micro SD Card module, Normal SPI CS mode. detail : http://wizard.nestegg.jp/sd.html http://wizard.nestegg.jp/spisetting.html
Diff: SDFileSystem.cpp
- Revision:
- 0:e7f811d99fdb
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SDFileSystem.cpp Mon Jul 25 08:06:37 2011 +0000 @@ -0,0 +1,441 @@ +/* mbed Microcontroller Library - SDFileSystem + * Copyright (c) 2008-2009, sford + */ + +// VERY DRAFT CODE! Needs serious rework/refactoring + +/* 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 SPI interface mode is selected by + * asserting CS low and sending the reset command (CMD0). The card will + * respond with a (R1) response. + * + * 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" + +#define SD_COMMAND_TIMEOUT 5000 + +SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) : + FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) { + _cs = 1; +} + +#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 + +int SDFileSystem::initialise_card() { + // Set to 100kHz for initialisation, and clock card with cs = 1 + _spi.frequency(100000); + _cs = 1; + for(int i=0; i<16; i++) { + _spi.write(0xFF); + } + + // send CMD0, should return with all zeros except IDLE STATE set (bit 0) + if(_cmd(0, 0) != R1_IDLE_STATE) { + fprintf(stderr, "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 { + fprintf(stderr, "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) { + return SDCARD_V1; + } + } + + fprintf(stderr, "Timeout waiting for v1.x card\n"); + return SDCARD_FAIL; +} + +int SDFileSystem::initialise_card_v2() { + + for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { + _cmd(55, 0); + if(_cmd(41, 0) == 0) { + _cmd58(); + return SDCARD_V2; + } + } + + fprintf(stderr, "Timeout waiting for v2.x card\n"); + return SDCARD_FAIL; +} + +int SDFileSystem::disk_initialize() { + + int i = initialise_card(); +// printf("init card = %d\n", i); +// printf("OK\n"); + + _sectors = _sd_sectors(); + + // Set block length to 512 (CMD16) + if(_cmd(16, 512) != 0) { + fprintf(stderr, "Set 512-byte block timed out\n"); + return 1; + } + + _spi.frequency(1000000); // Set to 1MHz for data transfer + return 0; +} + +int SDFileSystem::disk_write(const char *buffer, int block_number) { + // set write address for single block (CMD24) + if(_cmd(24, block_number * 512) != 0) { + return 1; + } + + // send the data block + _write(buffer, 512); + return 0; +} + +int SDFileSystem::disk_read(char *buffer, int block_number) { + // set read address for single block (CMD17) + if(_cmd(17, block_number * 512) != 0) { + return 1; + } + + // receive the data + _read(buffer, 512); + return 0; +} + +int SDFileSystem::disk_status() { return 0; } +int SDFileSystem::disk_sync() { return 0; } +int 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; +// printf("OCR = 0x%08X\n", ocr); + _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(char *buffer, int length) { + _cs = 0; + + // read until start byte (0xFF) + while(_spi.write(0xFF) != 0xFE); + + // read data + for(int 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 char *buffer, int length) { + _cs = 0; + + // indicate start of block + _spi.write(0xFE); + + // write the data + for(int i=0; i<length; i++) { + _spi.write(buffer[i]); + } + + // write the checksum + _spi.write(0xFF); + _spi.write(0xFF); + + // check the repsonse 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 int ext_bits(char *data, int msb, int lsb) { + int bits = 0; + int size = 1 + msb - lsb; + for(int i=0; i<size; i++) { + int position = lsb + i; + int byte = 15 - (position >> 3); + int bit = position & 0x7; + int value = (data[byte] >> bit) & 1; + bits |= value << i; + } + return bits; +} + +int SDFileSystem::_sd_sectors() { + + // CMD9, Response R2 (R1 byte + 16-byte block read) + if(_cmdx(9, 0) != 0) { + fprintf(stderr, "Didn't get a response from the disk\n"); + return 0; + } + + char csd[16]; + if(_read(csd, 16) != 0) { + fprintf(stderr, "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); + int c_size = ext_bits(csd, 73, 62); + int c_size_mult = ext_bits(csd, 49, 47); + int read_bl_len = ext_bits(csd, 83, 80); + +// printf("CSD_STRUCT = %d\n", csd_structure); + + if(csd_structure != 0) { + fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n"); + return 0; + } + + // memory capacity = BLOCKNR * BLOCK_LEN + // where + // BLOCKNR = (C_SIZE+1) * MULT + // MULT = 2^(C_SIZE_MULT+2) (C_SIZE_MULT < 8) + // BLOCK_LEN = 2^READ_BL_LEN, (READ_BL_LEN < 12) + + int block_len = 1 << read_bl_len; + int mult = 1 << (c_size_mult + 2); + int blocknr = (c_size + 1) * mult; + int capacity = blocknr * block_len; + + int blocks = capacity / 512; + + return blocks; +}