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- /* 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 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"
- #include "mbed_debug.h"
-
- #define SD_COMMAND_TIMEOUT 5000
-
- #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 to 100kHz for initialisation and 1MHz for data transfer
- _init_sck = 100000;
- _transfer_sck = 1000000;
- }
-
- #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 SCK for initialisation, and clock card with cs = 1
- _spi.frequency(_init_sck);
- _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) {
- 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, uint64_t block_number, uint8_t count) {
- if (!_is_initialized) {
- return -1;
- }
-
- for (uint64_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, uint64_t block_number, uint8_t count) {
- if (!_is_initialized) {
- return -1;
- }
-
- for (uint64_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; }
- uint64_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;
- }
-
- uint64_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;
- uint64_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;
- }
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