A simple digital lock with attempted audio guidance
Dependencies: FATFileSystem TextLCD mbed
Fork of Digital_Lock_with_audio by
SDFileSystem.cpp
00001 /* mbed Microcontroller Library - SDFileSystem 00002 * Copyright (c) 2008-2009, sford 00003 * 00004 * Introduction 00005 * ------------ 00006 * SD and MMC cards support a number of interfaces, but common to them all 00007 * is one based on SPI. This is the one I'm implmenting because it means 00008 * it is much more portable even though not so performant, and we already 00009 * have the mbed SPI Interface! 00010 * 00011 * The main reference I'm using is Chapter 7, "SPI Mode" of: 00012 * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf 00013 * 00014 * SPI Startup 00015 * ----------- 00016 * The SD card powers up in SD mode. The SPI interface mode is selected by 00017 * asserting CS low and sending the reset command (CMD0). The card will 00018 * respond with a (R1) response. 00019 * 00020 * CMD8 is optionally sent to determine the voltage range supported, and 00021 * indirectly determine whether it is a version 1.x SD/non-SD card or 00022 * version 2.x. I'll just ignore this for now. 00023 * 00024 * ACMD41 is repeatedly issued to initialise the card, until "in idle" 00025 * (bit 0) of the R1 response goes to '0', indicating it is initialised. 00026 * 00027 * You should also indicate whether the host supports High Capicity cards, 00028 * and check whether the card is high capacity - i'll also ignore this 00029 * 00030 * SPI Protocol 00031 * ------------ 00032 * The SD SPI protocol is based on transactions made up of 8-bit words, with 00033 * the host starting every bus transaction by asserting the CS signal low. The 00034 * card always responds to commands, data blocks and errors. 00035 * 00036 * The protocol supports a CRC, but by default it is off (except for the 00037 * first reset CMD0, where the CRC can just be pre-calculated, and CMD8) 00038 * I'll leave the CRC off I think! 00039 * 00040 * Standard capacity cards have variable data block sizes, whereas High 00041 * Capacity cards fix the size of data block to 512 bytes. I'll therefore 00042 * just always use the Standard Capacity cards with a block size of 512 bytes. 00043 * This is set with CMD16. 00044 * 00045 * You can read and write single blocks (CMD17, CMD25) or multiple blocks 00046 * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When 00047 * the card gets a read command, it responds with a response token, and then 00048 * a data token or an error. 00049 * 00050 * SPI Command Format 00051 * ------------------ 00052 * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC. 00053 * 00054 * +---------------+------------+------------+-----------+----------+--------------+ 00055 * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 | 00056 * +---------------+------------+------------+-----------+----------+--------------+ 00057 * 00058 * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95) 00059 * 00060 * All Application Specific commands shall be preceded with APP_CMD (CMD55). 00061 * 00062 * SPI Response Format 00063 * ------------------- 00064 * The main response format (R1) is a status byte (normally zero). Key flags: 00065 * idle - 1 if the card is in an idle state/initialising 00066 * cmd - 1 if an illegal command code was detected 00067 * 00068 * +-------------------------------------------------+ 00069 * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle | 00070 * +-------------------------------------------------+ 00071 * 00072 * R1b is the same, except it is followed by a busy signal (zeros) until 00073 * the first non-zero byte when it is ready again. 00074 * 00075 * Data Response Token 00076 * ------------------- 00077 * Every data block written to the card is acknowledged by a byte 00078 * response token 00079 * 00080 * +----------------------+ 00081 * | xxx | 0 | status | 1 | 00082 * +----------------------+ 00083 * 010 - OK! 00084 * 101 - CRC Error 00085 * 110 - Write Error 00086 * 00087 * Single Block Read and Write 00088 * --------------------------- 00089 * 00090 * Block transfers have a byte header, followed by the data, followed 00091 * by a 16-bit CRC. In our case, the data will always be 512 bytes. 00092 * 00093 * +------+---------+---------+- - - -+---------+-----------+----------+ 00094 * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] | 00095 * +------+---------+---------+- - - -+---------+-----------+----------+ 00096 */ 00097 00098 #include "SDFileSystem.h" 00099 00100 #define SD_COMMAND_TIMEOUT 5000 00101 00102 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) : 00103 FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) { 00104 _cs = 1; 00105 } 00106 00107 int SDFileSystem::disk_initialize() { 00108 00109 _spi.frequency(100000); // Set to 100kHz for initialisation 00110 00111 // Initialise the card by clocking it with cs = 1 00112 _cs = 1; 00113 for(int i=0; i<16; i++) { 00114 _spi.write(0xFF); 00115 } 00116 00117 // send CMD0, should return with all zeros except IDLE STATE set (bit 0) 00118 if(_cmd(0, 0) != 0x01) { 00119 fprintf(stderr, "Not in idle state\n"); 00120 return 1; 00121 } 00122 00123 // ACMD41 to give host capacity support (repeat until not busy) 00124 // ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand 00125 for(int i=0;; i++) { 00126 _cmd(55, 0); 00127 int response = _cmd(41, 0); 00128 if(response == 0) { 00129 break; 00130 } else if(i > SD_COMMAND_TIMEOUT) { 00131 fprintf(stderr, "Timeout waiting for card\n"); 00132 return 1; 00133 } 00134 } 00135 00136 _sectors = _sd_sectors(); 00137 00138 // Set block length to 512 (CMD16) 00139 if(_cmd(16, 512) != 0) { 00140 fprintf(stderr, "Set block timeout\n"); 00141 return 1; 00142 } 00143 00144 _spi.frequency(1000000); // Set to 1MHz for data transfer 00145 return 0; 00146 } 00147 00148 int SDFileSystem::disk_write(const char *buffer, int block_number) { 00149 // set write address for single block (CMD24) 00150 if(_cmd(24, block_number * 512) != 0) { 00151 return 1; 00152 } 00153 00154 // send the data block 00155 _write(buffer, 512); 00156 return 0; 00157 } 00158 00159 int SDFileSystem::disk_read(char *buffer, int block_number) { 00160 // set read address for single block (CMD17) 00161 if(_cmd(17, block_number * 512) != 0) { 00162 return 1; 00163 } 00164 00165 // receive the data 00166 _read(buffer, 512); 00167 return 0; 00168 } 00169 00170 int SDFileSystem::disk_status() { return 0; } 00171 int SDFileSystem::disk_sync() { return 0; } 00172 int SDFileSystem::disk_sectors() { return _sectors; } 00173 00174 // PRIVATE FUNCTIONS 00175 00176 int SDFileSystem::_cmd(int cmd, int arg) { 00177 _cs = 0; 00178 00179 // send a command 00180 _spi.write(0x40 | cmd); 00181 _spi.write(arg >> 24); 00182 _spi.write(arg >> 16); 00183 _spi.write(arg >> 8); 00184 _spi.write(arg >> 0); 00185 _spi.write(0x95); 00186 00187 // wait for the repsonse (response[7] == 0) 00188 for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { 00189 int response = _spi.write(0xFF); 00190 if(!(response & 0x80)) { 00191 _cs = 1; 00192 _spi.write(0xFF); 00193 return response; 00194 } 00195 } 00196 _cs = 1; 00197 _spi.write(0xFF); 00198 return -1; // timeout 00199 } 00200 00201 int SDFileSystem::_read(char *buffer, int length) { 00202 _cs = 0; 00203 00204 // read until start byte (0xFF) 00205 while(_spi.write(0xFF) != 0xFE); 00206 00207 // read data 00208 for(int i=0; i<length; i++) { 00209 buffer[i] = _spi.write(0xFF); 00210 } 00211 _spi.write(0xFF); // checksum 00212 _spi.write(0xFF); 00213 00214 _cs = 1; 00215 _spi.write(0xFF); 00216 return 0; 00217 } 00218 00219 int SDFileSystem::_write(const char *buffer, int length) { 00220 _cs = 0; 00221 00222 // indicate start of block 00223 _spi.write(0xFE); 00224 00225 // write the data 00226 for(int i=0; i<length; i++) { 00227 _spi.write(buffer[i]); 00228 } 00229 00230 // write the checksum 00231 _spi.write(0xFF); 00232 _spi.write(0xFF); 00233 00234 // check the repsonse token 00235 if((_spi.write(0xFF) & 0x1F) != 0x05) { 00236 _cs = 1; 00237 _spi.write(0xFF); 00238 return 1; 00239 } 00240 00241 // wait for write to finish 00242 while(_spi.write(0xFF) == 0); 00243 00244 _cs = 1; 00245 _spi.write(0xFF); 00246 return 0; 00247 } 00248 00249 static int ext_bits(char *data, int msb, int lsb) { 00250 int bits = 0; 00251 int size = 1 + msb - lsb; 00252 for(int i=0; i<size; i++) { 00253 int position = lsb + i; 00254 int byte = 15 - (position >> 3); 00255 int bit = position & 0x7; 00256 int value = (data[byte] >> bit) & 1; 00257 bits |= value << i; 00258 } 00259 return bits; 00260 } 00261 00262 int SDFileSystem::_sd_sectors() { 00263 00264 // CMD9, Response R2 (R1 byte + 16-byte block read) 00265 if(_cmd(9, 0) != 0) { 00266 fprintf(stderr, "Didn't get a response from the disk\n"); 00267 return 0; 00268 } 00269 00270 char csd[16]; 00271 if(_read(csd, 16) != 0) { 00272 fprintf(stderr, "Couldn't read csd response from disk\n"); 00273 return 0; 00274 } 00275 00276 // csd_structure : csd[127:126] 00277 // c_size : csd[73:62] 00278 // c_size_mult : csd[49:47] 00279 // read_bl_len : csd[83:80] 00280 00281 int csd_structure = ext_bits(csd, 127, 126); 00282 int c_size = ext_bits(csd, 73, 62); 00283 int c_size_mult = ext_bits(csd, 49, 47); 00284 int read_bl_len = ext_bits(csd, 83, 80); 00285 00286 if(csd_structure != 0) { 00287 fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures"); 00288 return 0; 00289 } 00290 00291 int blocks = (c_size + 1) * (1 << (c_size_mult + 2)); 00292 int block_size = 1 << read_bl_len; 00293 00294 if(block_size != 512) { 00295 fprintf(stderr, "This disk tastes funny! I only like 512-byte blocks"); 00296 return 0; 00297 } 00298 00299 return blocks; 00300 }
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