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Arduino-Development

/* Arduino Sd2Card Library
   Copyright (C) 2009 by William Greiman

   This file is part of the Arduino Sd2Card Library

   This Library is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with the Arduino Sd2Card Library.  If not, see
   <http://www.gnu.org/licenses/>.
*/
#define USE_SPI_LIB
#include <Arduino.h>
#include "Sd2Card.h"
//------------------------------------------------------------------------------
#ifndef SOFTWARE_SPI
#ifdef USE_SPI_LIB

  #ifndef SDCARD_SPI
    #define SDCARD_SPI SPI
  #endif

  #include <SPI.h>
  static SPISettings settings;
#endif
// functions for hardware SPI
/** Send a byte to the card */
static void spiSend(uint8_t b) {
  #ifndef USE_SPI_LIB
  SPDR = b;
  while (!(SPSR & (1 << SPIF)))
    ;
  #else
  SDCARD_SPI.transfer(b);
  #endif
}
/** Receive a byte from the card */
static  uint8_t spiRec(void) {
  #ifndef USE_SPI_LIB
  spiSend(0XFF);
  return SPDR;
  #else
  return SDCARD_SPI.transfer(0xFF);
  #endif
}
#else  // SOFTWARE_SPI
//------------------------------------------------------------------------------
/** nop to tune soft SPI timing */
#define nop asm volatile ("nop\n\t")
//------------------------------------------------------------------------------
/** Soft SPI receive */
uint8_t spiRec(void) {
  uint8_t data = 0;
  // no interrupts during byte receive - about 8 us
  cli();
  // output pin high - like sending 0XFF
  fastDigitalWrite(SPI_MOSI_PIN, HIGH);

  for (uint8_t i = 0; i < 8; i++) {
    fastDigitalWrite(SPI_SCK_PIN, HIGH);

    // adjust so SCK is nice
    nop;
    nop;

    data <<= 1;

    if (fastDigitalRead(SPI_MISO_PIN)) {
      data |= 1;
    }

    fastDigitalWrite(SPI_SCK_PIN, LOW);
  }
  // enable interrupts
  sei();
  return data;
}
//------------------------------------------------------------------------------
/** Soft SPI send */
void spiSend(uint8_t data) {
  // no interrupts during byte send - about 8 us
  cli();
  for (uint8_t i = 0; i < 8; i++) {
    fastDigitalWrite(SPI_SCK_PIN, LOW);

    fastDigitalWrite(SPI_MOSI_PIN, data & 0X80);

    data <<= 1;

    fastDigitalWrite(SPI_SCK_PIN, HIGH);
  }
  // hold SCK high for a few ns
  nop;
  nop;
  nop;
  nop;

  fastDigitalWrite(SPI_SCK_PIN, LOW);
  // enable interrupts
  sei();
}
#endif  // SOFTWARE_SPI
//------------------------------------------------------------------------------
// send command and return error code.  Return zero for OK
uint8_t Sd2Card::cardCommand(uint8_t cmd, uint32_t arg) {
  // end read if in partialBlockRead mode
  readEnd();

  // select card
  chipSelectLow();

  // wait up to 300 ms if busy
  waitNotBusy(300);

  // send command
  spiSend(cmd | 0x40);

  // send argument
  for (int8_t s = 24; s >= 0; s -= 8) {
    spiSend(arg >> s);
  }

  // send CRC
  uint8_t crc = 0XFF;
  if (cmd == CMD0) {
    crc = 0X95;  // correct crc for CMD0 with arg 0
  }
  if (cmd == CMD8) {
    crc = 0X87;  // correct crc for CMD8 with arg 0X1AA
  }
  spiSend(crc);

  // wait for response
  for (uint8_t i = 0; ((status_ = spiRec()) & 0X80) && i != 0XFF; i++)
    ;
  return status_;
}
//------------------------------------------------------------------------------
/**
   Determine the size of an SD flash memory card.

   \return The number of 512 byte data blocks in the card
           or zero if an error occurs.
*/
uint32_t Sd2Card::cardSize(void) {
  csd_t csd;
  if (!readCSD(&csd)) {
    return 0;
  }
  if (csd.v1.csd_ver == 0) {
    uint8_t read_bl_len = csd.v1.read_bl_len;
    uint16_t c_size = (csd.v1.c_size_high << 10)
                      | (csd.v1.c_size_mid << 2) | csd.v1.c_size_low;
    uint8_t c_size_mult = (csd.v1.c_size_mult_high << 1)
                          | csd.v1.c_size_mult_low;
    return (uint32_t)(c_size + 1) << (c_size_mult + read_bl_len - 7);
  } else if (csd.v2.csd_ver == 1) {
    uint32_t c_size = ((uint32_t)csd.v2.c_size_high << 16)
                      | (csd.v2.c_size_mid << 8) | csd.v2.c_size_low;
    return (c_size + 1) << 10;
  } else {
    error(SD_CARD_ERROR_BAD_CSD);
    return 0;
  }
}
//------------------------------------------------------------------------------
static uint8_t chip_select_asserted = 0;

void Sd2Card::chipSelectHigh(void) {
  digitalWrite(chipSelectPin_, HIGH);
  #ifdef USE_SPI_LIB
  if (chip_select_asserted) {
    chip_select_asserted = 0;
    SDCARD_SPI.endTransaction();
  }
  #endif
}
//------------------------------------------------------------------------------
void Sd2Card::chipSelectLow(void) {
  #ifdef USE_SPI_LIB
  if (!chip_select_asserted) {
    chip_select_asserted = 1;
    SDCARD_SPI.beginTransaction(settings);
  }
  #endif
  digitalWrite(chipSelectPin_, LOW);
}
//------------------------------------------------------------------------------
/** Erase a range of blocks.

   \param[in] firstBlock The address of the first block in the range.
   \param[in] lastBlock The address of the last block in the range.

   \note This function requests the SD card to do a flash erase for a
   range of blocks.  The data on the card after an erase operation is
   either 0 or 1, depends on the card vendor.  The card must support
   single block erase.

   \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.
*/
uint8_t Sd2Card::erase(uint32_t firstBlock, uint32_t lastBlock) {
  if (!eraseSingleBlockEnable()) {
    error(SD_CARD_ERROR_ERASE_SINGLE_BLOCK);
    goto fail;
  }
  if (type_ != SD_CARD_TYPE_SDHC) {
    firstBlock <<= 9;
    lastBlock <<= 9;
  }
  if (cardCommand(CMD32, firstBlock)
      || cardCommand(CMD33, lastBlock)
      || cardCommand(CMD38, 0)) {
    error(SD_CARD_ERROR_ERASE);
    goto fail;
  }
  if (!waitNotBusy(SD_ERASE_TIMEOUT)) {
    error(SD_CARD_ERROR_ERASE_TIMEOUT);
    goto fail;
  }
  chipSelectHigh();
  return true;

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/** Determine if card supports single block erase.

   \return The value one, true, is returned if single block erase is supported.
   The value zero, false, is returned if single block erase is not supported.
*/
uint8_t Sd2Card::eraseSingleBlockEnable(void) {
  csd_t csd;
  return readCSD(&csd) ? csd.v1.erase_blk_en : 0;
}
//------------------------------------------------------------------------------
/**
   Initialize an SD flash memory card.

   \param[in] sckRateID SPI clock rate selector. See setSckRate().
   \param[in] chipSelectPin SD chip select pin number.

   \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.  The reason for failure
   can be determined by calling errorCode() and errorData().
*/
uint8_t Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
  errorCode_ = inBlock_ = partialBlockRead_ = type_ = 0;
  chipSelectPin_ = chipSelectPin;
  // 16-bit init start time allows over a minute
  unsigned int t0 = millis();
  uint32_t arg;

  // set pin modes
  pinMode(chipSelectPin_, OUTPUT);
  digitalWrite(chipSelectPin_, HIGH);
  #ifndef USE_SPI_LIB
  pinMode(SPI_MISO_PIN, INPUT);
  pinMode(SPI_MOSI_PIN, OUTPUT);
  pinMode(SPI_SCK_PIN, OUTPUT);
  #endif

  #ifndef SOFTWARE_SPI
  #ifndef USE_SPI_LIB
  // SS must be in output mode even it is not chip select
  pinMode(SS_PIN, OUTPUT);
  digitalWrite(SS_PIN, HIGH); // disable any SPI device using hardware SS pin
  // Enable SPI, Master, clock rate f_osc/128
  SPCR = (1 << SPE) | (1 << MSTR) | (1 << SPR1) | (1 << SPR0);
  // clear double speed
  SPSR &= ~(1 << SPI2X);
  #else // USE_SPI_LIB
  SDCARD_SPI.begin();
  settings = SPISettings(250000, MSBFIRST, SPI_MODE0);
  #endif // USE_SPI_LIB
  #endif // SOFTWARE_SPI

  // must supply min of 74 clock cycles with CS high.
  #ifdef USE_SPI_LIB
  SDCARD_SPI.beginTransaction(settings);
  #endif
  for (uint8_t i = 0; i < 10; i++) {
    spiSend(0XFF);
  }
  #ifdef USE_SPI_LIB
  SDCARD_SPI.endTransaction();
  #endif

  chipSelectLow();

  // command to go idle in SPI mode
  while ((status_ = cardCommand(CMD0, 0)) != R1_IDLE_STATE) {
    unsigned int d = millis() - t0;
    if (d > SD_INIT_TIMEOUT) {
      error(SD_CARD_ERROR_CMD0);
      goto fail;
    }
  }
  // check SD version
  if ((cardCommand(CMD8, 0x1AA) & R1_ILLEGAL_COMMAND)) {
    type(SD_CARD_TYPE_SD1);
  } else {
    // only need last byte of r7 response
    for (uint8_t i = 0; i < 4; i++) {
      status_ = spiRec();
    }
    if (status_ != 0XAA) {
      error(SD_CARD_ERROR_CMD8);
      goto fail;
    }
    type(SD_CARD_TYPE_SD2);
  }
  // initialize card and send host supports SDHC if SD2
  arg = type() == SD_CARD_TYPE_SD2 ? 0X40000000 : 0;

  while ((status_ = cardAcmd(ACMD41, arg)) != R1_READY_STATE) {
    // check for timeout
    unsigned int d = millis() - t0;
    if (d > SD_INIT_TIMEOUT) {
      error(SD_CARD_ERROR_ACMD41);
      goto fail;
    }
  }
  // if SD2 read OCR register to check for SDHC card
  if (type() == SD_CARD_TYPE_SD2) {
    if (cardCommand(CMD58, 0)) {
      error(SD_CARD_ERROR_CMD58);
      goto fail;
    }
    if ((spiRec() & 0XC0) == 0XC0) {
      type(SD_CARD_TYPE_SDHC);
    }
    // discard rest of ocr - contains allowed voltage range
    for (uint8_t i = 0; i < 3; i++) {
      spiRec();
    }
  }
  chipSelectHigh();

  #ifndef SOFTWARE_SPI
  return setSckRate(sckRateID);
  #else  // SOFTWARE_SPI
  return true;
  #endif  // SOFTWARE_SPI

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/**
   Enable or disable partial block reads.

   Enabling partial block reads improves performance by allowing a block
   to be read over the SPI bus as several sub-blocks.  Errors may occur
   if the time between reads is too long since the SD card may timeout.
   The SPI SS line will be held low until the entire block is read or
   readEnd() is called.

   Use this for applications like the Adafruit Wave Shield.

   \param[in] value The value TRUE (non-zero) or FALSE (zero).)
*/
void Sd2Card::partialBlockRead(uint8_t value) {
  readEnd();
  partialBlockRead_ = value;
}
//------------------------------------------------------------------------------
/**
   Read a 512 byte block from an SD card device.

   \param[in] block Logical block to be read.
   \param[out] dst Pointer to the location that will receive the data.

   \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.
*/
uint8_t Sd2Card::readBlock(uint32_t block, uint8_t* dst) {
  return readData(block, 0, 512, dst);
}
//------------------------------------------------------------------------------
/**
   Read part of a 512 byte block from an SD card.

   \param[in] block Logical block to be read.
   \param[in] offset Number of bytes to skip at start of block
   \param[out] dst Pointer to the location that will receive the data.
   \param[in] count Number of bytes to read
   \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.
*/
uint8_t Sd2Card::readData(uint32_t block,
                          uint16_t offset, uint16_t count, uint8_t* dst) {
  if (count == 0) {
    return true;
  }
  if ((count + offset) > 512) {
    goto fail;
  }
  if (!inBlock_ || block != block_ || offset < offset_) {
    block_ = block;
    // use address if not SDHC card
    if (type() != SD_CARD_TYPE_SDHC) {
      block <<= 9;
    }
    if (cardCommand(CMD17, block)) {
      error(SD_CARD_ERROR_CMD17);
      goto fail;
    }
    if (!waitStartBlock()) {
      goto fail;
    }
    offset_ = 0;
    inBlock_ = 1;
  }

  #ifdef OPTIMIZE_HARDWARE_SPI
  // start first spi transfer
  SPDR = 0XFF;

  // skip data before offset
  for (; offset_ < offset; offset_++) {
    while (!(SPSR & (1 << SPIF)))
      ;
    SPDR = 0XFF;
  }
  // transfer data
  n = count - 1;
  for (uint16_t i = 0; i < n; i++) {
    while (!(SPSR & (1 << SPIF)))
      ;
    dst[i] = SPDR;
    SPDR = 0XFF;
  }
  // wait for last byte
  while (!(SPSR & (1 << SPIF)))
    ;
  dst[n] = SPDR;

  #else  // OPTIMIZE_HARDWARE_SPI

  // skip data before offset
  for (; offset_ < offset; offset_++) {
    spiRec();
  }
  // transfer data
  for (uint16_t i = 0; i < count; i++) {
    dst[i] = spiRec();
  }
  #endif  // OPTIMIZE_HARDWARE_SPI

  offset_ += count;
  if (!partialBlockRead_ || offset_ >= 512) {
    // read rest of data, checksum and set chip select high
    readEnd();
  }
  return true;

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/** Skip remaining data in a block when in partial block read mode. */
void Sd2Card::readEnd(void) {
  if (inBlock_) {
    // skip data and crc
    #ifdef OPTIMIZE_HARDWARE_SPI
    // optimize skip for hardware
    SPDR = 0XFF;
    while (offset_++ < 513) {
      while (!(SPSR & (1 << SPIF)))
        ;
      SPDR = 0XFF;
    }
    // wait for last crc byte
    while (!(SPSR & (1 << SPIF)))
      ;
    #else  // OPTIMIZE_HARDWARE_SPI
    while (offset_++ < 514) {
      spiRec();
    }
    #endif  // OPTIMIZE_HARDWARE_SPI
    chipSelectHigh();
    inBlock_ = 0;
  }
}
//------------------------------------------------------------------------------
/** read CID or CSR register */
uint8_t Sd2Card::readRegister(uint8_t cmd, void* buf) {
  uint8_t* dst = reinterpret_cast<uint8_t*>(buf);
  if (cardCommand(cmd, 0)) {
    error(SD_CARD_ERROR_READ_REG);
    goto fail;
  }
  if (!waitStartBlock()) {
    goto fail;
  }
  // transfer data
  for (uint16_t i = 0; i < 16; i++) {
    dst[i] = spiRec();
  }
  spiRec();  // get first crc byte
  spiRec();  // get second crc byte
  chipSelectHigh();
  return true;

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/**
   Set the SPI clock rate.

   \param[in] sckRateID A value in the range [0, 6].

   The SPI clock will be set to F_CPU/pow(2, 1 + sckRateID). The maximum
   SPI rate is F_CPU/2 for \a sckRateID = 0 and the minimum rate is F_CPU/128
   for \a scsRateID = 6.

   \return The value one, true, is returned for success and the value zero,
   false, is returned for an invalid value of \a sckRateID.
*/
uint8_t Sd2Card::setSckRate(uint8_t sckRateID) {
  if (sckRateID > 6) {
    error(SD_CARD_ERROR_SCK_RATE);
    return false;
  }
  #ifndef USE_SPI_LIB
  // see avr processor datasheet for SPI register bit definitions
  if ((sckRateID & 1) || sckRateID == 6) {
    SPSR &= ~(1 << SPI2X);
  } else {
    SPSR |= (1 << SPI2X);
  }
  SPCR &= ~((1 << SPR1) | (1 << SPR0));
  SPCR |= (sckRateID & 4 ? (1 << SPR1) : 0)
          | (sckRateID & 2 ? (1 << SPR0) : 0);
  #else // USE_SPI_LIB
  switch (sckRateID) {
    case 0:  settings = SPISettings(25000000, MSBFIRST, SPI_MODE0); break;
    case 1:  settings = SPISettings(4000000, MSBFIRST, SPI_MODE0); break;
    case 2:  settings = SPISettings(2000000, MSBFIRST, SPI_MODE0); break;
    case 3:  settings = SPISettings(1000000, MSBFIRST, SPI_MODE0); break;
    case 4:  settings = SPISettings(500000, MSBFIRST, SPI_MODE0); break;
    case 5:  settings = SPISettings(250000, MSBFIRST, SPI_MODE0); break;
    default: settings = SPISettings(125000, MSBFIRST, SPI_MODE0);
  }
  #endif // USE_SPI_LIB
  return true;
}
#ifdef USE_SPI_LIB
//------------------------------------------------------------------------------
// set the SPI clock frequency
uint8_t Sd2Card::setSpiClock(uint32_t clock) {
  settings = SPISettings(clock, MSBFIRST, SPI_MODE0);
  return true;
}
#endif
//------------------------------------------------------------------------------
// wait for card to go not busy
uint8_t Sd2Card::waitNotBusy(unsigned int timeoutMillis) {
  unsigned int t0 = millis();
  unsigned int d;
  do {
    if (spiRec() == 0XFF) {
      return true;
    }
    d = millis() - t0;
  } while (d < timeoutMillis);
  return false;
}
//------------------------------------------------------------------------------
/** Wait for start block token */
uint8_t Sd2Card::waitStartBlock(void) {
  unsigned int t0 = millis();
  while ((status_ = spiRec()) == 0XFF) {
    unsigned int d = millis() - t0;
    if (d > SD_READ_TIMEOUT) {
      error(SD_CARD_ERROR_READ_TIMEOUT);
      goto fail;
    }
  }
  if (status_ != DATA_START_BLOCK) {
    error(SD_CARD_ERROR_READ);
    goto fail;
  }
  return true;

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/**
   Writes a 512 byte block to an SD card.

   \param[in] blockNumber Logical block to be written.
   \param[in] src Pointer to the location of the data to be written.
   \param[in] blocking If the write should be blocking.
   \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.
*/
uint8_t Sd2Card::writeBlock(uint32_t blockNumber, const uint8_t* src, uint8_t blocking) {
  #if SD_PROTECT_BLOCK_ZERO
  // don't allow write to first block
  if (blockNumber == 0) {
    error(SD_CARD_ERROR_WRITE_BLOCK_ZERO);
    goto fail;
  }
  #endif  // SD_PROTECT_BLOCK_ZERO

  // use address if not SDHC card
  if (type() != SD_CARD_TYPE_SDHC) {
    blockNumber <<= 9;
  }
  if (cardCommand(CMD24, blockNumber)) {
    error(SD_CARD_ERROR_CMD24);
    goto fail;
  }
  if (!writeData(DATA_START_BLOCK, src)) {
    goto fail;
  }
  if (blocking) {
    // wait for flash programming to complete
    if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
      error(SD_CARD_ERROR_WRITE_TIMEOUT);
      goto fail;
    }
    // response is r2 so get and check two bytes for nonzero
    if (cardCommand(CMD13, 0) || spiRec()) {
      error(SD_CARD_ERROR_WRITE_PROGRAMMING);
      goto fail;
    }
  }
  chipSelectHigh();
  return true;

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/** Write one data block in a multiple block write sequence */
uint8_t Sd2Card::writeData(const uint8_t* src) {
  // wait for previous write to finish
  if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
    error(SD_CARD_ERROR_WRITE_MULTIPLE);
    chipSelectHigh();
    return false;
  }
  return writeData(WRITE_MULTIPLE_TOKEN, src);
}
//------------------------------------------------------------------------------
// send one block of data for write block or write multiple blocks
uint8_t Sd2Card::writeData(uint8_t token, const uint8_t* src) {
  #ifdef OPTIMIZE_HARDWARE_SPI

  // send data - optimized loop
  SPDR = token;

  // send two byte per iteration
  for (uint16_t i = 0; i < 512; i += 2) {
    while (!(SPSR & (1 << SPIF)))
      ;
    SPDR = src[i];
    while (!(SPSR & (1 << SPIF)))
      ;
    SPDR = src[i + 1];
  }

  // wait for last data byte
  while (!(SPSR & (1 << SPIF)))
    ;

  #else  // OPTIMIZE_HARDWARE_SPI
  spiSend(token);
  for (uint16_t i = 0; i < 512; i++) {
    spiSend(src[i]);
  }
  #endif  // OPTIMIZE_HARDWARE_SPI
  spiSend(0xff);  // dummy crc
  spiSend(0xff);  // dummy crc

  status_ = spiRec();
  if ((status_ & DATA_RES_MASK) != DATA_RES_ACCEPTED) {
    error(SD_CARD_ERROR_WRITE);
    chipSelectHigh();
    return false;
  }
  return true;
}
//------------------------------------------------------------------------------
/** Start a write multiple blocks sequence.

   \param[in] blockNumber Address of first block in sequence.
   \param[in] eraseCount The number of blocks to be pre-erased.

   \note This function is used with writeData() and writeStop()
   for optimized multiple block writes.

   \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.
*/
uint8_t Sd2Card::writeStart(uint32_t blockNumber, uint32_t eraseCount) {
  #if SD_PROTECT_BLOCK_ZERO
  // don't allow write to first block
  if (blockNumber == 0) {
    error(SD_CARD_ERROR_WRITE_BLOCK_ZERO);
    goto fail;
  }
  #endif  // SD_PROTECT_BLOCK_ZERO
  // send pre-erase count
  if (cardAcmd(ACMD23, eraseCount)) {
    error(SD_CARD_ERROR_ACMD23);
    goto fail;
  }
  // use address if not SDHC card
  if (type() != SD_CARD_TYPE_SDHC) {
    blockNumber <<= 9;
  }
  if (cardCommand(CMD25, blockNumber)) {
    error(SD_CARD_ERROR_CMD25);
    goto fail;
  }
  return true;

fail:
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/** End a write multiple blocks sequence.

  \return The value one, true, is returned for success and
   the value zero, false, is returned for failure.
*/
uint8_t Sd2Card::writeStop(void) {
  if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
    goto fail;
  }
  spiSend(STOP_TRAN_TOKEN);
  if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
    goto fail;
  }
  chipSelectHigh();
  return true;

fail:
  error(SD_CARD_ERROR_STOP_TRAN);
  chipSelectHigh();
  return false;
}
//------------------------------------------------------------------------------
/** Check if the SD card is busy

  \return The value one, true, is returned when is busy and
   the value zero, false, is returned for when is NOT busy.
*/
uint8_t Sd2Card::isBusy(void) {
  chipSelectLow();
  byte b = spiRec();
  chipSelectHigh();

  return (b != 0XFF);
}

	/* Arduino Sd2Card Library
	Copyright (C) 2009 by William Greiman

	This file is part of the Arduino Sd2Card Library

	This Library is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This Library is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with the Arduino Sd2Card Library. If not, see
	<http://www.gnu.org/licenses/>.
	*/
	#define USE_SPI_LIB
	#include <Arduino.h>
	#include "Sd2Card.h"
	//------------------------------------------------------------------------------
	#ifndef SOFTWARE_SPI
	#ifdef USE_SPI_LIB

	#ifndef SDCARD_SPI
	#define SDCARD_SPI SPI
	#endif

	#include <SPI.h>
	static SPISettings settings;
	#endif
	// functions for hardware SPI
	/** Send a byte to the card */
	static void spiSend(uint8_t b) {
	#ifndef USE_SPI_LIB
	SPDR = b;
	while (!(SPSR & (1 << SPIF)))
	;
	#else
	SDCARD_SPI.transfer(b);
	#endif
	}
	/** Receive a byte from the card */
	static uint8_t spiRec(void) {
	#ifndef USE_SPI_LIB
	spiSend(0XFF);
	return SPDR;
	#else
	return SDCARD_SPI.transfer(0xFF);
	#endif
	}
	#else // SOFTWARE_SPI
	//------------------------------------------------------------------------------
	/** nop to tune soft SPI timing */
	#define nop asm volatile ("nop\n\t")
	//------------------------------------------------------------------------------
	/** Soft SPI receive */
	uint8_t spiRec(void) {
	uint8_t data = 0;
	// no interrupts during byte receive - about 8 us
	cli();
	// output pin high - like sending 0XFF
	fastDigitalWrite(SPI_MOSI_PIN, HIGH);

	for (uint8_t i = 0; i < 8; i++) {
	fastDigitalWrite(SPI_SCK_PIN, HIGH);

	// adjust so SCK is nice
	nop;
	nop;

	data <<= 1;

	if (fastDigitalRead(SPI_MISO_PIN)) {
	data \|= 1;
	}

	fastDigitalWrite(SPI_SCK_PIN, LOW);
	}
	// enable interrupts
	sei();
	return data;
	}
	//------------------------------------------------------------------------------
	/** Soft SPI send */
	void spiSend(uint8_t data) {
	// no interrupts during byte send - about 8 us
	cli();
	for (uint8_t i = 0; i < 8; i++) {
	fastDigitalWrite(SPI_SCK_PIN, LOW);

	fastDigitalWrite(SPI_MOSI_PIN, data & 0X80);

	data <<= 1;

	fastDigitalWrite(SPI_SCK_PIN, HIGH);
	}
	// hold SCK high for a few ns
	nop;
	nop;
	nop;
	nop;

	fastDigitalWrite(SPI_SCK_PIN, LOW);
	// enable interrupts
	sei();
	}
	#endif // SOFTWARE_SPI
	//------------------------------------------------------------------------------
	// send command and return error code. Return zero for OK
	uint8_t Sd2Card::cardCommand(uint8_t cmd, uint32_t arg) {
	// end read if in partialBlockRead mode
	readEnd();

	// select card
	chipSelectLow();

	// wait up to 300 ms if busy
	waitNotBusy(300);

	// send command
	spiSend(cmd \| 0x40);

	// send argument
	for (int8_t s = 24; s >= 0; s -= 8) {
	spiSend(arg >> s);
	}

	// send CRC
	uint8_t crc = 0XFF;
	if (cmd == CMD0) {
	crc = 0X95; // correct crc for CMD0 with arg 0
	}
	if (cmd == CMD8) {
	crc = 0X87; // correct crc for CMD8 with arg 0X1AA
	}
	spiSend(crc);

	// wait for response
	for (uint8_t i = 0; ((status_ = spiRec()) & 0X80) && i != 0XFF; i++)
	;
	return status_;
	}
	//------------------------------------------------------------------------------
	/**
	Determine the size of an SD flash memory card.

	\return The number of 512 byte data blocks in the card
	or zero if an error occurs.
	*/
	uint32_t Sd2Card::cardSize(void) {
	csd_t csd;
	if (!readCSD(&csd)) {
	return 0;
	}
	if (csd.v1.csd_ver == 0) {
	uint8_t read_bl_len = csd.v1.read_bl_len;
	uint16_t c_size = (csd.v1.c_size_high << 10)
	\| (csd.v1.c_size_mid << 2) \| csd.v1.c_size_low;
	uint8_t c_size_mult = (csd.v1.c_size_mult_high << 1)
	\| csd.v1.c_size_mult_low;
	return (uint32_t)(c_size + 1) << (c_size_mult + read_bl_len - 7);
	} else if (csd.v2.csd_ver == 1) {
	uint32_t c_size = ((uint32_t)csd.v2.c_size_high << 16)
	\| (csd.v2.c_size_mid << 8) \| csd.v2.c_size_low;
	return (c_size + 1) << 10;
	} else {
	error(SD_CARD_ERROR_BAD_CSD);
	return 0;
	}
	}
	//------------------------------------------------------------------------------
	static uint8_t chip_select_asserted = 0;

	void Sd2Card::chipSelectHigh(void) {
	digitalWrite(chipSelectPin_, HIGH);
	#ifdef USE_SPI_LIB
	if (chip_select_asserted) {
	chip_select_asserted = 0;
	SDCARD_SPI.endTransaction();
	}
	#endif
	}
	//------------------------------------------------------------------------------
	void Sd2Card::chipSelectLow(void) {
	#ifdef USE_SPI_LIB
	if (!chip_select_asserted) {
	chip_select_asserted = 1;
	SDCARD_SPI.beginTransaction(settings);
	}
	#endif
	digitalWrite(chipSelectPin_, LOW);
	}
	//------------------------------------------------------------------------------
	/** Erase a range of blocks.

	\param[in] firstBlock The address of the first block in the range.
	\param[in] lastBlock The address of the last block in the range.

	\note This function requests the SD card to do a flash erase for a
	range of blocks. The data on the card after an erase operation is
	either 0 or 1, depends on the card vendor. The card must support
	single block erase.

	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure.
	*/
	uint8_t Sd2Card::erase(uint32_t firstBlock, uint32_t lastBlock) {
	if (!eraseSingleBlockEnable()) {
	error(SD_CARD_ERROR_ERASE_SINGLE_BLOCK);
	goto fail;
	}
	if (type_ != SD_CARD_TYPE_SDHC) {
	firstBlock <<= 9;
	lastBlock <<= 9;
	}
	if (cardCommand(CMD32, firstBlock)
	\|\| cardCommand(CMD33, lastBlock)
	\|\| cardCommand(CMD38, 0)) {
	error(SD_CARD_ERROR_ERASE);
	goto fail;
	}
	if (!waitNotBusy(SD_ERASE_TIMEOUT)) {
	error(SD_CARD_ERROR_ERASE_TIMEOUT);
	goto fail;
	}
	chipSelectHigh();
	return true;

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/** Determine if card supports single block erase.

	\return The value one, true, is returned if single block erase is supported.
	The value zero, false, is returned if single block erase is not supported.
	*/
	uint8_t Sd2Card::eraseSingleBlockEnable(void) {
	csd_t csd;
	return readCSD(&csd) ? csd.v1.erase_blk_en : 0;
	}
	//------------------------------------------------------------------------------
	/**
	Initialize an SD flash memory card.

	\param[in] sckRateID SPI clock rate selector. See setSckRate().
	\param[in] chipSelectPin SD chip select pin number.

	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure. The reason for failure
	can be determined by calling errorCode() and errorData().
	*/
	uint8_t Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
	errorCode_ = inBlock_ = partialBlockRead_ = type_ = 0;
	chipSelectPin_ = chipSelectPin;
	// 16-bit init start time allows over a minute
	unsigned int t0 = millis();
	uint32_t arg;

	// set pin modes
	pinMode(chipSelectPin_, OUTPUT);
	digitalWrite(chipSelectPin_, HIGH);
	#ifndef USE_SPI_LIB
	pinMode(SPI_MISO_PIN, INPUT);
	pinMode(SPI_MOSI_PIN, OUTPUT);
	pinMode(SPI_SCK_PIN, OUTPUT);
	#endif

	#ifndef SOFTWARE_SPI
	#ifndef USE_SPI_LIB
	// SS must be in output mode even it is not chip select
	pinMode(SS_PIN, OUTPUT);
	digitalWrite(SS_PIN, HIGH); // disable any SPI device using hardware SS pin
	// Enable SPI, Master, clock rate f_osc/128
	SPCR = (1 << SPE) \| (1 << MSTR) \| (1 << SPR1) \| (1 << SPR0);
	// clear double speed
	SPSR &= ~(1 << SPI2X);
	#else // USE_SPI_LIB
	SDCARD_SPI.begin();
	settings = SPISettings(250000, MSBFIRST, SPI_MODE0);
	#endif // USE_SPI_LIB
	#endif // SOFTWARE_SPI

	// must supply min of 74 clock cycles with CS high.
	#ifdef USE_SPI_LIB
	SDCARD_SPI.beginTransaction(settings);
	#endif
	for (uint8_t i = 0; i < 10; i++) {
	spiSend(0XFF);
	}
	#ifdef USE_SPI_LIB
	SDCARD_SPI.endTransaction();
	#endif

	chipSelectLow();

	// command to go idle in SPI mode
	while ((status_ = cardCommand(CMD0, 0)) != R1_IDLE_STATE) {
	unsigned int d = millis() - t0;
	if (d > SD_INIT_TIMEOUT) {
	error(SD_CARD_ERROR_CMD0);
	goto fail;
	}
	}
	// check SD version
	if ((cardCommand(CMD8, 0x1AA) & R1_ILLEGAL_COMMAND)) {
	type(SD_CARD_TYPE_SD1);
	} else {
	// only need last byte of r7 response
	for (uint8_t i = 0; i < 4; i++) {
	status_ = spiRec();
	}
	if (status_ != 0XAA) {
	error(SD_CARD_ERROR_CMD8);
	goto fail;
	}
	type(SD_CARD_TYPE_SD2);
	}
	// initialize card and send host supports SDHC if SD2
	arg = type() == SD_CARD_TYPE_SD2 ? 0X40000000 : 0;

	while ((status_ = cardAcmd(ACMD41, arg)) != R1_READY_STATE) {
	// check for timeout
	unsigned int d = millis() - t0;
	if (d > SD_INIT_TIMEOUT) {
	error(SD_CARD_ERROR_ACMD41);
	goto fail;
	}
	}
	// if SD2 read OCR register to check for SDHC card
	if (type() == SD_CARD_TYPE_SD2) {
	if (cardCommand(CMD58, 0)) {
	error(SD_CARD_ERROR_CMD58);
	goto fail;
	}
	if ((spiRec() & 0XC0) == 0XC0) {
	type(SD_CARD_TYPE_SDHC);
	}
	// discard rest of ocr - contains allowed voltage range
	for (uint8_t i = 0; i < 3; i++) {
	spiRec();
	}
	}
	chipSelectHigh();

	#ifndef SOFTWARE_SPI
	return setSckRate(sckRateID);
	#else // SOFTWARE_SPI
	return true;
	#endif // SOFTWARE_SPI

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/**
	Enable or disable partial block reads.

	Enabling partial block reads improves performance by allowing a block
	to be read over the SPI bus as several sub-blocks. Errors may occur
	if the time between reads is too long since the SD card may timeout.
	The SPI SS line will be held low until the entire block is read or
	readEnd() is called.

	Use this for applications like the Adafruit Wave Shield.

	\param[in] value The value TRUE (non-zero) or FALSE (zero).)
	*/
	void Sd2Card::partialBlockRead(uint8_t value) {
	readEnd();
	partialBlockRead_ = value;
	}
	//------------------------------------------------------------------------------
	/**
	Read a 512 byte block from an SD card device.

	\param[in] block Logical block to be read.
	\param[out] dst Pointer to the location that will receive the data.

	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure.
	*/
	uint8_t Sd2Card::readBlock(uint32_t block, uint8_t* dst) {
	return readData(block, 0, 512, dst);
	}
	//------------------------------------------------------------------------------
	/**
	Read part of a 512 byte block from an SD card.

	\param[in] block Logical block to be read.
	\param[in] offset Number of bytes to skip at start of block
	\param[out] dst Pointer to the location that will receive the data.
	\param[in] count Number of bytes to read
	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure.
	*/
	uint8_t Sd2Card::readData(uint32_t block,
	uint16_t offset, uint16_t count, uint8_t* dst) {
	if (count == 0) {
	return true;
	}
	if ((count + offset) > 512) {
	goto fail;
	}
	if (!inBlock_ \|\| block != block_ \|\| offset < offset_) {
	block_ = block;
	// use address if not SDHC card
	if (type() != SD_CARD_TYPE_SDHC) {
	block <<= 9;
	}
	if (cardCommand(CMD17, block)) {
	error(SD_CARD_ERROR_CMD17);
	goto fail;
	}
	if (!waitStartBlock()) {
	goto fail;
	}
	offset_ = 0;
	inBlock_ = 1;
	}

	#ifdef OPTIMIZE_HARDWARE_SPI
	// start first spi transfer
	SPDR = 0XFF;

	// skip data before offset
	for (; offset_ < offset; offset_++) {
	while (!(SPSR & (1 << SPIF)))
	;
	SPDR = 0XFF;
	}
	// transfer data
	n = count - 1;
	for (uint16_t i = 0; i < n; i++) {
	while (!(SPSR & (1 << SPIF)))
	;
	dst[i] = SPDR;
	SPDR = 0XFF;
	}
	// wait for last byte
	while (!(SPSR & (1 << SPIF)))
	;
	dst[n] = SPDR;

	#else // OPTIMIZE_HARDWARE_SPI

	// skip data before offset
	for (; offset_ < offset; offset_++) {
	spiRec();
	}
	// transfer data
	for (uint16_t i = 0; i < count; i++) {
	dst[i] = spiRec();
	}
	#endif // OPTIMIZE_HARDWARE_SPI

	offset_ += count;
	if (!partialBlockRead_ \|\| offset_ >= 512) {
	// read rest of data, checksum and set chip select high
	readEnd();
	}
	return true;

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/** Skip remaining data in a block when in partial block read mode. */
	void Sd2Card::readEnd(void) {
	if (inBlock_) {
	// skip data and crc
	#ifdef OPTIMIZE_HARDWARE_SPI
	// optimize skip for hardware
	SPDR = 0XFF;
	while (offset_++ < 513) {
	while (!(SPSR & (1 << SPIF)))
	;
	SPDR = 0XFF;
	}
	// wait for last crc byte
	while (!(SPSR & (1 << SPIF)))
	;
	#else // OPTIMIZE_HARDWARE_SPI
	while (offset_++ < 514) {
	spiRec();
	}
	#endif // OPTIMIZE_HARDWARE_SPI
	chipSelectHigh();
	inBlock_ = 0;
	}
	}
	//------------------------------------------------------------------------------
	/** read CID or CSR register */
	uint8_t Sd2Card::readRegister(uint8_t cmd, void* buf) {
	uint8_t* dst = reinterpret_cast<uint8_t*>(buf);
	if (cardCommand(cmd, 0)) {
	error(SD_CARD_ERROR_READ_REG);
	goto fail;
	}
	if (!waitStartBlock()) {
	goto fail;
	}
	// transfer data
	for (uint16_t i = 0; i < 16; i++) {
	dst[i] = spiRec();
	}
	spiRec(); // get first crc byte
	spiRec(); // get second crc byte
	chipSelectHigh();
	return true;

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/**
	Set the SPI clock rate.

	\param[in] sckRateID A value in the range [0, 6].

	The SPI clock will be set to F_CPU/pow(2, 1 + sckRateID). The maximum
	SPI rate is F_CPU/2 for \a sckRateID = 0 and the minimum rate is F_CPU/128
	for \a scsRateID = 6.

	\return The value one, true, is returned for success and the value zero,
	false, is returned for an invalid value of \a sckRateID.
	*/
	uint8_t Sd2Card::setSckRate(uint8_t sckRateID) {
	if (sckRateID > 6) {
	error(SD_CARD_ERROR_SCK_RATE);
	return false;
	}
	#ifndef USE_SPI_LIB
	// see avr processor datasheet for SPI register bit definitions
	if ((sckRateID & 1) \|\| sckRateID == 6) {
	SPSR &= ~(1 << SPI2X);
	} else {
	SPSR \|= (1 << SPI2X);
	}
	SPCR &= ~((1 << SPR1) \| (1 << SPR0));
	SPCR \|= (sckRateID & 4 ? (1 << SPR1) : 0)
	\| (sckRateID & 2 ? (1 << SPR0) : 0);
	#else // USE_SPI_LIB
	switch (sckRateID) {
	case 0: settings = SPISettings(25000000, MSBFIRST, SPI_MODE0); break;
	case 1: settings = SPISettings(4000000, MSBFIRST, SPI_MODE0); break;
	case 2: settings = SPISettings(2000000, MSBFIRST, SPI_MODE0); break;
	case 3: settings = SPISettings(1000000, MSBFIRST, SPI_MODE0); break;
	case 4: settings = SPISettings(500000, MSBFIRST, SPI_MODE0); break;
	case 5: settings = SPISettings(250000, MSBFIRST, SPI_MODE0); break;
	default: settings = SPISettings(125000, MSBFIRST, SPI_MODE0);
	}
	#endif // USE_SPI_LIB
	return true;
	}
	#ifdef USE_SPI_LIB
	//------------------------------------------------------------------------------
	// set the SPI clock frequency
	uint8_t Sd2Card::setSpiClock(uint32_t clock) {
	settings = SPISettings(clock, MSBFIRST, SPI_MODE0);
	return true;
	}
	#endif
	//------------------------------------------------------------------------------
	// wait for card to go not busy
	uint8_t Sd2Card::waitNotBusy(unsigned int timeoutMillis) {
	unsigned int t0 = millis();
	unsigned int d;
	do {
	if (spiRec() == 0XFF) {
	return true;
	}
	d = millis() - t0;
	} while (d < timeoutMillis);
	return false;
	}
	//------------------------------------------------------------------------------
	/** Wait for start block token */
	uint8_t Sd2Card::waitStartBlock(void) {
	unsigned int t0 = millis();
	while ((status_ = spiRec()) == 0XFF) {
	unsigned int d = millis() - t0;
	if (d > SD_READ_TIMEOUT) {
	error(SD_CARD_ERROR_READ_TIMEOUT);
	goto fail;
	}
	}
	if (status_ != DATA_START_BLOCK) {
	error(SD_CARD_ERROR_READ);
	goto fail;
	}
	return true;

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/**
	Writes a 512 byte block to an SD card.

	\param[in] blockNumber Logical block to be written.
	\param[in] src Pointer to the location of the data to be written.
	\param[in] blocking If the write should be blocking.
	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure.
	*/
	uint8_t Sd2Card::writeBlock(uint32_t blockNumber, const uint8_t* src, uint8_t blocking) {
	#if SD_PROTECT_BLOCK_ZERO
	// don't allow write to first block
	if (blockNumber == 0) {
	error(SD_CARD_ERROR_WRITE_BLOCK_ZERO);
	goto fail;
	}
	#endif // SD_PROTECT_BLOCK_ZERO

	// use address if not SDHC card
	if (type() != SD_CARD_TYPE_SDHC) {
	blockNumber <<= 9;
	}
	if (cardCommand(CMD24, blockNumber)) {
	error(SD_CARD_ERROR_CMD24);
	goto fail;
	}
	if (!writeData(DATA_START_BLOCK, src)) {
	goto fail;
	}
	if (blocking) {
	// wait for flash programming to complete
	if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
	error(SD_CARD_ERROR_WRITE_TIMEOUT);
	goto fail;
	}
	// response is r2 so get and check two bytes for nonzero
	if (cardCommand(CMD13, 0) \|\| spiRec()) {
	error(SD_CARD_ERROR_WRITE_PROGRAMMING);
	goto fail;
	}
	}
	chipSelectHigh();
	return true;

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/** Write one data block in a multiple block write sequence */
	uint8_t Sd2Card::writeData(const uint8_t* src) {
	// wait for previous write to finish
	if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
	error(SD_CARD_ERROR_WRITE_MULTIPLE);
	chipSelectHigh();
	return false;
	}
	return writeData(WRITE_MULTIPLE_TOKEN, src);
	}
	//------------------------------------------------------------------------------
	// send one block of data for write block or write multiple blocks
	uint8_t Sd2Card::writeData(uint8_t token, const uint8_t* src) {
	#ifdef OPTIMIZE_HARDWARE_SPI

	// send data - optimized loop
	SPDR = token;

	// send two byte per iteration
	for (uint16_t i = 0; i < 512; i += 2) {
	while (!(SPSR & (1 << SPIF)))
	;
	SPDR = src[i];
	while (!(SPSR & (1 << SPIF)))
	;
	SPDR = src[i + 1];
	}

	// wait for last data byte
	while (!(SPSR & (1 << SPIF)))
	;

	#else // OPTIMIZE_HARDWARE_SPI
	spiSend(token);
	for (uint16_t i = 0; i < 512; i++) {
	spiSend(src[i]);
	}
	#endif // OPTIMIZE_HARDWARE_SPI
	spiSend(0xff); // dummy crc
	spiSend(0xff); // dummy crc

	status_ = spiRec();
	if ((status_ & DATA_RES_MASK) != DATA_RES_ACCEPTED) {
	error(SD_CARD_ERROR_WRITE);
	chipSelectHigh();
	return false;
	}
	return true;
	}
	//------------------------------------------------------------------------------
	/** Start a write multiple blocks sequence.

	\param[in] blockNumber Address of first block in sequence.
	\param[in] eraseCount The number of blocks to be pre-erased.

	\note This function is used with writeData() and writeStop()
	for optimized multiple block writes.

	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure.
	*/
	uint8_t Sd2Card::writeStart(uint32_t blockNumber, uint32_t eraseCount) {
	#if SD_PROTECT_BLOCK_ZERO
	// don't allow write to first block
	if (blockNumber == 0) {
	error(SD_CARD_ERROR_WRITE_BLOCK_ZERO);
	goto fail;
	}
	#endif // SD_PROTECT_BLOCK_ZERO
	// send pre-erase count
	if (cardAcmd(ACMD23, eraseCount)) {
	error(SD_CARD_ERROR_ACMD23);
	goto fail;
	}
	// use address if not SDHC card
	if (type() != SD_CARD_TYPE_SDHC) {
	blockNumber <<= 9;
	}
	if (cardCommand(CMD25, blockNumber)) {
	error(SD_CARD_ERROR_CMD25);
	goto fail;
	}
	return true;

	fail:
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/** End a write multiple blocks sequence.

	\return The value one, true, is returned for success and
	the value zero, false, is returned for failure.
	*/
	uint8_t Sd2Card::writeStop(void) {
	if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
	goto fail;
	}
	spiSend(STOP_TRAN_TOKEN);
	if (!waitNotBusy(SD_WRITE_TIMEOUT)) {
	goto fail;
	}
	chipSelectHigh();
	return true;

	fail:
	error(SD_CARD_ERROR_STOP_TRAN);
	chipSelectHigh();
	return false;
	}
	//------------------------------------------------------------------------------
	/** Check if the SD card is busy

	\return The value one, true, is returned when is busy and
	the value zero, false, is returned for when is NOT busy.
	*/
	uint8_t Sd2Card::isBusy(void) {
	chipSelectLow();
	byte b = spiRec();
	chipSelectHigh();

	return (b != 0XFF);
	}