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Dependencies:   mbed

SDFileSystem.cpp@0:3c32eeb9292a, 2011-09-22 (annotated)

Committer:
geiineuville
Date:
Thu Sep 22 15:59:17 2011 +0000
Revision:
0:3c32eeb9292a
V4

Who changed what in which revision?

UserRevisionLine numberNew contents of line
geiineuville 0:3c32eeb9292a 1 /* mbed Microcontroller Library - SDFileSystem
geiineuville 0:3c32eeb9292a 2 * Copyright (c) 2008-2009, sford
geiineuville 0:3c32eeb9292a 3 *
geiineuville 0:3c32eeb9292a 4 * Introduction
geiineuville 0:3c32eeb9292a 5 * ------------
geiineuville 0:3c32eeb9292a 6 * SD and MMC cards support a number of interfaces, but common to them all
geiineuville 0:3c32eeb9292a 7 * is one based on SPI. This is the one I'm implmenting because it means
geiineuville 0:3c32eeb9292a 8 * it is much more portable even though not so performant, and we already
geiineuville 0:3c32eeb9292a 9 * have the mbed SPI Interface!
geiineuville 0:3c32eeb9292a 10 *
geiineuville 0:3c32eeb9292a 11 * The main reference I'm using is Chapter 7, "SPI Mode" of:
geiineuville 0:3c32eeb9292a 12 * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
geiineuville 0:3c32eeb9292a 13 *
geiineuville 0:3c32eeb9292a 14 * SPI Startup
geiineuville 0:3c32eeb9292a 15 * -----------
geiineuville 0:3c32eeb9292a 16 * The SD card powers up in SD mode. The SPI interface mode is selected by
geiineuville 0:3c32eeb9292a 17 * asserting CS low and sending the reset command (CMD0). The card will
geiineuville 0:3c32eeb9292a 18 * respond with a (R1) response.
geiineuville 0:3c32eeb9292a 19 *
geiineuville 0:3c32eeb9292a 20 * CMD8 is optionally sent to determine the voltage range supported, and
geiineuville 0:3c32eeb9292a 21 * indirectly determine whether it is a version 1.x SD/non-SD card or
geiineuville 0:3c32eeb9292a 22 * version 2.x. I'll just ignore this for now.
geiineuville 0:3c32eeb9292a 23 *
geiineuville 0:3c32eeb9292a 24 * ACMD41 is repeatedly issued to initialise the card, until "in idle"
geiineuville 0:3c32eeb9292a 25 * (bit 0) of the R1 response goes to '0', indicating it is initialised.
geiineuville 0:3c32eeb9292a 26 *
geiineuville 0:3c32eeb9292a 27 * You should also indicate whether the host supports High Capicity cards,
geiineuville 0:3c32eeb9292a 28 * and check whether the card is high capacity - i'll also ignore this
geiineuville 0:3c32eeb9292a 29 *
geiineuville 0:3c32eeb9292a 30 * SPI Protocol
geiineuville 0:3c32eeb9292a 31 * ------------
geiineuville 0:3c32eeb9292a 32 * The SD SPI protocol is based on transactions made up of 8-bit words, with
geiineuville 0:3c32eeb9292a 33 * the host starting every bus transaction by asserting the CS signal low. The
geiineuville 0:3c32eeb9292a 34 * card always responds to commands, data blocks and errors.
geiineuville 0:3c32eeb9292a 35 *
geiineuville 0:3c32eeb9292a 36 * The protocol supports a CRC, but by default it is off (except for the
geiineuville 0:3c32eeb9292a 37 * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
geiineuville 0:3c32eeb9292a 38 * I'll leave the CRC off I think!
geiineuville 0:3c32eeb9292a 39 *
geiineuville 0:3c32eeb9292a 40 * Standard capacity cards have variable data block sizes, whereas High
geiineuville 0:3c32eeb9292a 41 * Capacity cards fix the size of data block to 512 bytes. I'll therefore
geiineuville 0:3c32eeb9292a 42 * just always use the Standard Capacity cards with a block size of 512 bytes.
geiineuville 0:3c32eeb9292a 43 * This is set with CMD16.
geiineuville 0:3c32eeb9292a 44 *
geiineuville 0:3c32eeb9292a 45 * You can read and write single blocks (CMD17, CMD25) or multiple blocks
geiineuville 0:3c32eeb9292a 46 * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
geiineuville 0:3c32eeb9292a 47 * the card gets a read command, it responds with a response token, and then
geiineuville 0:3c32eeb9292a 48 * a data token or an error.
geiineuville 0:3c32eeb9292a 49 *
geiineuville 0:3c32eeb9292a 50 * SPI Command Format
geiineuville 0:3c32eeb9292a 51 * ------------------
geiineuville 0:3c32eeb9292a 52 * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
geiineuville 0:3c32eeb9292a 53 *
geiineuville 0:3c32eeb9292a 54 * +---------------+------------+------------+-----------+----------+--------------+
geiineuville 0:3c32eeb9292a 55 * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
geiineuville 0:3c32eeb9292a 56 * +---------------+------------+------------+-----------+----------+--------------+
geiineuville 0:3c32eeb9292a 57 *
geiineuville 0:3c32eeb9292a 58 * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
geiineuville 0:3c32eeb9292a 59 *
geiineuville 0:3c32eeb9292a 60 * All Application Specific commands shall be preceded with APP_CMD (CMD55).
geiineuville 0:3c32eeb9292a 61 *
geiineuville 0:3c32eeb9292a 62 * SPI Response Format
geiineuville 0:3c32eeb9292a 63 * -------------------
geiineuville 0:3c32eeb9292a 64 * The main response format (R1) is a status byte (normally zero). Key flags:
geiineuville 0:3c32eeb9292a 65 * idle - 1 if the card is in an idle state/initialising
geiineuville 0:3c32eeb9292a 66 * cmd - 1 if an illegal command code was detected
geiineuville 0:3c32eeb9292a 67 *
geiineuville 0:3c32eeb9292a 68 * +-------------------------------------------------+
geiineuville 0:3c32eeb9292a 69 * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
geiineuville 0:3c32eeb9292a 70 * +-------------------------------------------------+
geiineuville 0:3c32eeb9292a 71 *
geiineuville 0:3c32eeb9292a 72 * R1b is the same, except it is followed by a busy signal (zeros) until
geiineuville 0:3c32eeb9292a 73 * the first non-zero byte when it is ready again.
geiineuville 0:3c32eeb9292a 74 *
geiineuville 0:3c32eeb9292a 75 * Data Response Token
geiineuville 0:3c32eeb9292a 76 * -------------------
geiineuville 0:3c32eeb9292a 77 * Every data block written to the card is acknowledged by a byte
geiineuville 0:3c32eeb9292a 78 * response token
geiineuville 0:3c32eeb9292a 79 *
geiineuville 0:3c32eeb9292a 80 * +----------------------+
geiineuville 0:3c32eeb9292a 81 * | xxx | 0 | status | 1 |
geiineuville 0:3c32eeb9292a 82 * +----------------------+
geiineuville 0:3c32eeb9292a 83 * 010 - OK!
geiineuville 0:3c32eeb9292a 84 * 101 - CRC Error
geiineuville 0:3c32eeb9292a 85 * 110 - Write Error
geiineuville 0:3c32eeb9292a 86 *
geiineuville 0:3c32eeb9292a 87 * Single Block Read and Write
geiineuville 0:3c32eeb9292a 88 * ---------------------------
geiineuville 0:3c32eeb9292a 89 *
geiineuville 0:3c32eeb9292a 90 * Block transfers have a byte header, followed by the data, followed
geiineuville 0:3c32eeb9292a 91 * by a 16-bit CRC. In our case, the data will always be 512 bytes.
geiineuville 0:3c32eeb9292a 92 *
geiineuville 0:3c32eeb9292a 93 * +------+---------+---------+- - - -+---------+-----------+----------+
geiineuville 0:3c32eeb9292a 94 * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] |
geiineuville 0:3c32eeb9292a 95 * +------+---------+---------+- - - -+---------+-----------+----------+
geiineuville 0:3c32eeb9292a 96 */
geiineuville 0:3c32eeb9292a 97
geiineuville 0:3c32eeb9292a 98 #include "SDFileSystem.h"
geiineuville 0:3c32eeb9292a 99
geiineuville 0:3c32eeb9292a 100 #define SD_COMMAND_TIMEOUT 5000
geiineuville 0:3c32eeb9292a 101
geiineuville 0:3c32eeb9292a 102 //#define CR "\n"
geiineuville 0:3c32eeb9292a 103 #define CR "\r\n"
geiineuville 0:3c32eeb9292a 104
geiineuville 0:3c32eeb9292a 105 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
geiineuville 0:3c32eeb9292a 106 FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
geiineuville 0:3c32eeb9292a 107 _cs = 1;
geiineuville 0:3c32eeb9292a 108 }
geiineuville 0:3c32eeb9292a 109
geiineuville 0:3c32eeb9292a 110 #define R1_IDLE_STATE (1 << 0)
geiineuville 0:3c32eeb9292a 111 #define R1_ERASE_RESET (1 << 1)
geiineuville 0:3c32eeb9292a 112 #define R1_ILLEGAL_COMMAND (1 << 2)
geiineuville 0:3c32eeb9292a 113 #define R1_COM_CRC_ERROR (1 << 3)
geiineuville 0:3c32eeb9292a 114 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
geiineuville 0:3c32eeb9292a 115 #define R1_ADDRESS_ERROR (1 << 5)
geiineuville 0:3c32eeb9292a 116 #define R1_PARAMETER_ERROR (1 << 6)
geiineuville 0:3c32eeb9292a 117
geiineuville 0:3c32eeb9292a 118 int SDFileSystem::disk_initialize() {
geiineuville 0:3c32eeb9292a 119
geiineuville 0:3c32eeb9292a 120 _spi.frequency(100000); // Set to 100kHz for initialisation
geiineuville 0:3c32eeb9292a 121
geiineuville 0:3c32eeb9292a 122 // Initialise the card by clocking it a bit (cs = 1)
geiineuville 0:3c32eeb9292a 123 _cs = 1;
geiineuville 0:3c32eeb9292a 124 for(int i=0; i<16; i++) {
geiineuville 0:3c32eeb9292a 125 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 126 }
geiineuville 0:3c32eeb9292a 127
geiineuville 0:3c32eeb9292a 128 // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
geiineuville 0:3c32eeb9292a 129 if(_cmd(0, 0) != R1_IDLE_STATE) {
geiineuville 0:3c32eeb9292a 130 fprintf(stderr, "No disk, or could not put SD card into SPI idle state" CR);
geiineuville 0:3c32eeb9292a 131 return 1;
geiineuville 0:3c32eeb9292a 132 }
geiineuville 0:3c32eeb9292a 133
geiineuville 0:3c32eeb9292a 134 int r = _cmd8();
geiineuville 0:3c32eeb9292a 135 if(r == R1_IDLE_STATE) {
geiineuville 0:3c32eeb9292a 136 printf("SD version 2.x" CR);
geiineuville 0:3c32eeb9292a 137 } else if(r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
geiineuville 0:3c32eeb9292a 138 printf("SD version 1.x" CR);
geiineuville 0:3c32eeb9292a 139 } else {
geiineuville 0:3c32eeb9292a 140 error("Unknown SD version" CR);
geiineuville 0:3c32eeb9292a 141 }
geiineuville 0:3c32eeb9292a 142
geiineuville 0:3c32eeb9292a 143 // ACMD41 to give host capacity support (repeat until not busy)
geiineuville 0:3c32eeb9292a 144 // ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand
geiineuville 0:3c32eeb9292a 145 for(int i=0;; i++) {
geiineuville 0:3c32eeb9292a 146 _cmd(55, 0);
geiineuville 0:3c32eeb9292a 147 int response = _cmd(41, 0);
geiineuville 0:3c32eeb9292a 148 if(response == 0) {
geiineuville 0:3c32eeb9292a 149 break;
geiineuville 0:3c32eeb9292a 150 } else if(i > SD_COMMAND_TIMEOUT) {
geiineuville 0:3c32eeb9292a 151 fprintf(stderr, "Timeout waiting for card" CR);
geiineuville 0:3c32eeb9292a 152 return 1;
geiineuville 0:3c32eeb9292a 153 }
geiineuville 0:3c32eeb9292a 154 }
geiineuville 0:3c32eeb9292a 155
geiineuville 0:3c32eeb9292a 156 // printf("OK" CR);
geiineuville 0:3c32eeb9292a 157
geiineuville 0:3c32eeb9292a 158 _sectors = _sd_sectors();
geiineuville 0:3c32eeb9292a 159
geiineuville 0:3c32eeb9292a 160 // Set block length to 512 (CMD16)
geiineuville 0:3c32eeb9292a 161 if(_cmd(16, 512) != 0) {
geiineuville 0:3c32eeb9292a 162 fprintf(stderr, "Set block timeout" CR);
geiineuville 0:3c32eeb9292a 163 return 1;
geiineuville 0:3c32eeb9292a 164 }
geiineuville 0:3c32eeb9292a 165
geiineuville 0:3c32eeb9292a 166 _spi.frequency(1000000); // Set to 1MHz for data transfer
geiineuville 0:3c32eeb9292a 167 return 0;
geiineuville 0:3c32eeb9292a 168 }
geiineuville 0:3c32eeb9292a 169
geiineuville 0:3c32eeb9292a 170 int SDFileSystem::disk_write(const char *buffer, int block_number) {
geiineuville 0:3c32eeb9292a 171 // set write address for single block (CMD24)
geiineuville 0:3c32eeb9292a 172 if(_cmd(24, block_number * 512) != 0) {
geiineuville 0:3c32eeb9292a 173 return 1;
geiineuville 0:3c32eeb9292a 174 }
geiineuville 0:3c32eeb9292a 175
geiineuville 0:3c32eeb9292a 176 // send the data block
geiineuville 0:3c32eeb9292a 177 _write(buffer, 512);
geiineuville 0:3c32eeb9292a 178 return 0;
geiineuville 0:3c32eeb9292a 179 }
geiineuville 0:3c32eeb9292a 180
geiineuville 0:3c32eeb9292a 181 int SDFileSystem::disk_read(char *buffer, int block_number) {
geiineuville 0:3c32eeb9292a 182 // set read address for single block (CMD17)
geiineuville 0:3c32eeb9292a 183 if(_cmd(17, block_number * 512) != 0) {
geiineuville 0:3c32eeb9292a 184 return 1;
geiineuville 0:3c32eeb9292a 185 }
geiineuville 0:3c32eeb9292a 186
geiineuville 0:3c32eeb9292a 187 // receive the data
geiineuville 0:3c32eeb9292a 188 _read(buffer, 512);
geiineuville 0:3c32eeb9292a 189 return 0;
geiineuville 0:3c32eeb9292a 190 }
geiineuville 0:3c32eeb9292a 191
geiineuville 0:3c32eeb9292a 192 int SDFileSystem::disk_status() { return 0; }
geiineuville 0:3c32eeb9292a 193 int SDFileSystem::disk_sync() { return 0; }
geiineuville 0:3c32eeb9292a 194 int SDFileSystem::disk_sectors() { return _sectors; }
geiineuville 0:3c32eeb9292a 195
geiineuville 0:3c32eeb9292a 196 // PRIVATE FUNCTIONS
geiineuville 0:3c32eeb9292a 197
geiineuville 0:3c32eeb9292a 198 int SDFileSystem::_cmd(int cmd, int arg) {
geiineuville 0:3c32eeb9292a 199 _cs = 0;
geiineuville 0:3c32eeb9292a 200
geiineuville 0:3c32eeb9292a 201 // send a command
geiineuville 0:3c32eeb9292a 202 _spi.write(0x40 | cmd);
geiineuville 0:3c32eeb9292a 203 _spi.write(arg >> 24);
geiineuville 0:3c32eeb9292a 204 _spi.write(arg >> 16);
geiineuville 0:3c32eeb9292a 205 _spi.write(arg >> 8);
geiineuville 0:3c32eeb9292a 206 _spi.write(arg >> 0);
geiineuville 0:3c32eeb9292a 207 _spi.write(0x95);
geiineuville 0:3c32eeb9292a 208
geiineuville 0:3c32eeb9292a 209 // wait for the repsonse (response[7] == 0)
geiineuville 0:3c32eeb9292a 210 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
geiineuville 0:3c32eeb9292a 211 int response = _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 212 if(!(response & 0x80)) {
geiineuville 0:3c32eeb9292a 213 _cs = 1;
geiineuville 0:3c32eeb9292a 214 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 215 return response;
geiineuville 0:3c32eeb9292a 216 }
geiineuville 0:3c32eeb9292a 217 }
geiineuville 0:3c32eeb9292a 218 _cs = 1;
geiineuville 0:3c32eeb9292a 219 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 220 return -1; // timeout
geiineuville 0:3c32eeb9292a 221 }
geiineuville 0:3c32eeb9292a 222
geiineuville 0:3c32eeb9292a 223 int SDFileSystem::_cmd8() {
geiineuville 0:3c32eeb9292a 224 _cs = 0;
geiineuville 0:3c32eeb9292a 225
geiineuville 0:3c32eeb9292a 226 // send a command
geiineuville 0:3c32eeb9292a 227 _spi.write(0x40 | 8); // CMD8
geiineuville 0:3c32eeb9292a 228 _spi.write(0x00); // reserved
geiineuville 0:3c32eeb9292a 229 _spi.write(0x00); // reserved
geiineuville 0:3c32eeb9292a 230 _spi.write(0x01); // 3.3v
geiineuville 0:3c32eeb9292a 231 _spi.write(0xAA); // check pattern
geiineuville 0:3c32eeb9292a 232 _spi.write(0x87); // crc
geiineuville 0:3c32eeb9292a 233
geiineuville 0:3c32eeb9292a 234 // wait for the repsonse (response[7] == 0)
geiineuville 0:3c32eeb9292a 235 for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
geiineuville 0:3c32eeb9292a 236 char response[5];
geiineuville 0:3c32eeb9292a 237 response[0] = _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 238 if(!(response[0] & 0x80)) {
geiineuville 0:3c32eeb9292a 239 for(int j=1; j<5; j++) {
geiineuville 0:3c32eeb9292a 240 response[i] = _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 241 }
geiineuville 0:3c32eeb9292a 242 _cs = 1;
geiineuville 0:3c32eeb9292a 243 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 244 return response[0];
geiineuville 0:3c32eeb9292a 245 }
geiineuville 0:3c32eeb9292a 246 }
geiineuville 0:3c32eeb9292a 247 _cs = 1;
geiineuville 0:3c32eeb9292a 248 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 249 return -1; // timeout
geiineuville 0:3c32eeb9292a 250 }
geiineuville 0:3c32eeb9292a 251
geiineuville 0:3c32eeb9292a 252 int SDFileSystem::_read(char *buffer, int length) {
geiineuville 0:3c32eeb9292a 253 _cs = 0;
geiineuville 0:3c32eeb9292a 254
geiineuville 0:3c32eeb9292a 255 // read until start byte (0xFF)
geiineuville 0:3c32eeb9292a 256 while(_spi.write(0xFF) != 0xFE);
geiineuville 0:3c32eeb9292a 257
geiineuville 0:3c32eeb9292a 258 // read data
geiineuville 0:3c32eeb9292a 259 for(int i=0; i<length; i++) {
geiineuville 0:3c32eeb9292a 260 buffer[i] = _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 261 }
geiineuville 0:3c32eeb9292a 262 _spi.write(0xFF); // checksum
geiineuville 0:3c32eeb9292a 263 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 264
geiineuville 0:3c32eeb9292a 265 _cs = 1;
geiineuville 0:3c32eeb9292a 266 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 267 return 0;
geiineuville 0:3c32eeb9292a 268 }
geiineuville 0:3c32eeb9292a 269
geiineuville 0:3c32eeb9292a 270 int SDFileSystem::_write(const char *buffer, int length) {
geiineuville 0:3c32eeb9292a 271 _cs = 0;
geiineuville 0:3c32eeb9292a 272
geiineuville 0:3c32eeb9292a 273 // indicate start of block
geiineuville 0:3c32eeb9292a 274 _spi.write(0xFE);
geiineuville 0:3c32eeb9292a 275
geiineuville 0:3c32eeb9292a 276 // write the data
geiineuville 0:3c32eeb9292a 277 for(int i=0; i<length; i++) {
geiineuville 0:3c32eeb9292a 278 _spi.write(buffer[i]);
geiineuville 0:3c32eeb9292a 279 }
geiineuville 0:3c32eeb9292a 280
geiineuville 0:3c32eeb9292a 281 // write the checksum
geiineuville 0:3c32eeb9292a 282 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 283 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 284
geiineuville 0:3c32eeb9292a 285 // check the repsonse token
geiineuville 0:3c32eeb9292a 286 if((_spi.write(0xFF) & 0x1F) != 0x05) {
geiineuville 0:3c32eeb9292a 287 _cs = 1;
geiineuville 0:3c32eeb9292a 288 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 289 return 1;
geiineuville 0:3c32eeb9292a 290 }
geiineuville 0:3c32eeb9292a 291
geiineuville 0:3c32eeb9292a 292 // wait for write to finish
geiineuville 0:3c32eeb9292a 293 while(_spi.write(0xFF) == 0);
geiineuville 0:3c32eeb9292a 294
geiineuville 0:3c32eeb9292a 295 _cs = 1;
geiineuville 0:3c32eeb9292a 296 _spi.write(0xFF);
geiineuville 0:3c32eeb9292a 297 return 0;
geiineuville 0:3c32eeb9292a 298 }
geiineuville 0:3c32eeb9292a 299
geiineuville 0:3c32eeb9292a 300 static int ext_bits(char *data, int msb, int lsb) {
geiineuville 0:3c32eeb9292a 301 int bits = 0;
geiineuville 0:3c32eeb9292a 302 int size = 1 + msb - lsb;
geiineuville 0:3c32eeb9292a 303 for(int i=0; i<size; i++) {
geiineuville 0:3c32eeb9292a 304 int position = lsb + i;
geiineuville 0:3c32eeb9292a 305 int byte = 15 - (position >> 3);
geiineuville 0:3c32eeb9292a 306 int bit = position & 0x7;
geiineuville 0:3c32eeb9292a 307 int value = (data[byte] >> bit) & 1;
geiineuville 0:3c32eeb9292a 308 bits |= value << i;
geiineuville 0:3c32eeb9292a 309 }
geiineuville 0:3c32eeb9292a 310 return bits;
geiineuville 0:3c32eeb9292a 311 }
geiineuville 0:3c32eeb9292a 312
geiineuville 0:3c32eeb9292a 313 int SDFileSystem::_sd_sectors() {
geiineuville 0:3c32eeb9292a 314
geiineuville 0:3c32eeb9292a 315 // CMD9, Response R2 (R1 byte + 16-byte block read)
geiineuville 0:3c32eeb9292a 316 if(_cmd(9, 0) != 0) {
geiineuville 0:3c32eeb9292a 317 fprintf(stderr, "Didn't get a response from the disk" CR);
geiineuville 0:3c32eeb9292a 318 return 0;
geiineuville 0:3c32eeb9292a 319 }
geiineuville 0:3c32eeb9292a 320
geiineuville 0:3c32eeb9292a 321 char csd[16];
geiineuville 0:3c32eeb9292a 322 if(_read(csd, 16) != 0) {
geiineuville 0:3c32eeb9292a 323 fprintf(stderr, "Couldn't read csd response from disk" CR);
geiineuville 0:3c32eeb9292a 324 return 0;
geiineuville 0:3c32eeb9292a 325 }
geiineuville 0:3c32eeb9292a 326
geiineuville 0:3c32eeb9292a 327 // csd_structure : csd[127:126]
geiineuville 0:3c32eeb9292a 328 // c_size : csd[73:62]
geiineuville 0:3c32eeb9292a 329 // c_size_mult : csd[49:47]
geiineuville 0:3c32eeb9292a 330 // read_bl_len : csd[83:80]
geiineuville 0:3c32eeb9292a 331
geiineuville 0:3c32eeb9292a 332 int csd_structure = ext_bits(csd, 127, 126);
geiineuville 0:3c32eeb9292a 333 int c_size = ext_bits(csd, 73, 62);
geiineuville 0:3c32eeb9292a 334 int c_size_mult = ext_bits(csd, 49, 47);
geiineuville 0:3c32eeb9292a 335 int read_bl_len = ext_bits(csd, 83, 80);
geiineuville 0:3c32eeb9292a 336
geiineuville 0:3c32eeb9292a 337 if(csd_structure != 0) {
geiineuville 0:3c32eeb9292a 338 fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures" CR);
geiineuville 0:3c32eeb9292a 339 // Non-zero is SDHC.
geiineuville 0:3c32eeb9292a 340 return 0;
geiineuville 0:3c32eeb9292a 341 }
geiineuville 0:3c32eeb9292a 342
geiineuville 0:3c32eeb9292a 343 int blocks = (c_size + 1) * (1 << (c_size_mult + 2));
geiineuville 0:3c32eeb9292a 344 int block_size = 1 << read_bl_len;
geiineuville 0:3c32eeb9292a 345
geiineuville 0:3c32eeb9292a 346 if (block_size != 512 && block_size != 1024) {
geiineuville 0:3c32eeb9292a 347 fprintf(stderr, "This disk tastes funny! %d byte block. I only like 512 or 1024 -byte blocks" CR, block_size);
geiineuville 0:3c32eeb9292a 348 return 0;
geiineuville 0:3c32eeb9292a 349 }
geiineuville 0:3c32eeb9292a 350
geiineuville 0:3c32eeb9292a 351 return blocks;
geiineuville 0:3c32eeb9292a 352 }