Diff: SDFileSystem.cpp

Revision:

0:2a6d8a096edc

Child:

1:25f4ba436b81

diff -r 000000000000 -r 2a6d8a096edc SDFileSystem.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDFileSystem.cpp	Tue Jul 29 20:12:23 2014 +0000
@@ -0,0 +1,496 @@
+/* SD/MMC File System Library
+ * Copyright (c) 2014 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 "CRC7.h"
+#include "CRC16.h"
+
+SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, PinName cd, const char* name, int hz) : FATFileSystem(name), m_SPI(mosi, miso, sclk), m_CS(cs, 1), m_CD(cd)
+{
+    //Initialize the member variables
+    m_SpiFreq = hz;
+    m_Status = STA_NOINIT;
+    m_CardType = CARD_NONE;
+
+    //Configure the SPI bus
+    m_SPI.format(8, 0);
+
+    //Configure the card detect pin
+    m_CD.mode(PullUp);
+    m_CD.fall(this, &SDFileSystem::checkSocket);
+}
+
+SDFileSystem::CardType SDFileSystem::card_type()
+{
+    //Check the card socket
+    checkSocket();
+
+    //If a card is present but not initialized, initialize it
+    if (!(m_Status & STA_NODISK) && (m_Status & STA_NOINIT))
+        disk_initialize();
+
+    //Return the card type
+    return m_CardType;
+}
+
+int SDFileSystem::disk_initialize()
+{
+    char resp;
+
+    //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 100kHz for initialization
+    m_SPI.frequency(100000);
+
+    //Send 80 dummy clocks with /CS and DI held high
+    m_CS = 1;
+    for (int i = 0; i < 10; i++)
+        m_SPI.write(0xFF);
+
+    //Write CMD0(0), and check for a valid response
+    resp = writeCommand(CMD0, 0);
+    if (resp != 0x01) {
+        //Initialization failed
+        m_CardType = CARD_UNKNOWN;
+        return m_Status;
+    }
+
+    //Write CMD8(0x000001AA) to see if this is an SDCv2 card
+    resp = writeCommand(CMD8, 0x000001AA);
+    if (resp == 0x01) {
+        //This is an SDCv2 card, get the 32-bit return value and verify the voltage range/check pattern
+        if ((readReturn() & 0xFFF) != 0x1AA) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Send CMD58(0) to read the OCR, and verify that the card supports 3.2-3.3V
+        resp = writeCommand(CMD58, 0);
+        if (resp != 0x01 || !(readReturn() & (1 << 20))) {
+            //Initialization failed
+            deselect();
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Send ACMD41(0x40100000) repeatedly for up to 1 second to initialize the card
+        for (int i = 0; i < 1000; i++) {
+            resp = writeCommand(ACMD41, 0x40100000);
+            if (resp != 0x01)
+                break;
+            wait_ms(1);
+        }
+
+        //Check if the card initialized
+        if (resp != 0x00) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Send CMD58(0) to read the OCR
+        resp = writeCommand(CMD58, 0);
+        if (resp == 0x00) {
+            //Check the CCS bit to determine if this is a high capacity card
+            if (readReturn() & 0x40000000)
+                m_CardType = CARD_SDHC;
+            else
+                m_CardType = CARD_SD;
+        } 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
+        deselect();
+
+        //Send CMD58(0) to read the OCR, and verify that the card supports 3.2-3.3V
+        resp = writeCommand(CMD58, 0);
+        if (resp != 0x01 || !(readReturn() & (1 << 20))) {
+            //Initialization failed
+            deselect();
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+
+        //Try to initialize the card using ACMD41(0x00100000) for 1 second
+        for (int i = 0; i < 1000; i++) {
+            resp = writeCommand(ACMD41, 0x00100000);
+            if (resp != 0x01)
+                break;
+            wait_ms(1);
+        }
+
+        //Check if the card initialized
+        if (resp == 0x00) {
+            //This is an SDCv1 standard capacity card
+            m_CardType = CARD_SD;
+        } else {
+            //Try to initialize the card using CMD1(0x00100000) for 1 second
+            for (int i = 0; i < 1000; i++) {
+                resp = writeCommand(CMD1, 0x00100000);
+                if (resp != 0x01)
+                    break;
+                wait_ms(1);
+            }
+
+            //Check if the card initialized
+            if (resp == 0x00) {
+                //This is an MMCv3 card
+                m_CardType = CARD_MMC;
+            } else {
+                //Initialization failed
+                m_CardType = CARD_UNKNOWN;
+                return m_Status;
+            }
+        }
+    }
+
+    //Send CMD59(0x00000001) to re-enable CRC
+    resp = writeCommand(CMD59, 0x00000001);
+    if (resp != 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) {
+        resp = writeCommand(CMD16, 0x00000200);
+        if (resp != 0x00) {
+            //Initialization failed
+            m_CardType = CARD_UNKNOWN;
+            return m_Status;
+        }
+    }
+
+    //The card is now initialized
+    m_Status &= ~STA_NOINIT;
+
+    //Increase the SPI frequency to full speed (limited to 20MHz for MMC, or 25MHz for SDC)
+    if (m_CardType == CARD_MMC && m_SpiFreq > 20000000)
+        m_SPI.frequency(20000000);
+    else if (m_SpiFreq > 25000000)
+        m_SPI.frequency(25000000);
+    else
+        m_SPI.frequency(m_SpiFreq);
+
+    //Return the device status
+    return m_Status;
+}
+
+int SDFileSystem::disk_status()
+{
+    //Check if there's a card in the socket
+    checkSocket();
+
+    //Return the device status
+    return m_Status;
+}
+
+int SDFileSystem::disk_read(uint8_t* buffer, uint64_t sector)
+{
+    //Make sure the device is initialized before proceeding
+    if (m_Status & STA_NOINIT)
+        return RES_NOTRDY;
+
+    //Convert from LBA to a byte address for standard capacity cards
+    if (m_CardType != CARD_SDHC)
+        sector *= 512;
+
+    //Try to read the block up to 3 times
+    for (int i = 0; i < 3; i++) {
+        //Send CMD17(sector) to read a single block
+        char resp = writeCommand(CMD17, sector);
+        if (resp == 0x00) {
+            //Try to read the sector, and return if successful
+            if (readData((char*)buffer, 512))
+                return RES_OK;
+        } else {
+            //The command failed
+            deselect();
+            return RES_ERROR;
+        }
+    }
+
+    //The read operation failed 3 times (CRC most likely)
+    return RES_ERROR;
+}
+
+int SDFileSystem::disk_write(const uint8_t* buffer, uint64_t sector)
+{
+    //Make sure the device is initialized before proceeding
+    if (m_Status & STA_NOINIT)
+        return RES_NOTRDY;
+
+    //Make sure the device isn't write protected before proceeding
+    if (m_Status & STA_PROTECT)
+        return RES_WRPRT;
+
+    //Convert from LBA to a byte address for older cards
+    if (m_CardType != CARD_SDHC)
+        sector *= 512;
+
+    //Try to write the block up to 3 times
+    for (int i = 0; i < 3; i++) {
+        //Send CMD24(sector) to write a single block
+        if (writeCommand(CMD24, sector) == 0x00) {
+            //Wait for up to 500ms for the card to become ready
+            if (!waitReady(500)) {
+                //We timed out
+                deselect();
+                continue;
+            }
+
+            //Send the write data token
+            m_SPI.write(0xFE);
+
+            //Write the data block from the buffer
+            for (int b = 0; b < 512; b++)
+                m_SPI.write(buffer[b]);
+
+            //Calculate the CRC16 checksum for the data block and send it
+            unsigned short crc = CRC16((char*)buffer, 512);
+            m_SPI.write(crc >> 8);
+            m_SPI.write(crc);
+
+            //Receive the data response, and deselect the card
+            char resp = m_SPI.write(0xFF) & 0x1F;
+            deselect();
+
+            //Check the response
+            if (resp == 0x05)
+                return RES_OK;
+            else if (resp == 0x0D)
+                return RES_ERROR;
+        } else {
+            //The command failed
+            deselect();
+            return RES_ERROR;
+        }
+    }
+
+    //The operation either timed out 3 times, failed the CRC check 3 times, or experienced a write error
+    return RES_ERROR;
+}
+
+int SDFileSystem::disk_sync()
+{
+    //Select the card so we're forced to wait for the end of any internal write processes
+    bool ret = select();
+    deselect();
+
+    //Return success/failure
+    return (ret) ? RES_OK : RES_ERROR;
+}
+
+uint64_t SDFileSystem::disk_sectors()
+{
+    //Make sure the device is initialized before proceeding
+    if (m_Status & STA_NOINIT)
+        return 0;
+
+    //Try to read the CSD register up to 3 times
+    for (int i = 0; i < 3; i++) {
+        //Send CMD9(0) to read the CSD register
+        if (writeCommand(CMD9, 0) == 0x00) {
+            //Receive the 16B CSD data
+            char csd[16];
+            if (readData(csd, 16)) {
+                //Calculate the sector count based on the card type
+                if ((csd[0] >> 6) == 0x01) {
+                    //Calculate the sector count a high capacity card
+                    uint64_t sectors = (((csd[7] & 0x3F) << 16) | (csd[8] << 8) | csd[9]) + 1;
+                    return sectors << 10;
+                } else {
+                    //Calculate the sector count standard capacity card
+                    uint64_t sectors = (((csd[6] & 0x03) << 10) | (csd[7] << 2) | ((csd[8] & 0xC0) >> 6)) + 1;
+                    sectors <<= ((((csd[9] & 0x03) << 1) | ((csd[10] & 0x80) >> 7)) + 2);
+                    sectors <<= (csd[5] & 0x0F);
+                    return sectors >> 9;
+                }
+            }
+        } else {
+            //The command failed
+            deselect();
+            return 0;
+        }
+    }
+
+    //The read operation failed 3 times (CRC most likely)
+    return 0;
+}
+
+void SDFileSystem::checkSocket()
+{
+    //Check if a card is in the socket
+    if (m_CD) {
+        //The socket is occupied, clear the STA_NODISK flag
+        m_Status &= ~STA_NODISK;
+    } else {
+        //The socket is empty
+        m_Status |= (STA_NODISK | STA_NOINIT);
+        m_CardType = CARD_NONE;
+    }
+}
+
+inline bool SDFileSystem::waitReady(int timeout)
+{
+    //Wait for the specified timeout for the card to become ready
+    for (int i = 0; i < timeout; i++) {
+        if (m_SPI.write(0xFF) == 0xFF)
+            return true;
+        wait_ms(1);
+    }
+
+    //We timed out
+    return false;
+}
+
+inline bool SDFileSystem::select()
+{
+    //Pull /CS low
+    m_CS = 0;
+
+    //Send a dummy clock to enable DO
+    m_SPI.write(0xFF);
+
+    //Wait for up to 500ms for the card to become ready
+    if (waitReady(500))
+        return true;
+
+    //We timed out, deselect and return false
+    deselect();
+    return false;
+}
+
+inline void SDFileSystem::deselect()
+{
+    //Pull /CS high
+    m_CS = 1;
+
+    //Send a dummy byte to release DO
+    m_SPI.write(0xFF);
+}
+
+char SDFileSystem::writeCommand(char cmd, unsigned int arg)
+{
+    char resp;
+
+    //Try to send the command up to 3 times
+    for (int i = 0; i < 3; i++) {
+        //Send a CMD55 prior to an ACMD
+        if (cmd == ACMD41) {
+            resp = writeCommand(CMD55, 0);
+            if (resp > 0x01)
+                return resp;
+        }
+
+        //Select the card and wait for ready
+        if (!select())
+            return 0xFF;
+
+        //Prepare the command packet
+        char cmdPacket[6];
+        cmdPacket[0] = 0x40 | cmd;
+        cmdPacket[1] = arg >> 24;
+        cmdPacket[2] = arg >> 16;
+        cmdPacket[3] = arg >> 8;
+        cmdPacket[4] = arg;
+        cmdPacket[5] = (CRC7(cmdPacket, 5) << 1) | 0x01;
+
+        //Send the command packet
+        for (int b = 0; b < 6; b++)
+            m_SPI.write(cmdPacket[b]);
+
+        //Allow up to 10 bytes of delay for the command response
+        for (int b = 0; b < 10; b++) {
+            resp = m_SPI.write(0xFF);
+            if (!(resp & 0x80))
+                break;
+        }
+
+        //Deselect the card unless there's more data to read/write
+        if (resp == 0xFF || (resp & (1 << 3)) || !(cmd == CMD8 || cmd == CMD9 || cmd == CMD17 || cmd == CMD24 || cmd == CMD55 || cmd == CMD58))
+            deselect();
+
+        //Return the response if there were no CRC errors
+        if (resp == 0xFF || !(resp & (1 << 3)))
+            return resp;
+    }
+
+    //The command failed 3 times due to CRC errors
+    return 0xFF;
+}
+
+unsigned int SDFileSystem::readReturn()
+{
+    unsigned int ret;
+
+    //Read the 32-bit response value
+    ret = (m_SPI.write(0xFF) << 24);
+    ret |= (m_SPI.write(0xFF) << 16);
+    ret |= (m_SPI.write(0xFF) << 8);
+    ret |= m_SPI.write(0xFF);
+
+    //Deselect the card
+    deselect();
+
+    //Return the response value
+    return ret;
+}
+
+bool SDFileSystem::readData(char* buffer, int length)
+{
+    char token;
+
+    //Wait for up to 200ms for the DataStart token to arrive
+    for (int i = 0; i < 200; i++) {
+        token = m_SPI.write(0xFF);
+        if (token != 0xFF)
+            break;
+        wait_ms(1);
+    }
+
+    //Make sure the token is valid
+    if (token != 0xFE)
+        return false;
+
+    //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, and deselect the card
+    unsigned short crc = (m_SPI.write(0xFF) << 8);
+    crc |= m_SPI.write(0xFF);
+    deselect();
+
+    //Indicate whether the CRC16 checksum was valid or not
+    if (crc == CRC16(buffer, length))
+        return true;
+    else
+        return false;
+}