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Dependencies:   mbed

SDFileSystem.cpp@0:83cf97c10b63, 2011-09-05 (annotated)

Committer:
geiineuville
Date:
Mon Sep 05 14:36:10 2011 +0000
Revision:
0:83cf97c10b63
webserver v 0 v 1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
geiineuville 0:83cf97c10b63 1 /* mbed Microcontroller Library - SDFileSystem
geiineuville 0:83cf97c10b63 2 * Copyright (c) 2008-2009, sford
geiineuville 0:83cf97c10b63 3 *
geiineuville 0:83cf97c10b63 4 * Introduction
geiineuville 0:83cf97c10b63 5 * ------------
geiineuville 0:83cf97c10b63 6 * SD and MMC cards support a number of interfaces, but common to them all
geiineuville 0:83cf97c10b63 7 * is one based on SPI. This is the one I'm implmenting because it means
geiineuville 0:83cf97c10b63 8 * it is much more portable even though not so performant, and we already
geiineuville 0:83cf97c10b63 9 * have the mbed SPI Interface!
geiineuville 0:83cf97c10b63 10 *
geiineuville 0:83cf97c10b63 11 * The main reference I'm using is Chapter 7, "SPI Mode" of:
geiineuville 0:83cf97c10b63 12 * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
geiineuville 0:83cf97c10b63 13 *
geiineuville 0:83cf97c10b63 14 * SPI Startup
geiineuville 0:83cf97c10b63 15 * -----------
geiineuville 0:83cf97c10b63 16 * The SD card powers up in SD mode. The SPI interface mode is selected by
geiineuville 0:83cf97c10b63 17 * asserting CS low and sending the reset command (CMD0). The card will
geiineuville 0:83cf97c10b63 18 * respond with a (R1) response.
geiineuville 0:83cf97c10b63 19 *
geiineuville 0:83cf97c10b63 20 * CMD8 is optionally sent to determine the voltage range supported, and
geiineuville 0:83cf97c10b63 21 * indirectly determine whether it is a version 1.x SD/non-SD card or
geiineuville 0:83cf97c10b63 22 * version 2.x. I'll just ignore this for now.
geiineuville 0:83cf97c10b63 23 *
geiineuville 0:83cf97c10b63 24 * ACMD41 is repeatedly issued to initialise the card, until "in idle"
geiineuville 0:83cf97c10b63 25 * (bit 0) of the R1 response goes to '0', indicating it is initialised.
geiineuville 0:83cf97c10b63 26 *
geiineuville 0:83cf97c10b63 27 * You should also indicate whether the host supports High Capicity cards,
geiineuville 0:83cf97c10b63 28 * and check whether the card is high capacity - i'll also ignore this
geiineuville 0:83cf97c10b63 29 *
geiineuville 0:83cf97c10b63 30 * SPI Protocol
geiineuville 0:83cf97c10b63 31 * ------------
geiineuville 0:83cf97c10b63 32 * The SD SPI protocol is based on transactions made up of 8-bit words, with
geiineuville 0:83cf97c10b63 33 * the host starting every bus transaction by asserting the CS signal low. The
geiineuville 0:83cf97c10b63 34 * card always responds to commands, data blocks and errors.
geiineuville 0:83cf97c10b63 35 *
geiineuville 0:83cf97c10b63 36 * The protocol supports a CRC, but by default it is off (except for the
geiineuville 0:83cf97c10b63 37 * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
geiineuville 0:83cf97c10b63 38 * I'll leave the CRC off I think!
geiineuville 0:83cf97c10b63 39 *
geiineuville 0:83cf97c10b63 40 * Standard capacity cards have variable data block sizes, whereas High
geiineuville 0:83cf97c10b63 41 * Capacity cards fix the size of data block to 512 bytes. I'll therefore
geiineuville 0:83cf97c10b63 42 * just always use the Standard Capacity cards with a block size of 512 bytes.
geiineuville 0:83cf97c10b63 43 * This is set with CMD16.
geiineuville 0:83cf97c10b63 44 *
geiineuville 0:83cf97c10b63 45 * You can read and write single blocks (CMD17, CMD25) or multiple blocks
geiineuville 0:83cf97c10b63 46 * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
geiineuville 0:83cf97c10b63 47 * the card gets a read command, it responds with a response token, and then
geiineuville 0:83cf97c10b63 48 * a data token or an error.
geiineuville 0:83cf97c10b63 49 *
geiineuville 0:83cf97c10b63 50 * SPI Command Format
geiineuville 0:83cf97c10b63 51 * ------------------
geiineuville 0:83cf97c10b63 52 * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
geiineuville 0:83cf97c10b63 53 *
geiineuville 0:83cf97c10b63 54 * +---------------+------------+------------+-----------+----------+--------------+
geiineuville 0:83cf97c10b63 55 * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
geiineuville 0:83cf97c10b63 56 * +---------------+------------+------------+-----------+----------+--------------+
geiineuville 0:83cf97c10b63 57 *
geiineuville 0:83cf97c10b63 58 * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
geiineuville 0:83cf97c10b63 59 *
geiineuville 0:83cf97c10b63 60 * All Application Specific commands shall be preceded with APP_CMD (CMD55).
geiineuville 0:83cf97c10b63 61 *
geiineuville 0:83cf97c10b63 62 * SPI Response Format
geiineuville 0:83cf97c10b63 63 * -------------------
geiineuville 0:83cf97c10b63 64 * The main response format (R1) is a status byte (normally zero). Key flags:
geiineuville 0:83cf97c10b63 65 * idle - 1 if the card is in an idle state/initialising
geiineuville 0:83cf97c10b63 66 * cmd - 1 if an illegal command code was detected
geiineuville 0:83cf97c10b63 67 *
geiineuville 0:83cf97c10b63 68 * +-------------------------------------------------+
geiineuville 0:83cf97c10b63 69 * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
geiineuville 0:83cf97c10b63 70 * +-------------------------------------------------+
geiineuville 0:83cf97c10b63 71 *
geiineuville 0:83cf97c10b63 72 * R1b is the same, except it is followed by a busy signal (zeros) until
geiineuville 0:83cf97c10b63 73 * the first non-zero byte when it is ready again.
geiineuville 0:83cf97c10b63 74 *
geiineuville 0:83cf97c10b63 75 * Data Response Token
geiineuville 0:83cf97c10b63 76 * -------------------
geiineuville 0:83cf97c10b63 77 * Every data block written to the card is acknowledged by a byte
geiineuville 0:83cf97c10b63 78 * response token
geiineuville 0:83cf97c10b63 79 *
geiineuville 0:83cf97c10b63 80 * +----------------------+
geiineuville 0:83cf97c10b63 81 * | xxx | 0 | status | 1 |
geiineuville 0:83cf97c10b63 82 * +----------------------+
geiineuville 0:83cf97c10b63 83 * 010 - OK!
geiineuville 0:83cf97c10b63 84 * 101 - CRC Error
geiineuville 0:83cf97c10b63 85 * 110 - Write Error
geiineuville 0:83cf97c10b63 86 *
geiineuville 0:83cf97c10b63 87 * Single Block Read and Write
geiineuville 0:83cf97c10b63 88 * ---------------------------
geiineuville 0:83cf97c10b63 89 *
geiineuville 0:83cf97c10b63 90 * Block transfers have a byte header, followed by the data, followed
geiineuville 0:83cf97c10b63 91 * by a 16-bit CRC. In our case, the data will always be 512 bytes.
geiineuville 0:83cf97c10b63 92 *
geiineuville 0:83cf97c10b63 93 * +------+---------+---------+- - - -+---------+-----------+----------+
geiineuville 0:83cf97c10b63 94 * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] |
geiineuville 0:83cf97c10b63 95 * +------+---------+---------+- - - -+---------+-----------+----------+
geiineuville 0:83cf97c10b63 96 */
geiineuville 0:83cf97c10b63 97
geiineuville 0:83cf97c10b63 98 #include "SDFileSystem.h"
geiineuville 0:83cf97c10b63 99
geiineuville 0:83cf97c10b63 100 #define SD_COMMAND_TIMEOUT 5000
geiineuville 0:83cf97c10b63 101
geiineuville 0:83cf97c10b63 102 //#define CR "\n"
geiineuville 0:83cf97c10b63 103 #define CR "\r\n"
geiineuville 0:83cf97c10b63 104
geiineuville 0:83cf97c10b63 105 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
geiineuville 0:83cf97c10b63 106 FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
geiineuville 0:83cf97c10b63 107 _cs = 1;
geiineuville 0:83cf97c10b63 108 }
geiineuville 0:83cf97c10b63 109
geiineuville 0:83cf97c10b63 110 #define R1_IDLE_STATE (1 << 0)
geiineuville 0:83cf97c10b63 111 #define R1_ERASE_RESET (1 << 1)
geiineuville 0:83cf97c10b63 112 #define R1_ILLEGAL_COMMAND (1 << 2)
geiineuville 0:83cf97c10b63 113 #define R1_COM_CRC_ERROR (1 << 3)
geiineuville 0:83cf97c10b63 114 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
geiineuville 0:83cf97c10b63 115 #define R1_ADDRESS_ERROR (1 << 5)
geiineuville 0:83cf97c10b63 116 #define R1_PARAMETER_ERROR (1 << 6)
geiineuville 0:83cf97c10b63 117
geiineuville 0:83cf97c10b63 118 int SDFileSystem::disk_initialize() {
geiineuville 0:83cf97c10b63 119
geiineuville 0:83cf97c10b63 120 _spi.frequency(100000); // Set to 100kHz for initialisation
geiineuville 0:83cf97c10b63 121
geiineuville 0:83cf97c10b63 122 // Initialise the card by clocking it a bit (cs = 1)
geiineuville 0:83cf97c10b63 123 _cs = 1;
geiineuville 0:83cf97c10b63 124 for(int i=0; i<16; i++) {
geiineuville 0:83cf97c10b63 125 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 126 }
geiineuville 0:83cf97c10b63 127
geiineuville 0:83cf97c10b63 128 // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
geiineuville 0:83cf97c10b63 129 if(_cmd(0, 0) != R1_IDLE_STATE) {
geiineuville 0:83cf97c10b63 130 fprintf(stderr, "No disk, or could not put SD card into SPI idle state" CR);
geiineuville 0:83cf97c10b63 131 return 1;
geiineuville 0:83cf97c10b63 132 }
geiineuville 0:83cf97c10b63 133
geiineuville 0:83cf97c10b63 134 int r = _cmd8();
geiineuville 0:83cf97c10b63 135 if(r == R1_IDLE_STATE) {
geiineuville 0:83cf97c10b63 136 printf("SD version 2.x" CR);
geiineuville 0:83cf97c10b63 137 } else if(r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
geiineuville 0:83cf97c10b63 138 printf("SD version 1.x" CR);
geiineuville 0:83cf97c10b63 139 } else {
geiineuville 0:83cf97c10b63 140 error("Unknown SD version" CR);
geiineuville 0:83cf97c10b63 141 }
geiineuville 0:83cf97c10b63 142
geiineuville 0:83cf97c10b63 143 // ACMD41 to give host capacity support (repeat until not busy)
geiineuville 0:83cf97c10b63 144 // ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand
geiineuville 0:83cf97c10b63 145 for(int i=0;; i++) {
geiineuville 0:83cf97c10b63 146 _cmd(55, 0);
geiineuville 0:83cf97c10b63 147 int response = _cmd(41, 0);
geiineuville 0:83cf97c10b63 148 if(response == 0) {
geiineuville 0:83cf97c10b63 149 break;
geiineuville 0:83cf97c10b63 150 } else if(i > SD_COMMAND_TIMEOUT) {
geiineuville 0:83cf97c10b63 151 fprintf(stderr, "Timeout waiting for card" CR);
geiineuville 0:83cf97c10b63 152 return 1;
geiineuville 0:83cf97c10b63 153 }
geiineuville 0:83cf97c10b63 154 }
geiineuville 0:83cf97c10b63 155
geiineuville 0:83cf97c10b63 156 // printf("OK" CR);
geiineuville 0:83cf97c10b63 157
geiineuville 0:83cf97c10b63 158 _sectors = _sd_sectors();
geiineuville 0:83cf97c10b63 159
geiineuville 0:83cf97c10b63 160 // Set block length to 512 (CMD16)
geiineuville 0:83cf97c10b63 161 if(_cmd(16, 512) != 0) {
geiineuville 0:83cf97c10b63 162 fprintf(stderr, "Set block timeout" CR);
geiineuville 0:83cf97c10b63 163 return 1;
geiineuville 0:83cf97c10b63 164 }
geiineuville 0:83cf97c10b63 165
geiineuville 0:83cf97c10b63 166 _spi.frequency(1000000); // Set to 1MHz for data transfer
geiineuville 0:83cf97c10b63 167 return 0;
geiineuville 0:83cf97c10b63 168 }
geiineuville 0:83cf97c10b63 169
geiineuville 0:83cf97c10b63 170 int SDFileSystem::disk_write(const char *buffer, int block_number) {
geiineuville 0:83cf97c10b63 171 // set write address for single block (CMD24)
geiineuville 0:83cf97c10b63 172 if(_cmd(24, block_number * 512) != 0) {
geiineuville 0:83cf97c10b63 173 return 1;
geiineuville 0:83cf97c10b63 174 }
geiineuville 0:83cf97c10b63 175
geiineuville 0:83cf97c10b63 176 // send the data block
geiineuville 0:83cf97c10b63 177 _write(buffer, 512);
geiineuville 0:83cf97c10b63 178 return 0;
geiineuville 0:83cf97c10b63 179 }
geiineuville 0:83cf97c10b63 180
geiineuville 0:83cf97c10b63 181 int SDFileSystem::disk_read(char *buffer, int block_number) {
geiineuville 0:83cf97c10b63 182 // set read address for single block (CMD17)
geiineuville 0:83cf97c10b63 183 if(_cmd(17, block_number * 512) != 0) {
geiineuville 0:83cf97c10b63 184 return 1;
geiineuville 0:83cf97c10b63 185 }
geiineuville 0:83cf97c10b63 186
geiineuville 0:83cf97c10b63 187 // receive the data
geiineuville 0:83cf97c10b63 188 _read(buffer, 512);
geiineuville 0:83cf97c10b63 189 return 0;
geiineuville 0:83cf97c10b63 190 }
geiineuville 0:83cf97c10b63 191
geiineuville 0:83cf97c10b63 192 int SDFileSystem::disk_status() { return 0; }
geiineuville 0:83cf97c10b63 193 int SDFileSystem::disk_sync() { return 0; }
geiineuville 0:83cf97c10b63 194 int SDFileSystem::disk_sectors() { return _sectors; }
geiineuville 0:83cf97c10b63 195
geiineuville 0:83cf97c10b63 196 // PRIVATE FUNCTIONS
geiineuville 0:83cf97c10b63 197
geiineuville 0:83cf97c10b63 198 int SDFileSystem::_cmd(int cmd, int arg) {
geiineuville 0:83cf97c10b63 199 _cs = 0;
geiineuville 0:83cf97c10b63 200
geiineuville 0:83cf97c10b63 201 // send a command
geiineuville 0:83cf97c10b63 202 _spi.write(0x40 | cmd);
geiineuville 0:83cf97c10b63 203 _spi.write(arg >> 24);
geiineuville 0:83cf97c10b63 204 _spi.write(arg >> 16);
geiineuville 0:83cf97c10b63 205 _spi.write(arg >> 8);
geiineuville 0:83cf97c10b63 206 _spi.write(arg >> 0);
geiineuville 0:83cf97c10b63 207 _spi.write(0x95);
geiineuville 0:83cf97c10b63 208
geiineuville 0:83cf97c10b63 209 // wait for the repsonse (response[7] == 0)
geiineuville 0:83cf97c10b63 210 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
geiineuville 0:83cf97c10b63 211 int response = _spi.write(0xFF);
geiineuville 0:83cf97c10b63 212 if(!(response & 0x80)) {
geiineuville 0:83cf97c10b63 213 _cs = 1;
geiineuville 0:83cf97c10b63 214 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 215 return response;
geiineuville 0:83cf97c10b63 216 }
geiineuville 0:83cf97c10b63 217 }
geiineuville 0:83cf97c10b63 218 _cs = 1;
geiineuville 0:83cf97c10b63 219 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 220 return -1; // timeout
geiineuville 0:83cf97c10b63 221 }
geiineuville 0:83cf97c10b63 222
geiineuville 0:83cf97c10b63 223 int SDFileSystem::_cmd8() {
geiineuville 0:83cf97c10b63 224 _cs = 0;
geiineuville 0:83cf97c10b63 225
geiineuville 0:83cf97c10b63 226 // send a command
geiineuville 0:83cf97c10b63 227 _spi.write(0x40 | 8); // CMD8
geiineuville 0:83cf97c10b63 228 _spi.write(0x00); // reserved
geiineuville 0:83cf97c10b63 229 _spi.write(0x00); // reserved
geiineuville 0:83cf97c10b63 230 _spi.write(0x01); // 3.3v
geiineuville 0:83cf97c10b63 231 _spi.write(0xAA); // check pattern
geiineuville 0:83cf97c10b63 232 _spi.write(0x87); // crc
geiineuville 0:83cf97c10b63 233
geiineuville 0:83cf97c10b63 234 // wait for the repsonse (response[7] == 0)
geiineuville 0:83cf97c10b63 235 for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
geiineuville 0:83cf97c10b63 236 char response[5];
geiineuville 0:83cf97c10b63 237 response[0] = _spi.write(0xFF);
geiineuville 0:83cf97c10b63 238 if(!(response[0] & 0x80)) {
geiineuville 0:83cf97c10b63 239 for(int j=1; j<5; j++) {
geiineuville 0:83cf97c10b63 240 response[i] = _spi.write(0xFF);
geiineuville 0:83cf97c10b63 241 }
geiineuville 0:83cf97c10b63 242 _cs = 1;
geiineuville 0:83cf97c10b63 243 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 244 return response[0];
geiineuville 0:83cf97c10b63 245 }
geiineuville 0:83cf97c10b63 246 }
geiineuville 0:83cf97c10b63 247 _cs = 1;
geiineuville 0:83cf97c10b63 248 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 249 return -1; // timeout
geiineuville 0:83cf97c10b63 250 }
geiineuville 0:83cf97c10b63 251
geiineuville 0:83cf97c10b63 252 int SDFileSystem::_read(char *buffer, int length) {
geiineuville 0:83cf97c10b63 253 _cs = 0;
geiineuville 0:83cf97c10b63 254
geiineuville 0:83cf97c10b63 255 // read until start byte (0xFF)
geiineuville 0:83cf97c10b63 256 while(_spi.write(0xFF) != 0xFE);
geiineuville 0:83cf97c10b63 257
geiineuville 0:83cf97c10b63 258 // read data
geiineuville 0:83cf97c10b63 259 for(int i=0; i<length; i++) {
geiineuville 0:83cf97c10b63 260 buffer[i] = _spi.write(0xFF);
geiineuville 0:83cf97c10b63 261 }
geiineuville 0:83cf97c10b63 262 _spi.write(0xFF); // checksum
geiineuville 0:83cf97c10b63 263 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 264
geiineuville 0:83cf97c10b63 265 _cs = 1;
geiineuville 0:83cf97c10b63 266 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 267 return 0;
geiineuville 0:83cf97c10b63 268 }
geiineuville 0:83cf97c10b63 269
geiineuville 0:83cf97c10b63 270 int SDFileSystem::_write(const char *buffer, int length) {
geiineuville 0:83cf97c10b63 271 _cs = 0;
geiineuville 0:83cf97c10b63 272
geiineuville 0:83cf97c10b63 273 // indicate start of block
geiineuville 0:83cf97c10b63 274 _spi.write(0xFE);
geiineuville 0:83cf97c10b63 275
geiineuville 0:83cf97c10b63 276 // write the data
geiineuville 0:83cf97c10b63 277 for(int i=0; i<length; i++) {
geiineuville 0:83cf97c10b63 278 _spi.write(buffer[i]);
geiineuville 0:83cf97c10b63 279 }
geiineuville 0:83cf97c10b63 280
geiineuville 0:83cf97c10b63 281 // write the checksum
geiineuville 0:83cf97c10b63 282 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 283 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 284
geiineuville 0:83cf97c10b63 285 // check the repsonse token
geiineuville 0:83cf97c10b63 286 if((_spi.write(0xFF) & 0x1F) != 0x05) {
geiineuville 0:83cf97c10b63 287 _cs = 1;
geiineuville 0:83cf97c10b63 288 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 289 return 1;
geiineuville 0:83cf97c10b63 290 }
geiineuville 0:83cf97c10b63 291
geiineuville 0:83cf97c10b63 292 // wait for write to finish
geiineuville 0:83cf97c10b63 293 while(_spi.write(0xFF) == 0);
geiineuville 0:83cf97c10b63 294
geiineuville 0:83cf97c10b63 295 _cs = 1;
geiineuville 0:83cf97c10b63 296 _spi.write(0xFF);
geiineuville 0:83cf97c10b63 297 return 0;
geiineuville 0:83cf97c10b63 298 }
geiineuville 0:83cf97c10b63 299
geiineuville 0:83cf97c10b63 300 static int ext_bits(char *data, int msb, int lsb) {
geiineuville 0:83cf97c10b63 301 int bits = 0;
geiineuville 0:83cf97c10b63 302 int size = 1 + msb - lsb;
geiineuville 0:83cf97c10b63 303 for(int i=0; i<size; i++) {
geiineuville 0:83cf97c10b63 304 int position = lsb + i;
geiineuville 0:83cf97c10b63 305 int byte = 15 - (position >> 3);
geiineuville 0:83cf97c10b63 306 int bit = position & 0x7;
geiineuville 0:83cf97c10b63 307 int value = (data[byte] >> bit) & 1;
geiineuville 0:83cf97c10b63 308 bits |= value << i;
geiineuville 0:83cf97c10b63 309 }
geiineuville 0:83cf97c10b63 310 return bits;
geiineuville 0:83cf97c10b63 311 }
geiineuville 0:83cf97c10b63 312
geiineuville 0:83cf97c10b63 313 int SDFileSystem::_sd_sectors() {
geiineuville 0:83cf97c10b63 314
geiineuville 0:83cf97c10b63 315 // CMD9, Response R2 (R1 byte + 16-byte block read)
geiineuville 0:83cf97c10b63 316 if(_cmd(9, 0) != 0) {
geiineuville 0:83cf97c10b63 317 fprintf(stderr, "Didn't get a response from the disk" CR);
geiineuville 0:83cf97c10b63 318 return 0;
geiineuville 0:83cf97c10b63 319 }
geiineuville 0:83cf97c10b63 320
geiineuville 0:83cf97c10b63 321 char csd[16];
geiineuville 0:83cf97c10b63 322 if(_read(csd, 16) != 0) {
geiineuville 0:83cf97c10b63 323 fprintf(stderr, "Couldn't read csd response from disk" CR);
geiineuville 0:83cf97c10b63 324 return 0;
geiineuville 0:83cf97c10b63 325 }
geiineuville 0:83cf97c10b63 326
geiineuville 0:83cf97c10b63 327 // csd_structure : csd[127:126]
geiineuville 0:83cf97c10b63 328 // c_size : csd[73:62]
geiineuville 0:83cf97c10b63 329 // c_size_mult : csd[49:47]
geiineuville 0:83cf97c10b63 330 // read_bl_len : csd[83:80]
geiineuville 0:83cf97c10b63 331
geiineuville 0:83cf97c10b63 332 int csd_structure = ext_bits(csd, 127, 126);
geiineuville 0:83cf97c10b63 333 int c_size = ext_bits(csd, 73, 62);
geiineuville 0:83cf97c10b63 334 int c_size_mult = ext_bits(csd, 49, 47);
geiineuville 0:83cf97c10b63 335 int read_bl_len = ext_bits(csd, 83, 80);
geiineuville 0:83cf97c10b63 336
geiineuville 0:83cf97c10b63 337 if(csd_structure != 0) {
geiineuville 0:83cf97c10b63 338 fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures" CR);
geiineuville 0:83cf97c10b63 339 // Non-zero is SDHC.
geiineuville 0:83cf97c10b63 340 return 0;
geiineuville 0:83cf97c10b63 341 }
geiineuville 0:83cf97c10b63 342
geiineuville 0:83cf97c10b63 343 int blocks = (c_size + 1) * (1 << (c_size_mult + 2));
geiineuville 0:83cf97c10b63 344 int block_size = 1 << read_bl_len;
geiineuville 0:83cf97c10b63 345
geiineuville 0:83cf97c10b63 346 if (block_size != 512 && block_size != 1024) {
geiineuville 0:83cf97c10b63 347 fprintf(stderr, "This disk tastes funny! %d byte block. I only like 512 or 1024 -byte blocks" CR, block_size);
geiineuville 0:83cf97c10b63 348 return 0;
geiineuville 0:83cf97c10b63 349 }
geiineuville 0:83cf97c10b63 350
geiineuville 0:83cf97c10b63 351 return blocks;
geiineuville 0:83cf97c10b63 352 }