Library for SD card
Dependents: SDFileSystem_HelloWorld Sharp_ce140f_emul
SDFileSystem.cpp
- Committer:
- ffxx68
- Date:
- 20 months ago
- Revision:
- 2:02f003d025a7
- Parent:
- 1:3488faedd0d1
File content as of revision 2:02f003d025a7:
/* mbed Microcontroller Library * Copyright (c) 2006-2012 ARM Limited * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ /* Introduction * ------------ * SD and MMC cards support a number of interfaces, but common to them all * is one based on SPI. This is the one I'm implmenting because it means * it is much more portable even though not so performant, and we already * have the mbed SPI Interface! * * The main reference I'm using is Chapter 7, "SPI Mode" of: * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf * * SPI Startup * ----------- * The SD card powers up in SD mode. The start-up procedure is complicated * by the requirement to support older SDCards in a backwards compatible * way with the new higher capacity variants SDHC and SDHC. * * The following figures from the specification with associated text describe * the SPI mode initialisation process: * - Figure 7-1: SD Memory Card State Diagram (SPI mode) * - Figure 7-2: SPI Mode Initialization Flow * * Firstly, a low initial clock should be selected (in the range of 100- * 400kHZ). After initialisation has been completed, the switch to a * higher clock speed can be made (e.g. 1MHz). Newer cards will support * higher speeds than the default _transfer_sck defined here. * * After power up, we need to provide at least 1 msec delay and 74 clock cycles * before sending any command to an SD Card. Since we get 8 clock cycles with each byte, * we can send 10 bytes for a total of 80 clock cycles. * The SDCard spec also specifies that CS must be held high during this period. * * Next, note the following from the SDCard specification (note to * Figure 7-1): * * In any of the cases CMD1 is not recommended because it may be difficult for the host * to distinguish between MultiMediaCard and SD Memory Card * * Hence CMD1 is not used for the initialisation sequence. * * The SPI interface mode is selected by asserting CS low and sending the * reset command (CMD0). The card will respond with a (R1) response. * In practice many cards initially respond with 0xff or invalid data * which is ignored. Data is read until a valid response is received * or the number of re-reads has exceeded a maximim count. If a valid * response is not received then the CMD0 can be retried. This * has been found to successfully initialise cards where the SPI master * (on MCU) has been reset but the SDCard has not, so the first * CMD0 may be lost. * * CMD8 is optionally sent to determine the voltage range supported, and * indirectly determine whether it is a version 1.x SD/non-SD card or * version 2.x. I'll just ignore this for now. * * ACMD41 is repeatedly issued to initialise the card, until "in idle" * (bit 0) of the R1 response goes to '0', indicating it is initialised. * * You should also indicate whether the host supports High Capicity cards, * and check whether the card is high capacity - i'll also ignore this * * SPI Protocol * ------------ * The SD SPI protocol is based on transactions made up of 8-bit words, with * the host starting every bus transaction by asserting the CS signal low. The * card always responds to commands, data blocks and errors. * * The protocol supports a CRC, but by default it is off (except for the * first reset CMD0, where the CRC can just be pre-calculated, and CMD8) * I'll leave the CRC off I think! * * Standard capacity cards have variable data block sizes, whereas High * Capacity cards fix the size of data block to 512 bytes. I'll therefore * just always use the Standard Capacity cards with a block size of 512 bytes. * This is set with CMD16. * * You can read and write single blocks (CMD17, CMD25) or multiple blocks * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When * the card gets a read command, it responds with a response token, and then * a data token or an error. * * SPI Command Format * ------------------ * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC. * * +---------------+------------+------------+-----------+----------+--------------+ * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 | * +---------------+------------+------------+-----------+----------+--------------+ * * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95) * * All Application Specific commands shall be preceded with APP_CMD (CMD55). * * SPI Response Format * ------------------- * The main response format (R1) is a status byte (normally zero). Key flags: * idle - 1 if the card is in an idle state/initialising * cmd - 1 if an illegal command code was detected * * +-------------------------------------------------+ * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle | * +-------------------------------------------------+ * * R1b is the same, except it is followed by a busy signal (zeros) until * the first non-zero byte when it is ready again. * * Data Response Token * ------------------- * Every data block written to the card is acknowledged by a byte * response token * * +----------------------+ * | xxx | 0 | status | 1 | * +----------------------+ * 010 - OK! * 101 - CRC Error * 110 - Write Error * * Single Block Read and Write * --------------------------- * * Block transfers have a byte header, followed by the data, followed * by a 16-bit CRC. In our case, the data will always be 512 bytes. * * +------+---------+---------+- - - -+---------+-----------+----------+ * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] | * +------+---------+---------+- - - -+---------+-----------+----------+ * * * */ #include "SDFileSystem.h" #include "mbed_debug.h" #define SD_COMMAND_TIMEOUT 15/*5000*/ #define SD_CMD0_GO_IDLE_STATE_RETRIES 3 #define SD_CMD0_GO_IDLE_STATE 0x00 #define SD_DBG 0 SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) : FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs), _is_initialized(0) { _cs = 1; // Set default frquency, for initialisation and data transfer _init_sck = 400000; _transfer_sck = 1000000; } // R1 bits #define R1_IDLE_STATE (1 << 0) #define R1_ERASE_RESET (1 << 1) #define R1_ILLEGAL_COMMAND (1 << 2) #define R1_COM_CRC_ERROR (1 << 3) #define R1_ERASE_SEQUENCE_ERROR (1 << 4) #define R1_ADDRESS_ERROR (1 << 5) #define R1_PARAMETER_ERROR (1 << 6) // Types // - v1.x Standard Capacity // - v2.x Standard Capacity // - v2.x High Capacity // - Not recognised as an SD Card #define SDCARD_FAIL 0 #define SDCARD_V1 1 #define SDCARD_V2 2 #define SDCARD_V2HC 3 /* SDFileSystem::_go_idle_state() * * ARGUMENTS * None * DETAILS: * Put the SDCard into the SPI Mode idle state by sending the CMD0 * (GO_IDLE_STATE) command. See the notes in the "SPI Startup" section * of the comments at the head of this file. * * RETURN: * -1 an error occured e.g. a valid response was not received. * R1_IDLE_STATE (0x1), the successful response from CMD0. */ int SDFileSystem::_go_idle_state() { _spi.lock(); int cmd_arg = 0; /* CMD0 argument is just "stuff bits"*/ /* Resetting the MCU SPI master may not reset the on-board SDCard, in which * case when MCU power-on occurs the SDCard will resume operations as * though there was no reset. In this scenario the first CMD0 will * not be interpretted as a command and get lost. For some cards retrying * the command overcomes this situation. */ for (int num_retries = 0; num_retries < SD_CMD0_GO_IDLE_STATE_RETRIES; num_retries++) { // Set to SCK for initialisation, and clock card with CS high _cs = 1; // Initial delay wait_us (1000); // Initial 74 cycles required for few cards, before selecting SPI mode for (int i = 0; i < 16; i++) { _spi.write(0xFF); } /* send a CMD0, with /CS asserted low */ _cs = 0; wait_us (1000); _spi.write(0x40 | SD_CMD0_GO_IDLE_STATE); _spi.write(cmd_arg >> 24); _spi.write(cmd_arg >> 16); _spi.write(cmd_arg >> 8); _spi.write(cmd_arg >> 0); _spi.write(0x95); // wait for the response (response[7] == 0) for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { int response = _spi.write(0xFF); /* Explicitly check for the R1_IDLE_STATE response rather that most significant bit * being 0 because invalid data can be returned. */ if (response != R1_IDLE_STATE) debug_if(SD_DBG, "CMD0 #%d (retry #%d) response: 0x%.2X\n", i, num_retries, response); else { _cs = 1; _spi.write(0xFF); _spi.unlock(); return response; } wait_us(1000); } } _cs = 1; _spi.write(0xFF); _spi.unlock(); return -1; // timeout } int SDFileSystem::initialise_card() { _spi.lock(); _spi.format(8, 0); _spi.frequency(_init_sck); _spi.unlock(); /* moved within _go_idle_state _cs = 1; // Initial delay wait_us (1000); // Initial 74 cycles required for few cards, before selecting SPI mode for (int i = 0; i < 16; i++) { _spi.write(0xFF); } */ /* Transition from SD Card mode to SPI mode by sending CMD0 GO_IDLE_STATE command */ if (_go_idle_state() != R1_IDLE_STATE) { debug_if(SD_DBG, "No disk, or could not put SD card in to SPI idle state\n"); return SDCARD_FAIL; } /* send CMD0, should return with all zeros except IDLE STATE set (bit 0) if (_cmd(0, 0) != R1_IDLE_STATE) { debug("No disk, or could not put SD card in to SPI idle state\n"); return SDCARD_FAIL; } */ // send CMD8 to determine whther it is ver 2.x int r = _cmd8(); if (r == R1_IDLE_STATE) { return initialise_card_v2(); } else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) { return initialise_card_v1(); } else { debug("Not in idle state after sending CMD8 (not an SD card?)\n"); return SDCARD_FAIL; } } int SDFileSystem::initialise_card_v1() { for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { _cmd(55, 0); if (_cmd(41, 0) == 0) { cdv = 512; debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r"); return SDCARD_V1; } } debug("Timeout waiting for v1.x card\n"); return SDCARD_FAIL; } int SDFileSystem::initialise_card_v2() { for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { wait_ms(50); _cmd58(); _cmd(55, 0); if (_cmd(41, 0x40000000) == 0) { _cmd58(); debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r"); cdv = 1; return SDCARD_V2; } } debug("Timeout waiting for v2.x card\n"); return SDCARD_FAIL; } int SDFileSystem::disk_initialize() { _is_initialized = initialise_card(); if (_is_initialized == 0) { debug("Fail to initialize card\n"); return 1; } debug_if(SD_DBG, "init card = %d\n", _is_initialized); _sectors = _sd_sectors(); // Set block length to 512 (CMD16) if (_cmd(16, 512) != 0) { debug("Set 512-byte block timed out\n"); return 1; } // Set SCK for data transfer _spi.frequency(_transfer_sck); return 0; } int SDFileSystem::disk_write(const uint8_t* buffer, uint32_t block_number, uint32_t count) { if (!_is_initialized) { return -1; } for (uint32_t b = block_number; b < block_number + count; b++) { // set write address for single block (CMD24) if (_cmd(24, b * cdv) != 0) { return 1; } // send the data block _write(buffer, 512); buffer += 512; } return 0; } int SDFileSystem::disk_read(uint8_t* buffer, uint32_t block_number, uint32_t count) { if (!_is_initialized) { return -1; } for (uint32_t b = block_number; b < block_number + count; b++) { // set read address for single block (CMD17) if (_cmd(17, b * cdv) != 0) { return 1; } // receive the data _read(buffer, 512); buffer += 512; } return 0; } int SDFileSystem::disk_status() { // FATFileSystem::disk_status() returns 0 when initialized if (_is_initialized) { return 0; } else { return 1; } } int SDFileSystem::disk_sync() { return 0; } uint32_t SDFileSystem::disk_sectors() { return _sectors; } // PRIVATE FUNCTIONS int SDFileSystem::_cmd(int cmd, int arg) { _cs = 0; // send a command _spi.write(0x40 | cmd); _spi.write(arg >> 24); _spi.write(arg >> 16); _spi.write(arg >> 8); _spi.write(arg >> 0); _spi.write(0x95); // wait for the repsonse (response[7] == 0) for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { int response = _spi.write(0xFF); if (!(response & 0x80)) { _cs = 1; _spi.write(0xFF); return response; } } _cs = 1; _spi.write(0xFF); return -1; // timeout } int SDFileSystem::_cmdx(int cmd, int arg) { _cs = 0; // send a command _spi.write(0x40 | cmd); _spi.write(arg >> 24); _spi.write(arg >> 16); _spi.write(arg >> 8); _spi.write(arg >> 0); _spi.write(0x95); // wait for the repsonse (response[7] == 0) for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { int response = _spi.write(0xFF); if (!(response & 0x80)) { return response; } } _cs = 1; _spi.write(0xFF); return -1; // timeout } int SDFileSystem::_cmd58() { _cs = 0; int arg = 0; // send a command _spi.write(0x40 | 58); _spi.write(arg >> 24); _spi.write(arg >> 16); _spi.write(arg >> 8); _spi.write(arg >> 0); _spi.write(0x95); // wait for the repsonse (response[7] == 0) for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) { int response = _spi.write(0xFF); if (!(response & 0x80)) { int ocr = _spi.write(0xFF) << 24; ocr |= _spi.write(0xFF) << 16; ocr |= _spi.write(0xFF) << 8; ocr |= _spi.write(0xFF) << 0; _cs = 1; _spi.write(0xFF); return response; } } _cs = 1; _spi.write(0xFF); return -1; // timeout } int SDFileSystem::_cmd8() { _cs = 0; // send a command _spi.write(0x40 | 8); // CMD8 _spi.write(0x00); // reserved _spi.write(0x00); // reserved _spi.write(0x01); // 3.3v _spi.write(0xAA); // check pattern _spi.write(0x87); // crc // wait for the repsonse (response[7] == 0) for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) { char response[5]; response[0] = _spi.write(0xFF); if (!(response[0] & 0x80)) { for (int j = 1; j < 5; j++) { response[i] = _spi.write(0xFF); } _cs = 1; _spi.write(0xFF); return response[0]; } } _cs = 1; _spi.write(0xFF); return -1; // timeout } int SDFileSystem::_read(uint8_t *buffer, uint32_t length) { _cs = 0; // read until start byte (0xFF) while (_spi.write(0xFF) != 0xFE); // read data for (uint32_t i = 0; i < length; i++) { buffer[i] = _spi.write(0xFF); } _spi.write(0xFF); // checksum _spi.write(0xFF); _cs = 1; _spi.write(0xFF); return 0; } int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) { _cs = 0; // indicate start of block _spi.write(0xFE); // write the data for (uint32_t i = 0; i < length; i++) { _spi.write(buffer[i]); } // write the checksum _spi.write(0xFF); _spi.write(0xFF); // check the response token if ((_spi.write(0xFF) & 0x1F) != 0x05) { _cs = 1; _spi.write(0xFF); return 1; } // wait for write to finish while (_spi.write(0xFF) == 0); _cs = 1; _spi.write(0xFF); return 0; } static uint32_t ext_bits(unsigned char *data, int msb, int lsb) { uint32_t bits = 0; uint32_t size = 1 + msb - lsb; for (uint32_t i = 0; i < size; i++) { uint32_t position = lsb + i; uint32_t byte = 15 - (position >> 3); uint32_t bit = position & 0x7; uint32_t value = (data[byte] >> bit) & 1; bits |= value << i; } return bits; } uint32_t SDFileSystem::_sd_sectors() { uint32_t c_size, c_size_mult, read_bl_len; uint32_t block_len, mult, blocknr, capacity; uint32_t hc_c_size; uint32_t blocks; // CMD9, Response R2 (R1 byte + 16-byte block read) if (_cmdx(9, 0) != 0) { debug("Didn't get a response from the disk\n"); return 0; } uint8_t csd[16]; if (_read(csd, 16) != 0) { debug("Couldn't read csd response from disk\n"); return 0; } // csd_structure : csd[127:126] // c_size : csd[73:62] // c_size_mult : csd[49:47] // read_bl_len : csd[83:80] - the *maximum* read block length int csd_structure = ext_bits(csd, 127, 126); switch (csd_structure) { case 0: cdv = 512; c_size = ext_bits(csd, 73, 62); c_size_mult = ext_bits(csd, 49, 47); read_bl_len = ext_bits(csd, 83, 80); block_len = 1 << read_bl_len; mult = 1 << (c_size_mult + 2); blocknr = (c_size + 1) * mult; capacity = blocknr * block_len; blocks = capacity / 512; debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks); break; case 1: cdv = 1; hc_c_size = ext_bits(csd, 63, 48); blocks = (hc_c_size+1)*1024; 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); break; default: debug("CSD struct unsupported\r\n"); return 0; }; return blocks; }