guru sath / Mbed 2 deprecated USBTOUSB

Pendrive to sd card data transfer coding

Dependencies:   FatFileSystem TextLCD mbed

Fork of MSCUsbHost by gavin beardall

SDFileSystem.cpp@1:77e50c06ea01, 2015-04-16 (annotated)

Committer:
sathguru
Date:
Thu Apr 16 05:12:20 2015 +0000
Revision:
1:77e50c06ea01
Pendrive to sd card data transfer coding

Who changed what in which revision?

UserRevisionLine numberNew contents of line
sathguru 1:77e50c06ea01 1 /* mbed Microcontroller Library - SDFileSystem
sathguru 1:77e50c06ea01 2 * Copyright (c) 2008-2009, sford
sathguru 1:77e50c06ea01 3 */
sathguru 1:77e50c06ea01 4
sathguru 1:77e50c06ea01 5 // VERY DRAFT CODE! Needs serious rework/refactoring
sathguru 1:77e50c06ea01 6
sathguru 1:77e50c06ea01 7 /* Introduction
sathguru 1:77e50c06ea01 8 * ------------
sathguru 1:77e50c06ea01 9 * SD and MMC cards support a number of interfaces, but common to them all
sathguru 1:77e50c06ea01 10 * is one based on SPI. This is the one I'm implmenting because it means
sathguru 1:77e50c06ea01 11 * it is much more portable even though not so performant, and we already
sathguru 1:77e50c06ea01 12 * have the mbed SPI Interface!
sathguru 1:77e50c06ea01 13 *
sathguru 1:77e50c06ea01 14 * The main reference I'm using is Chapter 7, "SPI Mode" of:
sathguru 1:77e50c06ea01 15 * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
sathguru 1:77e50c06ea01 16 *
sathguru 1:77e50c06ea01 17 * SPI Startup
sathguru 1:77e50c06ea01 18 * -----------
sathguru 1:77e50c06ea01 19 * The SD card powers up in SD mode. The SPI interface mode is selected by
sathguru 1:77e50c06ea01 20 * asserting CS low and sending the reset command (CMD0). The card will
sathguru 1:77e50c06ea01 21 * respond with a (R1) response.
sathguru 1:77e50c06ea01 22 *
sathguru 1:77e50c06ea01 23 * CMD8 is optionally sent to determine the voltage range supported, and
sathguru 1:77e50c06ea01 24 * indirectly determine whether it is a version 1.x SD/non-SD card or
sathguru 1:77e50c06ea01 25 * version 2.x. I'll just ignore this for now.
sathguru 1:77e50c06ea01 26 *
sathguru 1:77e50c06ea01 27 * ACMD41 is repeatedly issued to initialise the card, until "in idle"
sathguru 1:77e50c06ea01 28 * (bit 0) of the R1 response goes to '0', indicating it is initialised.
sathguru 1:77e50c06ea01 29 *
sathguru 1:77e50c06ea01 30 * You should also indicate whether the host supports High Capicity cards,
sathguru 1:77e50c06ea01 31 * and check whether the card is high capacity - i'll also ignore this
sathguru 1:77e50c06ea01 32 *
sathguru 1:77e50c06ea01 33 * SPI Protocol
sathguru 1:77e50c06ea01 34 * ------------
sathguru 1:77e50c06ea01 35 * The SD SPI protocol is based on transactions made up of 8-bit words, with
sathguru 1:77e50c06ea01 36 * the host starting every bus transaction by asserting the CS signal low. The
sathguru 1:77e50c06ea01 37 * card always responds to commands, data blocks and errors.
sathguru 1:77e50c06ea01 38 *
sathguru 1:77e50c06ea01 39 * The protocol supports a CRC, but by default it is off (except for the
sathguru 1:77e50c06ea01 40 * first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
sathguru 1:77e50c06ea01 41 * I'll leave the CRC off I think!
sathguru 1:77e50c06ea01 42 *
sathguru 1:77e50c06ea01 43 * Standard capacity cards have variable data block sizes, whereas High
sathguru 1:77e50c06ea01 44 * Capacity cards fix the size of data block to 512 bytes. I'll therefore
sathguru 1:77e50c06ea01 45 * just always use the Standard Capacity cards with a block size of 512 bytes.
sathguru 1:77e50c06ea01 46 * This is set with CMD16.
sathguru 1:77e50c06ea01 47 *
sathguru 1:77e50c06ea01 48 * You can read and write single blocks (CMD17, CMD25) or multiple blocks
sathguru 1:77e50c06ea01 49 * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
sathguru 1:77e50c06ea01 50 * the card gets a read command, it responds with a response token, and then
sathguru 1:77e50c06ea01 51 * a data token or an error.
sathguru 1:77e50c06ea01 52 *
sathguru 1:77e50c06ea01 53 * SPI Command Format
sathguru 1:77e50c06ea01 54 * ------------------
sathguru 1:77e50c06ea01 55 * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
sathguru 1:77e50c06ea01 56 *
sathguru 1:77e50c06ea01 57 * +---------------+------------+------------+-----------+----------+--------------+
sathguru 1:77e50c06ea01 58 * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
sathguru 1:77e50c06ea01 59 * +---------------+------------+------------+-----------+----------+--------------+
sathguru 1:77e50c06ea01 60 *
sathguru 1:77e50c06ea01 61 * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
sathguru 1:77e50c06ea01 62 *
sathguru 1:77e50c06ea01 63 * All Application Specific commands shall be preceded with APP_CMD (CMD55).
sathguru 1:77e50c06ea01 64 *
sathguru 1:77e50c06ea01 65 * SPI Response Format
sathguru 1:77e50c06ea01 66 * -------------------
sathguru 1:77e50c06ea01 67 * The main response format (R1) is a status byte (normally zero). Key flags:
sathguru 1:77e50c06ea01 68 * idle - 1 if the card is in an idle state/initialising
sathguru 1:77e50c06ea01 69 * cmd - 1 if an illegal command code was detected
sathguru 1:77e50c06ea01 70 *
sathguru 1:77e50c06ea01 71 * +-------------------------------------------------+
sathguru 1:77e50c06ea01 72 * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
sathguru 1:77e50c06ea01 73 * +-------------------------------------------------+
sathguru 1:77e50c06ea01 74 *
sathguru 1:77e50c06ea01 75 * R1b is the same, except it is followed by a busy signal (zeros) until
sathguru 1:77e50c06ea01 76 * the first non-zero byte when it is ready again.
sathguru 1:77e50c06ea01 77 *
sathguru 1:77e50c06ea01 78 * Data Response Token
sathguru 1:77e50c06ea01 79 * -------------------
sathguru 1:77e50c06ea01 80 * Every data block written to the card is acknowledged by a byte
sathguru 1:77e50c06ea01 81 * response token
sathguru 1:77e50c06ea01 82 *
sathguru 1:77e50c06ea01 83 * +----------------------+
sathguru 1:77e50c06ea01 84 * | xxx | 0 | status | 1 |
sathguru 1:77e50c06ea01 85 * +----------------------+
sathguru 1:77e50c06ea01 86 * 010 - OK!
sathguru 1:77e50c06ea01 87 * 101 - CRC Error
sathguru 1:77e50c06ea01 88 * 110 - Write Error
sathguru 1:77e50c06ea01 89 *
sathguru 1:77e50c06ea01 90 * Single Block Read and Write
sathguru 1:77e50c06ea01 91 * ---------------------------
sathguru 1:77e50c06ea01 92 *
sathguru 1:77e50c06ea01 93 * Block transfers have a byte header, followed by the data, followed
sathguru 1:77e50c06ea01 94 * by a 16-bit CRC. In our case, the data will always be 512 bytes.
sathguru 1:77e50c06ea01 95 *
sathguru 1:77e50c06ea01 96 * +------+---------+---------+- - - -+---------+-----------+----------+
sathguru 1:77e50c06ea01 97 * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] |
sathguru 1:77e50c06ea01 98 * +------+---------+---------+- - - -+---------+-----------+----------+
sathguru 1:77e50c06ea01 99 */
sathguru 1:77e50c06ea01 100
sathguru 1:77e50c06ea01 101 #include "SDFileSystem.h"
sathguru 1:77e50c06ea01 102
sathguru 1:77e50c06ea01 103 #define SD_COMMAND_TIMEOUT 5000
sathguru 1:77e50c06ea01 104
sathguru 1:77e50c06ea01 105 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
sathguru 1:77e50c06ea01 106 FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) {
sathguru 1:77e50c06ea01 107 _cs = 1;
sathguru 1:77e50c06ea01 108 }
sathguru 1:77e50c06ea01 109
sathguru 1:77e50c06ea01 110 #define R1_IDLE_STATE (1 << 0)
sathguru 1:77e50c06ea01 111 #define R1_ERASE_RESET (1 << 1)
sathguru 1:77e50c06ea01 112 #define R1_ILLEGAL_COMMAND (1 << 2)
sathguru 1:77e50c06ea01 113 #define R1_COM_CRC_ERROR (1 << 3)
sathguru 1:77e50c06ea01 114 #define R1_ERASE_SEQUENCE_ERROR (1 << 4)
sathguru 1:77e50c06ea01 115 #define R1_ADDRESS_ERROR (1 << 5)
sathguru 1:77e50c06ea01 116 #define R1_PARAMETER_ERROR (1 << 6)
sathguru 1:77e50c06ea01 117
sathguru 1:77e50c06ea01 118 // Types
sathguru 1:77e50c06ea01 119 // - v1.x Standard Capacity
sathguru 1:77e50c06ea01 120 // - v2.x Standard Capacity
sathguru 1:77e50c06ea01 121 // - v2.x High Capacity
sathguru 1:77e50c06ea01 122 // - Not recognised as an SD Card
sathguru 1:77e50c06ea01 123
sathguru 1:77e50c06ea01 124 #define SDCARD_FAIL 0
sathguru 1:77e50c06ea01 125 #define SDCARD_V1 1
sathguru 1:77e50c06ea01 126 #define SDCARD_V2 2
sathguru 1:77e50c06ea01 127 #define SDCARD_V2HC 3
sathguru 1:77e50c06ea01 128
sathguru 1:77e50c06ea01 129 int SDFileSystem::initialise_card() {
sathguru 1:77e50c06ea01 130 // Set to 100kHz for initialisation, and clock card with cs = 1
sathguru 1:77e50c06ea01 131 _spi.frequency(100000);
sathguru 1:77e50c06ea01 132 _cs = 1;
sathguru 1:77e50c06ea01 133 for(int i=0; i<16; i++) {
sathguru 1:77e50c06ea01 134 _spi.write(0xFF);
sathguru 1:77e50c06ea01 135 }
sathguru 1:77e50c06ea01 136
sathguru 1:77e50c06ea01 137 // send CMD0, should return with all zeros except IDLE STATE set (bit 0)
sathguru 1:77e50c06ea01 138 if(_cmd(0, 0) != R1_IDLE_STATE) {
sathguru 1:77e50c06ea01 139 fprintf(stderr, "No disk, or could not put SD card in to SPI idle state\n");
sathguru 1:77e50c06ea01 140 return SDCARD_FAIL;
sathguru 1:77e50c06ea01 141 }
sathguru 1:77e50c06ea01 142
sathguru 1:77e50c06ea01 143 // send CMD8 to determine whther it is ver 2.x
sathguru 1:77e50c06ea01 144 int r = _cmd8();
sathguru 1:77e50c06ea01 145 if(r == R1_IDLE_STATE) {
sathguru 1:77e50c06ea01 146 return initialise_card_v2();
sathguru 1:77e50c06ea01 147 } else if(r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
sathguru 1:77e50c06ea01 148 return initialise_card_v1();
sathguru 1:77e50c06ea01 149 } else {
sathguru 1:77e50c06ea01 150 fprintf(stderr, "Not in idle state after sending CMD8 (not an SD card?)\n");
sathguru 1:77e50c06ea01 151 return SDCARD_FAIL;
sathguru 1:77e50c06ea01 152 }
sathguru 1:77e50c06ea01 153 }
sathguru 1:77e50c06ea01 154
sathguru 1:77e50c06ea01 155 int SDFileSystem::initialise_card_v1() {
sathguru 1:77e50c06ea01 156 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
sathguru 1:77e50c06ea01 157 _cmd(55, 0);
sathguru 1:77e50c06ea01 158 if(_cmd(41, 0) == 0) {
sathguru 1:77e50c06ea01 159 return SDCARD_V1;
sathguru 1:77e50c06ea01 160 }
sathguru 1:77e50c06ea01 161 }
sathguru 1:77e50c06ea01 162
sathguru 1:77e50c06ea01 163 fprintf(stderr, "Timeout waiting for v1.x card\n");
sathguru 1:77e50c06ea01 164 return SDCARD_FAIL;
sathguru 1:77e50c06ea01 165 }
sathguru 1:77e50c06ea01 166
sathguru 1:77e50c06ea01 167 int SDFileSystem::initialise_card_v2() {
sathguru 1:77e50c06ea01 168
sathguru 1:77e50c06ea01 169 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
sathguru 1:77e50c06ea01 170 _cmd(55, 0);
sathguru 1:77e50c06ea01 171 if(_cmd(41, 0) == 0) {
sathguru 1:77e50c06ea01 172 _cmd58();
sathguru 1:77e50c06ea01 173 return SDCARD_V2;
sathguru 1:77e50c06ea01 174 }
sathguru 1:77e50c06ea01 175 }
sathguru 1:77e50c06ea01 176
sathguru 1:77e50c06ea01 177 fprintf(stderr, "Timeout waiting for v2.x card\n");
sathguru 1:77e50c06ea01 178 return SDCARD_FAIL;
sathguru 1:77e50c06ea01 179 }
sathguru 1:77e50c06ea01 180
sathguru 1:77e50c06ea01 181 int SDFileSystem::disk_initialize() {
sathguru 1:77e50c06ea01 182
sathguru 1:77e50c06ea01 183 int i = initialise_card();
sathguru 1:77e50c06ea01 184 // printf("init card = %d\n", i);
sathguru 1:77e50c06ea01 185 // printf("OK\n");
sathguru 1:77e50c06ea01 186
sathguru 1:77e50c06ea01 187 _sectors = _sd_sectors();
sathguru 1:77e50c06ea01 188
sathguru 1:77e50c06ea01 189 // Set block length to 512 (CMD16)
sathguru 1:77e50c06ea01 190 if(_cmd(16, 512) != 0) {
sathguru 1:77e50c06ea01 191 fprintf(stderr, "Set 512-byte block timed out\n");
sathguru 1:77e50c06ea01 192 return 1;
sathguru 1:77e50c06ea01 193 }
sathguru 1:77e50c06ea01 194
sathguru 1:77e50c06ea01 195 _spi.frequency(1000000); // Set to 1MHz for data transfer
sathguru 1:77e50c06ea01 196 return 0;
sathguru 1:77e50c06ea01 197 }
sathguru 1:77e50c06ea01 198
sathguru 1:77e50c06ea01 199 int SDFileSystem::disk_write(const char *buffer, int block_number) {
sathguru 1:77e50c06ea01 200 // set write address for single block (CMD24)
sathguru 1:77e50c06ea01 201 if(_cmd(24, block_number * 512) != 0) {
sathguru 1:77e50c06ea01 202 return 1;
sathguru 1:77e50c06ea01 203 }
sathguru 1:77e50c06ea01 204
sathguru 1:77e50c06ea01 205 // send the data block
sathguru 1:77e50c06ea01 206 _write(buffer, 512);
sathguru 1:77e50c06ea01 207 return 0;
sathguru 1:77e50c06ea01 208 }
sathguru 1:77e50c06ea01 209
sathguru 1:77e50c06ea01 210 int SDFileSystem::disk_read(char *buffer, int block_number) {
sathguru 1:77e50c06ea01 211 // set read address for single block (CMD17)
sathguru 1:77e50c06ea01 212 if(_cmd(17, block_number * 512) != 0) {
sathguru 1:77e50c06ea01 213 return 1;
sathguru 1:77e50c06ea01 214 }
sathguru 1:77e50c06ea01 215
sathguru 1:77e50c06ea01 216 // receive the data
sathguru 1:77e50c06ea01 217 _read(buffer, 512);
sathguru 1:77e50c06ea01 218 return 0;
sathguru 1:77e50c06ea01 219 }
sathguru 1:77e50c06ea01 220
sathguru 1:77e50c06ea01 221 int SDFileSystem::disk_status() { return 0; }
sathguru 1:77e50c06ea01 222 int SDFileSystem::disk_sync() { return 0; }
sathguru 1:77e50c06ea01 223 int SDFileSystem::disk_sectors() { return _sectors; }
sathguru 1:77e50c06ea01 224
sathguru 1:77e50c06ea01 225 // PRIVATE FUNCTIONS
sathguru 1:77e50c06ea01 226
sathguru 1:77e50c06ea01 227 int SDFileSystem::_cmd(int cmd, int arg) {
sathguru 1:77e50c06ea01 228 _cs = 0;
sathguru 1:77e50c06ea01 229
sathguru 1:77e50c06ea01 230 // send a command
sathguru 1:77e50c06ea01 231 _spi.write(0x40 | cmd);
sathguru 1:77e50c06ea01 232 _spi.write(arg >> 24);
sathguru 1:77e50c06ea01 233 _spi.write(arg >> 16);
sathguru 1:77e50c06ea01 234 _spi.write(arg >> 8);
sathguru 1:77e50c06ea01 235 _spi.write(arg >> 0);
sathguru 1:77e50c06ea01 236 _spi.write(0x95);
sathguru 1:77e50c06ea01 237
sathguru 1:77e50c06ea01 238 // wait for the repsonse (response[7] == 0)
sathguru 1:77e50c06ea01 239 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
sathguru 1:77e50c06ea01 240 int response = _spi.write(0xFF);
sathguru 1:77e50c06ea01 241 if(!(response & 0x80)) {
sathguru 1:77e50c06ea01 242 _cs = 1;
sathguru 1:77e50c06ea01 243 _spi.write(0xFF);
sathguru 1:77e50c06ea01 244 return response;
sathguru 1:77e50c06ea01 245 }
sathguru 1:77e50c06ea01 246 }
sathguru 1:77e50c06ea01 247 _cs = 1;
sathguru 1:77e50c06ea01 248 _spi.write(0xFF);
sathguru 1:77e50c06ea01 249 return -1; // timeout
sathguru 1:77e50c06ea01 250 }
sathguru 1:77e50c06ea01 251 int SDFileSystem::_cmdx(int cmd, int arg) {
sathguru 1:77e50c06ea01 252 _cs = 0;
sathguru 1:77e50c06ea01 253
sathguru 1:77e50c06ea01 254 // send a command
sathguru 1:77e50c06ea01 255 _spi.write(0x40 | cmd);
sathguru 1:77e50c06ea01 256 _spi.write(arg >> 24);
sathguru 1:77e50c06ea01 257 _spi.write(arg >> 16);
sathguru 1:77e50c06ea01 258 _spi.write(arg >> 8);
sathguru 1:77e50c06ea01 259 _spi.write(arg >> 0);
sathguru 1:77e50c06ea01 260 _spi.write(0x95);
sathguru 1:77e50c06ea01 261
sathguru 1:77e50c06ea01 262 // wait for the repsonse (response[7] == 0)
sathguru 1:77e50c06ea01 263 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
sathguru 1:77e50c06ea01 264 int response = _spi.write(0xFF);
sathguru 1:77e50c06ea01 265 if(!(response & 0x80)) {
sathguru 1:77e50c06ea01 266 return response;
sathguru 1:77e50c06ea01 267 }
sathguru 1:77e50c06ea01 268 }
sathguru 1:77e50c06ea01 269 _cs = 1;
sathguru 1:77e50c06ea01 270 _spi.write(0xFF);
sathguru 1:77e50c06ea01 271 return -1; // timeout
sathguru 1:77e50c06ea01 272 }
sathguru 1:77e50c06ea01 273
sathguru 1:77e50c06ea01 274
sathguru 1:77e50c06ea01 275 int SDFileSystem::_cmd58() {
sathguru 1:77e50c06ea01 276 _cs = 0;
sathguru 1:77e50c06ea01 277 int arg = 0;
sathguru 1:77e50c06ea01 278
sathguru 1:77e50c06ea01 279 // send a command
sathguru 1:77e50c06ea01 280 _spi.write(0x40 | 58);
sathguru 1:77e50c06ea01 281 _spi.write(arg >> 24);
sathguru 1:77e50c06ea01 282 _spi.write(arg >> 16);
sathguru 1:77e50c06ea01 283 _spi.write(arg >> 8);
sathguru 1:77e50c06ea01 284 _spi.write(arg >> 0);
sathguru 1:77e50c06ea01 285 _spi.write(0x95);
sathguru 1:77e50c06ea01 286
sathguru 1:77e50c06ea01 287 // wait for the repsonse (response[7] == 0)
sathguru 1:77e50c06ea01 288 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) {
sathguru 1:77e50c06ea01 289 int response = _spi.write(0xFF);
sathguru 1:77e50c06ea01 290 if(!(response & 0x80)) {
sathguru 1:77e50c06ea01 291 int ocr = _spi.write(0xFF) << 24;
sathguru 1:77e50c06ea01 292 ocr |= _spi.write(0xFF) << 16;
sathguru 1:77e50c06ea01 293 ocr |= _spi.write(0xFF) << 8;
sathguru 1:77e50c06ea01 294 ocr |= _spi.write(0xFF) << 0;
sathguru 1:77e50c06ea01 295 // printf("OCR = 0x%08X\n", ocr);
sathguru 1:77e50c06ea01 296 _cs = 1;
sathguru 1:77e50c06ea01 297 _spi.write(0xFF);
sathguru 1:77e50c06ea01 298 return response;
sathguru 1:77e50c06ea01 299 }
sathguru 1:77e50c06ea01 300 }
sathguru 1:77e50c06ea01 301 _cs = 1;
sathguru 1:77e50c06ea01 302 _spi.write(0xFF);
sathguru 1:77e50c06ea01 303 return -1; // timeout
sathguru 1:77e50c06ea01 304 }
sathguru 1:77e50c06ea01 305
sathguru 1:77e50c06ea01 306 int SDFileSystem::_cmd8() {
sathguru 1:77e50c06ea01 307 _cs = 0;
sathguru 1:77e50c06ea01 308
sathguru 1:77e50c06ea01 309 // send a command
sathguru 1:77e50c06ea01 310 _spi.write(0x40 | 8); // CMD8
sathguru 1:77e50c06ea01 311 _spi.write(0x00); // reserved
sathguru 1:77e50c06ea01 312 _spi.write(0x00); // reserved
sathguru 1:77e50c06ea01 313 _spi.write(0x01); // 3.3v
sathguru 1:77e50c06ea01 314 _spi.write(0xAA); // check pattern
sathguru 1:77e50c06ea01 315 _spi.write(0x87); // crc
sathguru 1:77e50c06ea01 316
sathguru 1:77e50c06ea01 317 // wait for the repsonse (response[7] == 0)
sathguru 1:77e50c06ea01 318 for(int i=0; i<SD_COMMAND_TIMEOUT * 1000; i++) {
sathguru 1:77e50c06ea01 319 char response[5];
sathguru 1:77e50c06ea01 320 response[0] = _spi.write(0xFF);
sathguru 1:77e50c06ea01 321 if(!(response[0] & 0x80)) {
sathguru 1:77e50c06ea01 322 for(int j=1; j<5; j++) {
sathguru 1:77e50c06ea01 323 response[i] = _spi.write(0xFF);
sathguru 1:77e50c06ea01 324 }
sathguru 1:77e50c06ea01 325 _cs = 1;
sathguru 1:77e50c06ea01 326 _spi.write(0xFF);
sathguru 1:77e50c06ea01 327 return response[0];
sathguru 1:77e50c06ea01 328 }
sathguru 1:77e50c06ea01 329 }
sathguru 1:77e50c06ea01 330 _cs = 1;
sathguru 1:77e50c06ea01 331 _spi.write(0xFF);
sathguru 1:77e50c06ea01 332 return -1; // timeout
sathguru 1:77e50c06ea01 333 }
sathguru 1:77e50c06ea01 334
sathguru 1:77e50c06ea01 335 int SDFileSystem::_read(char *buffer, int length) {
sathguru 1:77e50c06ea01 336 _cs = 0;
sathguru 1:77e50c06ea01 337
sathguru 1:77e50c06ea01 338 // read until start byte (0xFF)
sathguru 1:77e50c06ea01 339 while(_spi.write(0xFF) != 0xFE);
sathguru 1:77e50c06ea01 340
sathguru 1:77e50c06ea01 341 // read data
sathguru 1:77e50c06ea01 342 for(int i=0; i<length; i++) {
sathguru 1:77e50c06ea01 343 buffer[i] = _spi.write(0xFF);
sathguru 1:77e50c06ea01 344 }
sathguru 1:77e50c06ea01 345 _spi.write(0xFF); // checksum
sathguru 1:77e50c06ea01 346 _spi.write(0xFF);
sathguru 1:77e50c06ea01 347
sathguru 1:77e50c06ea01 348 _cs = 1;
sathguru 1:77e50c06ea01 349 _spi.write(0xFF);
sathguru 1:77e50c06ea01 350 return 0;
sathguru 1:77e50c06ea01 351 }
sathguru 1:77e50c06ea01 352
sathguru 1:77e50c06ea01 353 int SDFileSystem::_write(const char *buffer, int length) {
sathguru 1:77e50c06ea01 354 _cs = 0;
sathguru 1:77e50c06ea01 355
sathguru 1:77e50c06ea01 356 // indicate start of block
sathguru 1:77e50c06ea01 357 _spi.write(0xFE);
sathguru 1:77e50c06ea01 358
sathguru 1:77e50c06ea01 359 // write the data
sathguru 1:77e50c06ea01 360 for(int i=0; i<length; i++) {
sathguru 1:77e50c06ea01 361 _spi.write(buffer[i]);
sathguru 1:77e50c06ea01 362 }
sathguru 1:77e50c06ea01 363
sathguru 1:77e50c06ea01 364 // write the checksum
sathguru 1:77e50c06ea01 365 _spi.write(0xFF);
sathguru 1:77e50c06ea01 366 _spi.write(0xFF);
sathguru 1:77e50c06ea01 367
sathguru 1:77e50c06ea01 368 // check the repsonse token
sathguru 1:77e50c06ea01 369 if((_spi.write(0xFF) & 0x1F) != 0x05) {
sathguru 1:77e50c06ea01 370 _cs = 1;
sathguru 1:77e50c06ea01 371 _spi.write(0xFF);
sathguru 1:77e50c06ea01 372 return 1;
sathguru 1:77e50c06ea01 373 }
sathguru 1:77e50c06ea01 374
sathguru 1:77e50c06ea01 375 // wait for write to finish
sathguru 1:77e50c06ea01 376 while(_spi.write(0xFF) == 0);
sathguru 1:77e50c06ea01 377
sathguru 1:77e50c06ea01 378 _cs = 1;
sathguru 1:77e50c06ea01 379 _spi.write(0xFF);
sathguru 1:77e50c06ea01 380 return 0;
sathguru 1:77e50c06ea01 381 }
sathguru 1:77e50c06ea01 382
sathguru 1:77e50c06ea01 383 static int ext_bits(char *data, int msb, int lsb) {
sathguru 1:77e50c06ea01 384 int bits = 0;
sathguru 1:77e50c06ea01 385 int size = 1 + msb - lsb;
sathguru 1:77e50c06ea01 386 for(int i=0; i<size; i++) {
sathguru 1:77e50c06ea01 387 int position = lsb + i;
sathguru 1:77e50c06ea01 388 int byte = 15 - (position >> 3);
sathguru 1:77e50c06ea01 389 int bit = position & 0x7;
sathguru 1:77e50c06ea01 390 int value = (data[byte] >> bit) & 1;
sathguru 1:77e50c06ea01 391 bits |= value << i;
sathguru 1:77e50c06ea01 392 }
sathguru 1:77e50c06ea01 393 return bits;
sathguru 1:77e50c06ea01 394 }
sathguru 1:77e50c06ea01 395
sathguru 1:77e50c06ea01 396 int SDFileSystem::_sd_sectors() {
sathguru 1:77e50c06ea01 397
sathguru 1:77e50c06ea01 398 // CMD9, Response R2 (R1 byte + 16-byte block read)
sathguru 1:77e50c06ea01 399 if(_cmdx(9, 0) != 0) {
sathguru 1:77e50c06ea01 400 fprintf(stderr, "Didn't get a response from the disk\n");
sathguru 1:77e50c06ea01 401 return 0;
sathguru 1:77e50c06ea01 402 }
sathguru 1:77e50c06ea01 403
sathguru 1:77e50c06ea01 404 char csd[16];
sathguru 1:77e50c06ea01 405 if(_read(csd, 16) != 0) {
sathguru 1:77e50c06ea01 406 fprintf(stderr, "Couldn't read csd response from disk\n");
sathguru 1:77e50c06ea01 407 return 0;
sathguru 1:77e50c06ea01 408 }
sathguru 1:77e50c06ea01 409
sathguru 1:77e50c06ea01 410 // csd_structure : csd[127:126]
sathguru 1:77e50c06ea01 411 // c_size : csd[73:62]
sathguru 1:77e50c06ea01 412 // c_size_mult : csd[49:47]
sathguru 1:77e50c06ea01 413 // read_bl_len : csd[83:80] - the *maximum* read block length
sathguru 1:77e50c06ea01 414
sathguru 1:77e50c06ea01 415 int csd_structure = ext_bits(csd, 127, 126);
sathguru 1:77e50c06ea01 416 int c_size = ext_bits(csd, 73, 62);
sathguru 1:77e50c06ea01 417 int c_size_mult = ext_bits(csd, 49, 47);
sathguru 1:77e50c06ea01 418 int read_bl_len = ext_bits(csd, 83, 80);
sathguru 1:77e50c06ea01 419
sathguru 1:77e50c06ea01 420 // printf("CSD_STRUCT = %d\n", csd_structure);
sathguru 1:77e50c06ea01 421
sathguru 1:77e50c06ea01 422 if(csd_structure != 0) {
sathguru 1:77e50c06ea01 423 fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n");
sathguru 1:77e50c06ea01 424 return 0;
sathguru 1:77e50c06ea01 425 }
sathguru 1:77e50c06ea01 426
sathguru 1:77e50c06ea01 427 // memory capacity = BLOCKNR * BLOCK_LEN
sathguru 1:77e50c06ea01 428 // where
sathguru 1:77e50c06ea01 429 // BLOCKNR = (C_SIZE+1) * MULT
sathguru 1:77e50c06ea01 430 // MULT = 2^(C_SIZE_MULT+2) (C_SIZE_MULT < 8)
sathguru 1:77e50c06ea01 431 // BLOCK_LEN = 2^READ_BL_LEN, (READ_BL_LEN < 12)
sathguru 1:77e50c06ea01 432
sathguru 1:77e50c06ea01 433 int block_len = 1 << read_bl_len;
sathguru 1:77e50c06ea01 434 int mult = 1 << (c_size_mult + 2);
sathguru 1:77e50c06ea01 435 int blocknr = (c_size + 1) * mult;
sathguru 1:77e50c06ea01 436 int capacity = blocknr * block_len;
sathguru 1:77e50c06ea01 437
sathguru 1:77e50c06ea01 438 int blocks = capacity / 512;
sathguru 1:77e50c06ea01 439
sathguru 1:77e50c06ea01 440 return blocks;
sathguru 1:77e50c06ea01 441 }