBMSD_SD::_cmdx(int cmd, int arg) { 00278 _cs = 0; 00279 00280 // send a command 00281 _spi.write(0x40 | cmd); 00282 _spi.write(arg >> 24); 00283 _spi.write(arg >> 16); 00284 _spi.write(arg >> 8); 00285 _spi.write(arg >> 0); 00286 _spi.write(0x95); 00287 00288 // wait for the repsonse (response[7] == 0) 00289 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00290 int response = _spi.write(0xFF); 00291 if (!(response & 0x80)) { 00292 return response; 00293 } 00294 } 00295 _cs = 1; 00296 _spi.write(0xFF); 00297 return -1; // timeout 00298 } 00299 00300 00301 int USBMSD_SD::_cmd58() { 00302 _cs = 0; 00303 int arg = 0; 00304 00305 // send a command 00306 _spi.write(0x40 | 58); 00307 _spi.write(arg >> 24); 00308 _spi.write(arg >> 16); 00309 _spi.write(arg >> 8); 00310 _spi.write(arg >> 0); 00311 _spi.write(0x95); 00312 00313 // wait for the repsonse (response[7] == 0) 00314 for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { 00315 int response = _spi.write(0xFF); 00316 if (!(response & 0x80)) { 00317 int ocr = _spi.write(0xFF) << 24; 00318 ocr |= _spi.write(0xFF) << 16; 00319 ocr |= _spi.write(0xFF) << 8; 00320 ocr |= _spi.write(0xFF) << 0; 00321 _cs = 1; 00322 _spi.write(0xFF); 00323 return response; 00324 } 00325 } 00326 _cs = 1; 00327 _spi.write(0xFF); 00328 return -1; // timeout 00329 } 00330 00331 int USBMSD_SD::_cmd8() { 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 return response[0]; 00353 } 00354 } 00355 _cs = 1; 00356 _spi.write(0xFF); 00357 return -1; // timeout 00358 } 00359 00360 int USBMSD_SD::_read(uint8_t *buffer, uint32_t length) { 00361 _cs = 0; 00362 00363 // read until start byte (0xFF) 00364 while (_spi.write(0xFF) != 0xFE); 00365 00366 // read data 00367 for (int i = 0; i < length; i++) { 00368 buffer[i] = _spi.write(0xFF); 00369 } 00370 _spi.write(0xFF); // checksum 00371 _spi.write(0xFF); 00372 00373 _cs = 1; 00374 _spi.write(0xFF); 00375 return 0; 00376 } 00377 00378 int USBMSD_SD::_write(const uint8_t*buffer, uint32_t length) { 00379 _cs = 0; 00380 00381 // indicate start of block 00382 _spi.write(0xFE); 00383 00384 // write the data 00385 for (int i = 0; i < length; i++) { 00386 _spi.write(buffer[i]); 00387 } 00388 00389 // write the checksum 00390 _spi.write(0xFF); 00391 _spi.write(0xFF); 00392 00393 // check the response token 00394 if ((_spi.write(0xFF) & 0x1F) != 0x05) { 00395 _cs = 1; 00396 _spi.write(0xFF); 00397 return 1; 00398 } 00399 00400 // wait for write to finish 00401 while (_spi.write(0xFF) == 0); 00402 00403 _cs = 1; 00404 _spi.write(0xFF); 00405 return 0; 00406 } 00407 00408 static uint32_t ext_bits(unsigned char *data, int msb, int lsb) { 00409 uint32_t bits = 0; 00410 uint32_t size = 1 + msb - lsb; 00411 for (int i = 0; i < size; i++) { 00412 uint32_t position = lsb + i; 00413 uint32_t byte = 15 - (position >> 3); 00414 uint32_t bit = position & 0x7; 00415 uint32_t value = (data[byte] >> bit) & 1; 00416 bits |= value << i; 00417 } 00418 return bits; 00419 } 00420 00421 uint64_t USBMSD_SD::_sd_sectors() { 00422 uint32_t c_size, c_size_mult, read_bl_len; 00423 uint32_t block_len, mult, blocknr, capacity; 00424 uint32_t hc_c_size; 00425 uint64_t blocks; 00426 00427 // CMD9, Response R2 (R1 byte + 16-byte block read) 00428 if (_cmdx(9, 0) != 0) { 00429 debug("Didn't get a response from the disk\n"); 00430 return 0; 00431 } 00432 00433 uint8_t csd[16]; 00434 if (_read(csd, 16) != 0) { 00435 debug("Couldn't read csd response from disk\n"); 00436 return 0; 00437 } 00438 00439 // csd_structure : csd[127:126] 00440 // c_size : csd[73:62] 00441 // c_size_mult : csd[49:47] 00442 // read_bl_len : csd[83:80] - the *maximum* read block length 00443 00444 int csd_structure = ext_bits(csd, 127, 126); 00445 00446 switch (csd_structure) { 00447 case 0: 00448 cdv = 512; 00449 c_size = ext_bits(csd, 73, 62); 00450 c_size_mult = ext_bits(csd, 49, 47); 00451 read_bl_len = ext_bits(csd, 83, 80); 00452 00453 block_len = 1 << read_bl_len; 00454 mult = 1 << (c_size_mult + 2); 00455 blocknr = (c_size + 1) * mult; 00456 capacity = blocknr * block_len; 00457 blocks = capacity / 512; 00458 debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks); 00459 break; 00460 00461 case 1: 00462 cdv = 1; 00463 hc_c_size = ext_bits(csd, 63, 48); 00464 blocks = (hc_c_size+1)*1024; 00465 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); 00466 break; 00467 00468 default: 00469 debug("CSD struct unsupported\r\n"); 00470 return 0; 00471 }; 00472 return blocks; 00473 }
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