Revision 0:583b9f0b91e7, committed 2016-10-13

Comitter:

sameera0824

Date:

Thu Oct 13 10:51:33 2016 +0000

Commit message:

adding SD

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FATFileSystem.lib	Thu Oct 13 10:51:33 2016 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/teams/mbed-official/code/FATFileSystem/#c4baca9a2c3d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDCRC.cpp	Thu Oct 13 10:51:33 2016 +0000
@@ -0,0 +1,119 @@
+/* SD/MMC File System Library
+ * Copyright (c) 2016 Neil Thiessen
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "SDCRC.h"
+
+namespace SDCRC
+{
+
+namespace
+{
+const char m_Crc7Table[] = {
+    0x00, 0x09, 0x12, 0x1B, 0x24, 0x2D, 0x36, 0x3F,
+    0x48, 0x41, 0x5A, 0x53, 0x6C, 0x65, 0x7E, 0x77,
+    0x19, 0x10, 0x0B, 0x02, 0x3D, 0x34, 0x2F, 0x26,
+    0x51, 0x58, 0x43, 0x4A, 0x75, 0x7C, 0x67, 0x6E,
+    0x32, 0x3B, 0x20, 0x29, 0x16, 0x1F, 0x04, 0x0D,
+    0x7A, 0x73, 0x68, 0x61, 0x5E, 0x57, 0x4C, 0x45,
+    0x2B, 0x22, 0x39, 0x30, 0x0F, 0x06, 0x1D, 0x14,
+    0x63, 0x6A, 0x71, 0x78, 0x47, 0x4E, 0x55, 0x5C,
+    0x64, 0x6D, 0x76, 0x7F, 0x40, 0x49, 0x52, 0x5B,
+    0x2C, 0x25, 0x3E, 0x37, 0x08, 0x01, 0x1A, 0x13,
+    0x7D, 0x74, 0x6F, 0x66, 0x59, 0x50, 0x4B, 0x42,
+    0x35, 0x3C, 0x27, 0x2E, 0x11, 0x18, 0x03, 0x0A,
+    0x56, 0x5F, 0x44, 0x4D, 0x72, 0x7B, 0x60, 0x69,
+    0x1E, 0x17, 0x0C, 0x05, 0x3A, 0x33, 0x28, 0x21,
+    0x4F, 0x46, 0x5D, 0x54, 0x6B, 0x62, 0x79, 0x70,
+    0x07, 0x0E, 0x15, 0x1C, 0x23, 0x2A, 0x31, 0x38,
+    0x41, 0x48, 0x53, 0x5A, 0x65, 0x6C, 0x77, 0x7E,
+    0x09, 0x00, 0x1B, 0x12, 0x2D, 0x24, 0x3F, 0x36,
+    0x58, 0x51, 0x4A, 0x43, 0x7C, 0x75, 0x6E, 0x67,
+    0x10, 0x19, 0x02, 0x0B, 0x34, 0x3D, 0x26, 0x2F,
+    0x73, 0x7A, 0x61, 0x68, 0x57, 0x5E, 0x45, 0x4C,
+    0x3B, 0x32, 0x29, 0x20, 0x1F, 0x16, 0x0D, 0x04,
+    0x6A, 0x63, 0x78, 0x71, 0x4E, 0x47, 0x5C, 0x55,
+    0x22, 0x2B, 0x30, 0x39, 0x06, 0x0F, 0x14, 0x1D,
+    0x25, 0x2C, 0x37, 0x3E, 0x01, 0x08, 0x13, 0x1A,
+    0x6D, 0x64, 0x7F, 0x76, 0x49, 0x40, 0x5B, 0x52,
+    0x3C, 0x35, 0x2E, 0x27, 0x18, 0x11, 0x0A, 0x03,
+    0x74, 0x7D, 0x66, 0x6F, 0x50, 0x59, 0x42, 0x4B,
+    0x17, 0x1E, 0x05, 0x0C, 0x33, 0x3A, 0x21, 0x28,
+    0x5F, 0x56, 0x4D, 0x44, 0x7B, 0x72, 0x69, 0x60,
+    0x0E, 0x07, 0x1C, 0x15, 0x2A, 0x23, 0x38, 0x31,
+    0x46, 0x4F, 0x54, 0x5D, 0x62, 0x6B, 0x70, 0x79
+};
+
+const unsigned short m_Crc16Table[256] = {
+    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
+    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
+    0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
+    0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
+    0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
+    0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
+    0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
+    0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
+    0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
+    0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
+    0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
+    0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
+    0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
+    0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
+    0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
+    0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
+    0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
+    0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
+    0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
+    0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
+    0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
+    0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
+    0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
+    0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
+    0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
+    0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
+    0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
+    0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
+    0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
+    0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
+    0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
+    0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
+};
+}
+
+char crc7(const char* data, int length)
+{
+    //Calculate the CRC7 checksum for the specified data block
+    char crc = 0;
+    for (int i = 0; i < length; i++) {
+        crc = m_Crc7Table[(crc << 1) ^ data[i]];
+    }
+
+    //Return the calculated checksum
+    return crc;
+}
+
+unsigned short crc16(const char* data, int length)
+{
+    //Calculate the CRC16 checksum for the specified data block
+    unsigned short crc = 0;
+    for (int i = 0; i < length; i++) {
+        crc = (crc << 8) ^ m_Crc16Table[((crc >> 8) ^ data[i]) & 0x00FF];
+    }
+
+    //Return the calculated checksum
+    return crc;
+}
+
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDCRC.h	Thu Oct 13 10:51:33 2016 +0000
@@ -0,0 +1,30 @@
+/* SD/MMC File System Library
+ * Copyright (c) 2016 Neil Thiessen
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SD_CRC_H
+#define SD_CRC_H
+
+#include "mbed.h"
+
+namespace SDCRC
+{
+
+char crc7(const char* data, int length);
+unsigned short crc16(const char* data, int length);
+
+}
+
+#endif

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.cpp	Thu Oct 13 10:51:33 2016 +0000
@@ -0,0 +1,934 @@
+/* SD/MMC File System Library
+ * Copyright (c) 2016 Neil Thiessen
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "SDFileSystem.h"
+#include "diskio.h"
+#include "pinmap.h"
+#include "SDCRC.h"
+
+SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name, PinName cd, SwitchType cdtype, int hz)
+    : FATFileSystem(name),
+      m_Spi(mosi, miso, sclk),
+      m_Cs(cs, 1),
+      m_Cd(cd),
+      m_FREQ(hz)
+{
+    //Initialize the member variables
+    m_CardType = CARD_NONE;
+    m_Crc = true;
+    m_LargeFrames = false;
+    m_WriteValidation = true;
+    m_Status = STA_NOINIT;
+
+    //Enable the internal pull-up resistor on MISO
+    pin_mode(miso, PullUp);
+
+    //Configure the SPI bus
+    m_Spi.format(8, 0);
+
+    //Configure the card detect pin
+    if (cdtype == SWITCH_POS_NO) {
+        m_Cd.mode(PullDown);
+        m_CdAssert = 1;
+        m_Cd.fall(this, &SDFileSystem::onCardRemoval);
+    } else if (cdtype == SWITCH_POS_NC) {
+        m_Cd.mode(PullDown);
+        m_CdAssert = 0;
+        m_Cd.rise(this, &SDFileSystem::onCardRemoval);
+    } else if (cdtype == SWITCH_NEG_NO) {
+        m_Cd.mode(PullUp);
+        m_CdAssert = 0;
+        m_Cd.rise(this, &SDFileSystem::onCardRemoval);
+    } else if (cdtype == SWITCH_NEG_NC) {
+        m_Cd.mode(PullUp);
+        m_CdAssert = 1;
+        m_Cd.fall(this, &SDFileSystem::onCardRemoval);
+    } else {
+        m_CdAssert = -1;
+    }
+}
+
+bool SDFileSystem::card_present()
+{
+    //Check the card socket
+    checkSocket();
+
+    //Return whether or not a card is present
+    return !(m_Status & STA_NODISK);
+}
+
+SDFileSystem::CardType SDFileSystem::card_type()
+{
+    //Check the card socket
+    checkSocket();
+
+    //Return the card type
+    return m_CardType;
+}
+
+bool SDFileSystem::crc()
+{
+    //Return whether or not CRC is enabled
+    return m_Crc;
+}
+
+void SDFileSystem::crc(bool enabled)
+{
+    //Check the card socket
+    checkSocket();
+
+    //Just update the member variable if the card isn't initialized
+    if (m_Status & STA_NOINIT) {
+        m_Crc = enabled;
+        return;
+    }
+
+    //Enable or disable CRC
+    if (enabled && !m_Crc) {
+        //Send CMD59(0x00000001) to enable CRC
+        m_Crc = true;
+        commandTransaction(CMD59, 0x00000001);
+    } else if (!enabled && m_Crc) {
+        //Send CMD59(0x00000000) to disable CRC
+        commandTransaction(CMD59, 0x00000000);
+        m_Crc = false;
+    }
+}
+
+bool SDFileSystem::large_frames()
+{
+    //Return whether or not 16-bit frames are enabled
+    return m_LargeFrames;
+}
+
+void SDFileSystem::large_frames(bool enabled)
+{
+    //Set whether or not 16-bit frames are enabled
+    m_LargeFrames = enabled;
+}
+
+bool SDFileSystem::write_validation()
+{
+    //Return whether or not write validation is enabled
+    return m_WriteValidation;
+}
+
+void SDFileSystem::write_validation(bool enabled)
+{
+    //Set whether or not write validation is enabled
+    m_WriteValidation = enabled;
+}
+
+int SDFileSystem::unmount()
+{
+    //Unmount the filesystem
+    FATFileSystem::unmount();
+
+    //Change the status to not initialized, and the card type to unknown
+    m_Status |= STA_NOINIT;
+    m_CardType = CARD_UNKNOWN;
+
+    //Always succeeds
+    return 0;
+}
+
+int SDFileSystem::disk_initialize()
+{
+    char token;
+    unsigned int resp;
+    Timer timer;
+
+    //Make sure there's a card in the socket before proceeding
+    checkSocket();
+    if (m_Status & STA_NODISK)
+        return m_Status;
+
+    //Make sure we're not already initialized before proceeding
+    if (!(m_Status & STA_NOINIT))
+        return m_Status;
+
+    //Set the SPI frequency to 400kHz for initialization
+    m_Spi.frequency(400000);
+
+    //Try to reset the card up to 3 times
+    for (int f = 0; f < 3; f++) {
+        //Send 80 dummy clocks with /CS deasserted and DI held high
+        m_Cs = 1;
+        for (int i = 0; i < 10; i++) {
+            m_Spi.write(0xFF);
+        }
+
+        //Send CMD0(0x00000000) to reset the card
+        token = commandTransaction(CMD0, 0x00000000);
+        if (token == 0x01) {
+            break;
+        }
+    }
+
+    //Check if the card reset
+    if (token != 0x01) {
+        //Initialization failed
+        m_CardType = CARD_UNKNOWN;
+        return m_Status;
+    }
+
+    //Send CMD59(0x00000001) to enable CRC if necessary
+    if (m_Crc) {
+        if (commandTransaction(CMD59, 0x00000001) != 0x01) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+    }
+
+    //Send CMD8(0x000001AA) to see if this is an SDCv2 card
+    if (commandTransaction(CMD8, 0x000001AA, &resp) == 0x01) {
+        //This is an SDCv2 card, get the 32-bit return value and verify the voltage range/check pattern
+        if ((resp & 0xFFF) != 0x1AA) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Send CMD58(0x00000000) to read the OCR, and verify that the card supports 3.2-3.3V
+        if (commandTransaction(CMD58, 0x00000000, &resp) != 0x01 || !(resp & (1 << 20))) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Try to initialize the card using ACMD41(0x40100000) for up to 2 seconds
+        timer.start();
+        do {
+            token = commandTransaction(ACMD41, 0x40100000);
+        } while (token == 0x01 && timer.read_ms() < 2000);
+        timer.stop();
+        timer.reset();
+
+        //Check if the card initialized
+        if (token != 0x00) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Send CMD58(0x00000000) to read the OCR
+        if (commandTransaction(CMD58, 0x00000000, &resp) == 0x00) {
+            //Check the CCS bit to determine if this is a high capacity card
+            if (resp & (1 << 30))
+                m_CardType = CARD_SDHC;
+            else
+                m_CardType = CARD_SD;
+
+            //Increase the SPI frequency to full speed (up to 50MHz for SDCv2)
+            if (m_FREQ > 25000000) {
+                if (enableHighSpeedMode()) {
+                    if (m_FREQ > 50000000) {
+                        m_Spi.frequency(50000000);
+                    } else {
+                        m_Spi.frequency(m_FREQ);
+                    }
+                } else {
+                    m_Spi.frequency(25000000);
+                }
+            } else {
+                m_Spi.frequency(m_FREQ);
+            }
+        } else {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+    } else {
+        //Didn't respond or illegal command, this is either an SDCv1 or MMC card
+        //Send CMD58(0x00000000) to read the OCR, and verify that the card supports 3.2-3.3V
+        if (commandTransaction(CMD58, 0x00000000, &resp) != 0x01 || !(resp & (1 << 20))) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Try to initialize the card using ACMD41(0x40100000) for up to 2 seconds
+        timer.start();
+        do {
+            token = commandTransaction(ACMD41, 0x40100000);
+        } while (token == 0x01 && timer.read_ms() < 2000);
+        timer.stop();
+        timer.reset();
+
+        //Check if the card initialized
+        if (token == 0x00) {
+            //This is an SDCv1 standard capacity card
+            m_CardType = CARD_SD;
+
+            //Increase the SPI frequency to full speed (up to 25MHz for SDCv1)
+            if (m_FREQ > 25000000)
+                m_Spi.frequency(25000000);
+            else
+                m_Spi.frequency(m_FREQ);
+        } else {
+            //Try to initialize the card using CMD1(0x00100000) for up to 2 seconds
+            timer.start();
+            do {
+                token = commandTransaction(CMD1, 0x00100000);
+            } while (token == 0x01 && timer.read_ms() < 2000);
+            timer.stop();
+            timer.reset();
+
+            //Check if the card initialized
+            if (token == 0x00) {
+                //This is an MMCv3 card
+                m_CardType = CARD_MMC;
+
+                //Increase the SPI frequency to full speed (up to 20MHz for MMCv3)
+                if (m_FREQ > 20000000)
+                    m_Spi.frequency(20000000);
+                else
+                    m_Spi.frequency(m_FREQ);
+            } else {
+                //Initialization failed
+                m_CardType = CARD_UNKNOWN;
+                return m_Status;
+            }
+        }
+    }
+
+    //Send ACMD42(0x00000000) to disconnect the internal pull-up resistor on pin 1 if necessary
+    if (m_CardType != CARD_MMC) {
+        if (commandTransaction(ACMD42, 0x00000000) != 0x00) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+    }
+
+    //Send CMD16(0x00000200) to force the block size to 512B if necessary
+    if (m_CardType != CARD_SDHC) {
+        if (commandTransaction(CMD16, 0x00000200) != 0x00) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+    }
+
+    //The card is now initialized
+    m_Status &= ~STA_NOINIT;
+
+    //Return the disk status
+    return m_Status;
+}
+
+int SDFileSystem::disk_status()
+{
+    //Check the card socket
+    checkSocket();
+
+    //Return the disk status
+    return m_Status;
+}
+
+int SDFileSystem::disk_read(uint8_t* buffer, uint32_t sector, uint32_t count)
+{
+    //Make sure the card is initialized before proceeding
+    if (m_Status & STA_NOINIT)
+        return RES_NOTRDY;
+
+    //Read a single block, or multiple blocks
+    if (count > 1) {
+        return readBlocks((char*)buffer, sector, count) ? RES_OK : RES_ERROR;
+    } else {
+        return readBlock((char*)buffer, sector) ? RES_OK : RES_ERROR;
+    }
+}
+
+int SDFileSystem::disk_write(const uint8_t* buffer, uint32_t sector, uint32_t count)
+{
+    //Make sure the card is initialized before proceeding
+    if (m_Status & STA_NOINIT)
+        return RES_NOTRDY;
+
+    //Make sure the card isn't write protected before proceeding
+    if (m_Status & STA_PROTECT)
+        return RES_WRPRT;
+
+    //Write a single block, or multiple blocks
+    if (count > 1) {
+        return writeBlocks((const char*)buffer, sector, count) ? RES_OK : RES_ERROR;
+    } else {
+        return writeBlock((const char*)buffer, sector) ? RES_OK : RES_ERROR;
+    }
+}
+
+int SDFileSystem::disk_sync()
+{
+    //Select the card so we're forced to wait for the end of any internal write processes
+    if (select()) {
+        deselect();
+        return RES_OK;
+    } else {
+        return RES_ERROR;
+    }
+}
+
+uint32_t SDFileSystem::disk_sectors()
+{
+    //Make sure the card is initialized before proceeding
+    if (m_Status & STA_NOINIT)
+        return 0;
+
+    //Try to read the CSD register up to 3 times
+    for (int f = 0; f < 3; f++) {
+        //Select the card, and wait for ready
+        if(!select())
+            break;
+
+        //Send CMD9(0x00000000) to read the CSD register
+        if (writeCommand(CMD9, 0x00000000) == 0x00) {
+            //Read the 16B CSD data block
+            char csd[16];
+            bool success = readData(csd, 16);
+            deselect();
+            if (success) {
+                //Calculate the sector count based on the card type
+                if ((csd[0] >> 6) == 0x01) {
+                    //Calculate the sector count for a high capacity card
+                    unsigned int size = (((csd[7] & 0x3F) << 16) | (csd[8] << 8) | csd[9]) + 1;
+                    return size << 10;
+                } else {
+                    //Calculate the sector count for a standard capacity card
+                    unsigned int size = (((csd[6] & 0x03) << 10) | (csd[7] << 2) | ((csd[8] & 0xC0) >> 6)) + 1;
+                    size <<= ((((csd[9] & 0x03) << 1) | ((csd[10] & 0x80) >> 7)) + 2);
+                    size <<= (csd[5] & 0x0F);
+                    return size >> 9;
+                }
+            }
+        } else {
+            //The command failed, get out
+            break;
+        }
+    }
+
+    //The read operation failed 3 times
+    deselect();
+    return 0;
+}
+
+void SDFileSystem::onCardRemoval()
+{
+    //Check the card socket
+    checkSocket();
+}
+
+inline void SDFileSystem::checkSocket()
+{
+    //Use the card detect switch (if available) to determine if the socket is occupied
+    if (m_CdAssert != -1) {
+        if (m_Status & STA_NODISK) {
+            if (m_Cd == m_CdAssert) {
+                //The socket is now occupied
+                m_Status &= ~STA_NODISK;
+                m_CardType = CARD_UNKNOWN;
+            }
+        } else {
+            if (m_Cd != m_CdAssert) {
+                //The socket is now empty
+                m_Status |= (STA_NODISK | STA_NOINIT);
+                m_CardType = CARD_NONE;
+            }
+        }
+    }
+}
+
+inline bool SDFileSystem::waitReady(int timeout)
+{
+    char resp;
+
+    //Keep sending dummy clocks with DI held high until the card releases the DO line
+    m_Timer.start();
+    do {
+        resp = m_Spi.write(0xFF);
+    } while (resp == 0x00 && m_Timer.read_ms() < timeout);
+    m_Timer.stop();
+    m_Timer.reset();
+
+    //Return success/failure
+    return (resp > 0x00);
+}
+
+inline bool SDFileSystem::select()
+{
+    //Assert /CS
+    m_Cs = 0;
+
+    //Send 8 dummy clocks with DI held high to enable DO
+    m_Spi.write(0xFF);
+
+    //Wait for up to 500ms for the card to become ready
+    if (waitReady(500)) {
+        return true;
+    } else {
+        //We timed out, deselect and return false
+        deselect();
+        return false;
+    }
+}
+
+inline void SDFileSystem::deselect()
+{
+    //Deassert /CS
+    m_Cs = 1;
+
+    //Send 8 dummy clocks with DI held high to disable DO
+    m_Spi.write(0xFF);
+}
+
+inline char SDFileSystem::commandTransaction(char cmd, unsigned int arg, unsigned int* resp)
+{
+    //Select the card, and wait for ready
+    if(!select())
+        return 0xFF;
+
+    //Perform the command transaction
+    char token = writeCommand(cmd, arg, resp);
+
+    //Deselect the card, and return the R1 response token
+    deselect();
+    return token;
+}
+
+char SDFileSystem::writeCommand(char cmd, unsigned int arg, unsigned int* resp)
+{
+    char token;
+
+    //Try to send the command up to 3 times
+    for (int f = 0; f < 3; f++) {
+        //Send CMD55(0x00000000) prior to an application specific command
+        if (cmd == ACMD22 || cmd == ACMD23 || cmd == ACMD41 || cmd == ACMD42) {
+            token = writeCommand(CMD55, 0x00000000);
+            if (token > 0x01)
+                return token;
+
+            //Deselect and reselect the card between CMD55 and an ACMD
+            deselect();
+            if(!select())
+                return 0xFF;
+        }
+
+        //Prepare the command packet
+        char cmdPacket[6];
+        cmdPacket[0] = cmd;
+        cmdPacket[1] = arg >> 24;
+        cmdPacket[2] = arg >> 16;
+        cmdPacket[3] = arg >> 8;
+        cmdPacket[4] = arg;
+        if (m_Crc || cmd == CMD0 || cmd == CMD8)
+            cmdPacket[5] = (SDCRC::crc7(cmdPacket, 5) << 1) | 0x01;
+        else
+            cmdPacket[5] = 0x01;
+
+        //Send the command packet
+        for (int i = 0; i < 6; i++)
+            m_Spi.write(cmdPacket[i]);
+
+        //Discard the stuff byte immediately following CMD12
+        if (cmd == CMD12)
+            m_Spi.write(0xFF);
+
+        //Allow up to 8 bytes of delay for the R1 response token
+        for (int i = 0; i < 9; i++) {
+            token = m_Spi.write(0xFF);
+            if (!(token & 0x80))
+                break;
+        }
+
+        //Verify the R1 response token
+        if (token == 0xFF) {
+            //No data was received, get out early
+            break;
+        } else if (token & (1 << 3)) {
+            //There was a CRC error, try again
+            continue;
+        } else if (token > 0x01) {
+            //An error occured, get out early
+            break;
+        }
+
+        //Handle R2 and R3/R7 response tokens
+        if (cmd == CMD13 && resp != NULL) {
+            //Read the R2 response value
+            *resp = m_Spi.write(0xFF);
+        } else if ((cmd == CMD8 || cmd == CMD58) && resp != NULL) {
+            //Read the R3/R7 response value
+            *resp = (m_Spi.write(0xFF) << 24);
+            *resp |= (m_Spi.write(0xFF) << 16);
+            *resp |= (m_Spi.write(0xFF) << 8);
+            *resp |= m_Spi.write(0xFF);
+        }
+
+        //The command was successful
+        break;
+    }
+
+    //Return the R1 response token
+    return token;
+}
+
+bool SDFileSystem::readData(char* buffer, int length)
+{
+    char token;
+    unsigned short crc;
+
+    //Wait for up to 500ms for a token to arrive
+    m_Timer.start();
+    do {
+        token = m_Spi.write(0xFF);
+    } while (token == 0xFF && m_Timer.read_ms() < 500);
+    m_Timer.stop();
+    m_Timer.reset();
+
+    //Check if a valid start block token was received
+    if (token != 0xFE)
+        return false;
+
+    //Check if large frames are enabled or not
+    if (m_LargeFrames) {
+        //Switch to 16-bit frames for better performance
+        m_Spi.format(16, 0);
+
+        //Read the data block into the buffer
+        unsigned short dataWord;
+        for (int i = 0; i < length; i += 2) {
+            dataWord = m_Spi.write(0xFFFF);
+            buffer[i] = dataWord >> 8;
+            buffer[i + 1] = dataWord;
+        }
+
+        //Read the CRC16 checksum for the data block
+        crc = m_Spi.write(0xFFFF);
+
+        //Switch back to 8-bit frames
+        m_Spi.format(8, 0);
+    } else {
+        //Read the data into the buffer
+        for (int i = 0; i < length; i++)
+            buffer[i] = m_Spi.write(0xFF);
+
+        //Read the CRC16 checksum for the data block
+        crc = (m_Spi.write(0xFF) << 8);
+        crc |= m_Spi.write(0xFF);
+    }
+
+    //Return the validity of the CRC16 checksum (if enabled)
+    return (!m_Crc || crc == SDCRC::crc16(buffer, length));
+}
+
+char SDFileSystem::writeData(const char* buffer, char token)
+{
+    //Calculate the CRC16 checksum for the data block (if enabled)
+    unsigned short crc = (m_Crc) ? SDCRC::crc16(buffer, 512) : 0xFFFF;
+
+    //Wait for up to 500ms for the card to become ready
+    if (!waitReady(500))
+        return false;
+
+    //Send the start block token
+    m_Spi.write(token);
+
+    //Check if large frames are enabled or not
+    if (m_LargeFrames) {
+        //Switch to 16-bit frames for better performance
+        m_Spi.format(16, 0);
+
+        //Write the data block from the buffer
+        for (int i = 0; i < 512; i += 2)
+            m_Spi.write((buffer[i] << 8) | buffer[i + 1]);
+
+        //Send the CRC16 checksum for the data block
+        m_Spi.write(crc);
+
+        //Switch back to 8-bit frames
+        m_Spi.format(8, 0);
+    } else {
+        //Write the data block from the buffer
+        for (int i = 0; i < 512; i++)
+            m_Spi.write(buffer[i]);
+
+        //Send the CRC16 checksum for the data block
+        m_Spi.write(crc >> 8);
+        m_Spi.write(crc);
+    }
+
+    //Return the data response token
+    return (m_Spi.write(0xFF) & 0x1F);
+}
+
+inline bool SDFileSystem::readBlock(char* buffer, unsigned int lba)
+{
+    //Try to read the block up to 3 times
+    for (int f = 0; f < 3; f++) {
+        //Select the card, and wait for ready
+        if(!select())
+            break;
+
+        //Send CMD17(block) to read a single block
+        if (writeCommand(CMD17, (m_CardType == CARD_SDHC) ? lba : lba << 9) == 0x00) {
+            //Try to read the block, and deselect the card
+            bool success = readData(buffer, 512);
+            deselect();
+
+            //Return if successful
+            if (success)
+                return true;
+        } else {
+            //The command failed, get out
+            break;
+        }
+    }
+
+    //The single block read failed
+    deselect();
+    return false;
+}
+
+inline bool SDFileSystem::readBlocks(char* buffer, unsigned int lba, unsigned int count)
+{
+    //Try to read each block up to 3 times
+    for (int f = 0; f < 3;) {
+        //Select the card, and wait for ready
+        if(!select())
+            break;
+
+        //Send CMD18(block) to read multiple blocks
+        if (writeCommand(CMD18, (m_CardType == CARD_SDHC) ? lba : lba << 9) == 0x00) {
+            //Try to read all of the data blocks
+            do {
+                //Read the next block, and break on errors
+                if (!readData(buffer, 512)) {
+                    f++;
+                    break;
+                }
+
+                //Update the variables
+                lba++;
+                buffer += 512;
+                f = 0;
+            } while (--count);
+
+            //Send CMD12(0x00000000) to stop the transmission
+            if (writeCommand(CMD12, 0x00000000) != 0x00) {
+                //The command failed, get out
+                break;
+            }
+
+            //Deselect the card, and return if successful
+            deselect();
+            if (count == 0)
+                return true;
+        } else {
+            //The command failed, get out
+            break;
+        }
+    }
+
+    //The multiple block read failed
+    deselect();
+    return false;
+}
+
+inline bool SDFileSystem::writeBlock(const char* buffer, unsigned int lba)
+{
+    //Try to write the block up to 3 times
+    for (int f = 0; f < 3; f++) {
+        //Select the card, and wait for ready
+        if(!select())
+            break;
+
+        //Send CMD24(block) to write a single block
+        if (writeCommand(CMD24, (m_CardType == CARD_SDHC) ? lba : lba << 9) == 0x00) {
+            //Try to write the block, and deselect the card
+            char token = writeData(buffer, 0xFE);
+            deselect();
+
+            //Check the data response token
+            if (token == 0x0A) {
+                //A CRC error occured, try again
+                continue;
+            } else if (token == 0x0C) {
+                //A write error occured, get out
+                break;
+            }
+
+            //Send CMD13(0x00000000) to verify that the programming was successful if enabled
+            if (m_WriteValidation) {
+                unsigned int resp;
+                if (commandTransaction(CMD13, 0x00000000, &resp) != 0x00 || resp != 0x00) {
+                    //Some manner of unrecoverable write error occured during programming, get out
+                    break;
+                }
+            }
+
+            //The data was written successfully
+            return true;
+        } else {
+            //The command failed, get out
+            break;
+        }
+    }
+
+    //The single block write failed
+    deselect();
+    return false;
+}
+
+inline bool SDFileSystem::writeBlocks(const char* buffer, unsigned int lba, unsigned int count)
+{
+    char token;
+    const char* currentBuffer = buffer;
+    unsigned int currentLba = lba;
+    int currentCount = count;
+
+    //Try to write each block up to 3 times
+    for (int f = 0; f < 3;) {
+        //If this is an SD card, send ACMD23(count) to set the number of blocks to pre-erase
+        if (m_CardType != CARD_MMC) {
+            if (commandTransaction(ACMD23, currentCount) != 0x00) {
+                //The command failed, get out
+                break;
+            }
+        }
+
+        //Select the card, and wait for ready
+        if(!select())
+            break;
+
+        //Send CMD25(block) to write multiple blocks
+        if (writeCommand(CMD25, (m_CardType == CARD_SDHC) ? currentLba : currentLba << 9) == 0x00) {
+            //Try to write all of the data blocks
+            do {
+                //Write the next block and break on errors
+                token = writeData(currentBuffer, 0xFC);
+                if (token != 0x05) {
+                    f++;
+                    break;
+                }
+
+                //Update the variables
+                currentBuffer += 512;
+                f = 0;
+            } while (--currentCount);
+
+            //Wait for up to 500ms for the card to finish processing the last block
+            if (!waitReady(500))
+                break;
+
+            //Finalize the transmission
+            if (currentCount == 0) {
+                //Send the stop tran token, and deselect the card
+                m_Spi.write(0xFD);
+                deselect();
+
+                //Send CMD13(0x00000000) to verify that the programming was successful if enabled
+                if (m_WriteValidation) {
+                    unsigned int resp;
+                    if (commandTransaction(CMD13, 0x00000000, &resp) != 0x00 || resp != 0x00) {
+                        //Some manner of unrecoverable write error occured during programming, get out
+                        break;
+                    }
+                }
+
+                //The data was written successfully
+                return true;
+            } else {
+                //Send CMD12(0x00000000) to abort the transmission
+                if (writeCommand(CMD12, 0x00000000) != 0x00) {
+                    //The command failed, get out
+                    break;
+                }
+
+                //Deselect the card
+                deselect();
+
+                //Check the error token
+                if (token == 0x0A) {
+                    //Determine the number of well written blocks if possible
+                    unsigned int writtenBlocks = 0;
+                    if (m_CardType != CARD_MMC && select()) {
+                        //Send ACMD22(0x00000000) to get the number of well written blocks
+                        if (writeCommand(ACMD22, 0x00000000) == 0x00) {
+                            //Read the data
+                            char acmdData[4];
+                            if (readData(acmdData, 4)) {
+                                //Extract the number of well written blocks
+                                writtenBlocks = acmdData[0] << 24;
+                                writtenBlocks |= acmdData[1] << 16;
+                                writtenBlocks |= acmdData[2] << 8;
+                                writtenBlocks |= acmdData[3];
+                            }
+                        }
+                        deselect();
+                    }
+
+                    //Roll back the variables based on the number of well written blocks
+                    currentBuffer = buffer + (writtenBlocks << 9);
+                    currentLba = lba + writtenBlocks;
+                    currentCount = count - writtenBlocks;
+
+                    //Try again
+                    continue;
+                } else {
+                    //A write error occured, get out
+                    break;
+                }
+            }
+        } else {
+            //The command failed, get out
+            break;
+        }
+    }
+
+    //The multiple block write failed
+    deselect();
+    return false;
+}
+
+bool SDFileSystem::enableHighSpeedMode()
+{
+    //Try to issue CMD6 up to 3 times
+    for (int f = 0; f < 3; f++) {
+        //Select the card, and wait for ready
+        if(!select())
+            break;
+
+        //Send CMD6(0x80FFFFF1) to change the access mode to high speed
+        if (writeCommand(CMD6, 0x80FFFFF1) == 0x00) {
+            //Read the 64B status data block
+            char status[64];
+            bool success = readData(status, 64);
+            deselect();
+            if (success) {
+                //Return whether or not the operation was successful
+                return ((status[16] & 0x0F) == 0x1);
+            }
+        } else {
+            //The command failed, get out
+            break;
+        }
+    }
+
+    //The operation failed 3 times
+    deselect();
+    return false;
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.h	Thu Oct 13 10:51:33 2016 +0000
@@ -0,0 +1,225 @@
+/* SD/MMC File System Library
+ * Copyright (c) 2016 Neil Thiessen
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SD_FILE_SYSTEM_H
+#define SD_FILE_SYSTEM_H
+
+#include "mbed.h"
+#include "FATFileSystem.h"
+
+/** SDFileSystem class.
+ *  Used for creating a virtual file system for accessing SD/MMC cards via SPI.
+ *
+ * Example:
+ * @code
+ * #include "mbed.h"
+ * #include "SDFileSystem.h"
+ *
+ * //Create an SDFileSystem object
+ * SDFileSystem sd(p5, p6, p7, p20, "sd");
+ *
+ * int main()
+ * {
+ *     //Mount the filesystem
+ *     sd.mount();
+ *
+ *     //Perform a write test
+ *     printf("\nWriting to SD card...");
+ *     FILE *fp = fopen("/sd/sdtest.txt", "w");
+ *     if (fp != NULL) {
+ *         fprintf(fp, "We're writing to an SD card!");
+ *         fclose(fp);
+ *         printf("success!\n");
+ *     } else {
+ *         printf("failed!\n");
+ *     }
+ *
+ *     //Perform a read test
+ *     printf("Reading from SD card...");
+ *     fp = fopen("/sd/sdtest.txt", "r");
+ *     if (fp != NULL) {
+ *         char c = fgetc(fp);
+ *         if (c == 'W')
+ *             printf("success!\n");
+ *         else
+ *             printf("incorrect char (%c)!\n", c);
+ *         fclose(fp);
+ *     } else {
+ *         printf("failed!\n");
+ *     }
+ *
+ *     //Unmount the filesystem
+ *     sd.unmount();
+ * }
+ * @endcode
+ */
+class SDFileSystem : public FATFileSystem
+{
+public:
+    /** Represents the different card detect switch types
+     */
+    enum SwitchType {
+        SWITCH_NONE,    /**< No card detect switch (assumes socket is always occupied) */
+        SWITCH_POS_NO,  /**< Switch shorts to VDD when the socket is occupied (positive logic, normally open) */
+        SWITCH_POS_NC,  /**< Switch shorts to VDD when the socket is empty (positive logic, normally closed) */
+        SWITCH_NEG_NO,  /**< Switch shorts to GND when the socket is occupied (negative logic, normally open) */
+        SWITCH_NEG_NC   /**< Switch shorts to GND when the socket is empty (negative logic, normally closed) */
+    };
+
+    /** Represents the different SD/MMC card types
+     */
+    enum CardType {
+        CARD_NONE,      /**< No card is present */
+        CARD_MMC,       /**< MMC card */
+        CARD_SD,        /**< Standard capacity SD card */
+        CARD_SDHC,      /**< High capacity SD card */
+        CARD_UNKNOWN    /**< Unknown or unsupported card */
+    };
+
+    /** Create a virtual file system for accessing SD/MMC cards via SPI
+     *
+     * @param mosi The SPI data out pin.
+     * @param miso The SPI data in pin.
+     * @param sclk The SPI clock pin.
+     * @param cs The SPI chip select pin.
+     * @param name The name used to access the virtual filesystem.
+     * @param cd The card detect pin.
+     * @param cdtype The type of card detect switch.
+     * @param hz The SPI bus frequency (defaults to 1MHz).
+     */
+    SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name, PinName cd = NC, SwitchType cdtype = SWITCH_NONE, int hz = 1000000);
+
+    /** Determine whether or not a card is present
+     *
+     * @returns
+     *   'true' if a card is present,
+     *   'false' if no card is present.
+     */
+    bool card_present();
+
+    /** Get the detected SD/MMC card type
+     *
+     * @returns The detected card type as a CardType enum.
+     *
+     * @note Valid after the filesystem has been mounted.
+     */
+    SDFileSystem::CardType card_type();
+
+    /** Get whether or not CRC is enabled for commands and data
+     *
+     * @returns
+     *   'true' if CRC is enabled for commands and data,
+     *   'false' if CRC is disabled for commands and data.
+     */
+    bool crc();
+
+    /** Set whether or not CRC is enabled for commands and data
+     *
+     * @param enabled Whether or not to enable CRC for commands and data.
+     */
+    void crc(bool enabled);
+
+    /** Get whether or not 16-bit frames are enabled for data read/write operations
+     *
+     * @returns
+     *   'true' if 16-bit frames will be used during data read/write operations,
+     *   'false' if 8-bit frames will be used during data read/write operations.
+     */
+    bool large_frames();
+
+    /** Set whether or not 16-bit frames are enabled for data read/write operations
+     *
+     * @param enabled Whether or not 16-bit frames are enabled for data read/write operations.
+     */
+    void large_frames(bool enabled);
+
+    /** Get whether or not write validation is enabled for data write operations
+     *
+     * @returns
+     *   'true' if data writes will be verified using CMD13,
+     *   'false' if data writes will not be verified.
+     */
+    bool write_validation();
+
+    /** Set whether or not write validation is enabled for data write operations
+     *
+     * @param enabled Whether or not write validation is enabled for data write operations.
+     */
+    void write_validation(bool enabled);
+
+    virtual int unmount();
+    virtual int disk_initialize();
+    virtual int disk_status();
+    virtual int disk_read(uint8_t* buffer, uint32_t sector, uint32_t count);
+    virtual int disk_write(const uint8_t* buffer, uint32_t sector, uint32_t count);
+    virtual int disk_sync();
+    virtual uint32_t disk_sectors();
+
+private:
+    //Commands
+    enum Command {
+        CMD0 = (0x40 | 0),      /**< GO_IDLE_STATE */
+        CMD1 = (0x40 | 1),      /**< SEND_OP_COND */
+        CMD6 = (0x40 | 6),      /**< SWITCH_FUNC */
+        CMD8 = (0x40 | 8),      /**< SEND_IF_COND */
+        CMD9 = (0x40 | 9),      /**< SEND_CSD */
+        CMD12 = (0x40 | 12),    /**< STOP_TRANSMISSION */
+        CMD13 = (0x40 | 13),    /**< SEND_STATUS */
+        CMD16 = (0x40 | 16),    /**< SET_BLOCKLEN */
+        CMD17 = (0x40 | 17),    /**< READ_SINGLE_BLOCK */
+        CMD18 = (0x40 | 18),    /**< READ_MULTIPLE_BLOCK */
+        ACMD22 = (0x40 | 22),   /**< SEND_NUM_WR_BLOCKS */
+        ACMD23 = (0x40 | 23),   /**< SET_WR_BLK_ERASE_COUNT */
+        CMD24 = (0x40 | 24),    /**< WRITE_BLOCK */
+        CMD25 = (0x40 | 25),    /**< WRITE_MULTIPLE_BLOCK */
+        ACMD41 = (0x40 | 41),   /**< SD_SEND_OP_COND */
+        ACMD42 = (0x40 | 42),   /**< SET_CLR_CARD_DETECT */
+        CMD55 = (0x40 | 55),    /**< APP_CMD */
+        CMD58 = (0x40 | 58),    /**< READ_OCR */
+        CMD59 = (0x40 | 59)     /**< CRC_ON_OFF */
+    };
+
+    //Member variables
+    Timer m_Timer;
+    SPI m_Spi;
+    DigitalOut m_Cs;
+    InterruptIn m_Cd;
+    int m_CdAssert;
+    const int m_FREQ;
+    SDFileSystem::CardType m_CardType;
+    bool m_Crc;
+    bool m_LargeFrames;
+    bool m_WriteValidation;
+    int m_Status;
+
+    //Internal methods
+    void onCardRemoval();
+    void checkSocket();
+    bool waitReady(int timeout);
+    bool select();
+    void deselect();
+    char commandTransaction(char cmd, unsigned int arg, unsigned int* resp = NULL);
+    char writeCommand(char cmd, unsigned int arg, unsigned int* resp = NULL);
+    bool readData(char* buffer, int length);
+    char writeData(const char* buffer, char token);
+    bool readBlock(char* buffer, unsigned int lba);
+    bool readBlocks(char* buffer, unsigned int lba, unsigned int count);
+    bool writeBlock(const char* buffer, unsigned int lba);
+    bool writeBlocks(const char* buffer, unsigned int lba, unsigned int count);
+    bool enableHighSpeedMode();
+};
+
+#endif