SDHCFileSystem in a library. Requires FatFileSystem

Dependents:   sdhc_speed_test ZY_FGD1442701V1_BusOut_SDHC frdm_gpio SDcard

Files at this revision

API Documentation at this revision

Comitter:
tylerjw
Date:
Mon Oct 15 18:35:58 2012 +0000
Commit message:
SDHC FileSystem placed in a library.; ; Requires FatFileSystem

Changed in this revision

SDHCFileSystem.cpp Show annotated file Show diff for this revision Revisions of this file
SDHCFileSystem.h Show annotated file Show diff for this revision Revisions of this file
diff -r 000000000000 -r b553aa902f90 SDHCFileSystem.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDHCFileSystem.cpp	Mon Oct 15 18:35:58 2012 +0000
@@ -0,0 +1,495 @@
+/* mbed SDFileSystem Library, for providing file access to SD cards
+ * Copyright (c) 2008-2010, sford
+ *
+ * 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] | 
+ * +------+---------+---------+- -  - -+---------+-----------+----------+
+ */
+ 
+ /*
+ * Comment: Changes for SDHC support till 32GB 
+ * Name:    KB
+ * Date:    07/24/2010
+ * Release: 0.1
+ */
+ 
+#include "SDHCFileSystem.h"
+
+#define DEBUG
+#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) { 
+            cdv = 512;
+            #ifdef DEBUG 
+            printf("\n\rInit: SEDCARD_V1\n\r");
+            #endif
+            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++) {
+        wait_ms(50);
+        _cmd58();
+        _cmd(55, 0); 
+        if(_cmd(41, 0x40000000) == 0) { 
+            _cmd58();
+            #ifdef DEBUG
+            printf("\n\rInit: SDCARD_V2\n\r");
+            #endif
+            cdv = 1;
+            return SDCARD_V2;
+        }
+    }
+
+    fprintf(stderr, "Timeout waiting for v2.x card\n");
+    return SDCARD_FAIL;
+}
+
+int SDFileSystem::disk_initialize() {
+
+    int i = initialise_card();
+    #ifdef DEBUG 
+    printf("init card = %d\n", i);
+    #endif
+    _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 * cdv) != 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 * cdv) != 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() {
+
+    int c_size, c_size_mult, read_bl_len;
+    int block_len, mult, blocknr, capacity;       
+    int blocks, hc_c_size;
+    uint64_t hc_capacity;
+     
+    // 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);
+    
+    #ifdef DEBUG 
+    printf("\n\rCSD_STRUCT = %d\n", csd_structure);
+    #endif
+     
+    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;
+      #ifdef DEBUG 
+      printf("\n\rSDCard\n\rc_size: %.4X \n\rcapacity: %.ld \n\rsectors: %d\n\r", c_size, capacity, blocks);
+      #endif
+      break;
+    
+     case 1:
+      cdv = 1;
+      hc_c_size = ext_bits(csd, 63, 48);
+      int hc_read_bl_len = ext_bits(csd, 83, 80);
+      hc_capacity = hc_c_size+1;   
+      blocks = (hc_c_size+1)*1024;
+      #ifdef DEBUG 
+      printf("\n\rSDHC Card \n\rhc_c_size: %.4X \n\rcapacity: %.lld \n\rsectors: %d\n\r", hc_c_size, hc_capacity*512*1024, blocks);
+      #endif
+      break;
+   
+    default:    
+       fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures\n");
+     return 0;
+     break;
+    };
+ return blocks;
+}
diff -r 000000000000 -r b553aa902f90 SDHCFileSystem.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDHCFileSystem.h	Mon Oct 15 18:35:58 2012 +0000
@@ -0,0 +1,86 @@
+/* mbed SDFileSystem Library, for providing file access to SD cards
+ * Copyright (c) 2008-2010, sford
+ *
+ * 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.
+ */
+
+#ifndef MBED_SDHCFILESYSTEM_H
+#define MBED_SDHCFILESYSTEM_H
+
+#include "mbed.h"
+#include "FATFileSystem.h"
+
+/* Double Words */
+typedef unsigned long long uint64_t;
+typedef long long sint64_t;
+
+/** Access the filesystem on an SD Card using SPI
+ *
+ * @code
+ * #include "mbed.h"
+ * #include "SDFileSystem.h"
+ *
+ * SDFileSystem sd(p5, p6, p7, p12, "sd"); // mosi, miso, sclk, cs
+ *  
+ * int main() {
+ *     FILE *fp = fopen("/sd/myfile.txt", "w");
+ *     fprintf(fp, "Hello World!\n");
+ *     fclose(fp);
+ * }
+ */
+class SDFileSystem : public FATFileSystem {
+public:
+
+    /** Create the File System for accessing an SD Card using SPI
+     *
+     * @param mosi SPI mosi pin connected to SD Card
+     * @param miso SPI miso pin conencted to SD Card
+     * @param sclk SPI sclk pin connected to SD Card
+     * @param cs   DigitalOut pin used as SD Card chip select
+     * @param name The name used to access the virtual filesystem
+     */
+    SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name);
+    virtual int disk_initialize();
+    virtual int disk_write(const char *buffer, int block_number);
+    virtual int disk_read(char *buffer, int block_number);    
+    virtual int disk_status();
+    virtual int disk_sync();
+    virtual int disk_sectors();
+
+protected:
+
+    int _cmd(int cmd, int arg);
+    int _cmdx(int cmd, int arg);
+    int _cmd8();
+    int _cmd58();
+    int initialise_card();
+    int initialise_card_v1();
+    int initialise_card_v2();
+    
+    int _read(char *buffer, int length);
+    int _write(const char *buffer, int length);
+    int _sd_sectors();
+    int _sectors;
+    
+    SPI _spi;
+    DigitalOut _cs; 
+    int cdv;    
+};
+
+#endif