diff --git a/storage/blockdevice/COMPONENT_SD/include/SD/SDBlockDevice.h b/storage/blockdevice/COMPONENT_SD/include/SD/SDBlockDevice.h
index a309240..46a427e 100644
--- a/storage/blockdevice/COMPONENT_SD/include/SD/SDBlockDevice.h
+++ b/storage/blockdevice/COMPONENT_SD/include/SD/SDBlockDevice.h
@@ -58,12 +58,12 @@
  */
 class SDBlockDevice : public mbed::BlockDevice {
 public:
-    /** Creates an SDBlockDevice on a SPI bus specified by pins (using dynamic pin-map)
+    /** Creates an SDBlockDevice on a SPI bus specified by pins (using dynamic pin-map).
      *
      *  @param mosi     SPI master out, slave in pin
      *  @param miso     SPI master in, slave out pin
      *  @param sclk     SPI clock pin
-     *  @param cs       SPI chip select pin
+     *  @param cs       SPI chip select pin.   This constructor needs a *hardware* chip select pin.
      *  @param hz       Clock speed of the SPI bus (defaults to 1MHz)
      *  @param crc_on   Enable cyclic redundancy check (defaults to disabled)
      */
@@ -74,13 +74,47 @@
                   uint64_t hz = MBED_CONF_SD_TRX_FREQUENCY,
                   bool crc_on = MBED_CONF_SD_CRC_ENABLED);
 
-    /** Creates an SDBlockDevice on a SPI bus specified by pins (using static pin-map)
+    /** Creates an SDBlockDevice on a SPI bus specified by pins (using dynamic pin-map).
+     * This version creates an SPI object that uses GPIO for its chip select line instead of
+     * a dedicated hardware CS pin.
+     *
+     *  @param mosi     SPI master out, slave in pin
+     *  @param miso     SPI master in, slave out pin
+     *  @param sclk     SPI clock pin
+     *  @param cs       SPI chip select pin.  May be any GPIO pin.
+     *  @param hz       Clock speed of the SPI bus (defaults to 1MHz)
+     *  @param crc_on   Enable cyclic redundancy check (defaults to disabled)
+     */
+    SDBlockDevice(mbed::use_gpio_ssel_t,
+                  PinName mosi = MBED_CONF_SD_SPI_MOSI,
+                  PinName miso = MBED_CONF_SD_SPI_MISO,
+                  PinName sclk = MBED_CONF_SD_SPI_CLK,
+                  PinName cs = MBED_CONF_SD_SPI_CS,
+                  uint64_t hz = MBED_CONF_SD_TRX_FREQUENCY,
+                  bool crc_on = MBED_CONF_SD_CRC_ENABLED);
+
+
+    /** Creates an SDBlockDevice on a SPI bus specified by pins (using static pin-map).
+     * This version needs a pinmap containing a hardware chip select pin.
      *
      *  @param spi_pinmap Static SPI pin-map
      *  @param hz         Clock speed of the SPI bus (defaults to 1MHz)
      *  @param crc_on     Enable cyclic redundancy check (defaults to disabled)
      */
     SDBlockDevice(const spi_pinmap_t &spi_pinmap,
+                  uint64_t hz = MBED_CONF_SD_TRX_FREQUENCY,
+                  bool crc_on = MBED_CONF_SD_CRC_ENABLED);
+
+    /** Creates an SDBlockDevice on a SPI bus specified by pins (using static pin-map).
+     * This version creates an SPI object that uses GPIO for its chip select line instead of
+     * a dedicated hardware CS pin.
+     *
+     *  @param spi_pinmap Static SPI pin-map
+     *  @param hz         Clock speed of the SPI bus (defaults to 1MHz)
+     *  @param crc_on     Enable cyclic redundancy check (defaults to disabled)
+     */
+    SDBlockDevice(const spi_pinmap_t &spi_pinmap,
+                  mbed::use_gpio_ssel_t,
                   PinName cs = MBED_CONF_SD_SPI_CS,
                   uint64_t hz = MBED_CONF_SD_TRX_FREQUENCY,
                   bool crc_on = MBED_CONF_SD_CRC_ENABLED);
diff --git a/storage/blockdevice/COMPONENT_SD/source/SDBlockDevice.cpp b/storage/blockdevice/COMPONENT_SD/source/SDBlockDevice.cpp
index ad90a4e..46ba15a 100644
--- a/storage/blockdevice/COMPONENT_SD/source/SDBlockDevice.cpp
+++ b/storage/blockdevice/COMPONENT_SD/source/SDBlockDevice.cpp
@@ -251,16 +251,19 @@
 // Only HC block size is supported. Making this a static constant reduces code size.
 const uint32_t SDBlockDevice::_block_size = BLOCK_SIZE_HC;
 
-#if MBED_CONF_SD_CRC_ENABLED
 SDBlockDevice::SDBlockDevice(PinName mosi, PinName miso, PinName sclk, PinName cs, uint64_t hz, bool crc_on)
-    : _sectors(0), _spi(mosi, miso, sclk, cs, use_gpio_ssel), _is_initialized(0),
+    : _sectors(0), _spi(mosi, miso, sclk, cs), _is_initialized(0),
+#if MBED_CONF_SD_CRC_ENABLED
       _init_ref_count(0), _crc_on(crc_on)
 #else
-SDBlockDevice::SDBlockDevice(PinName mosi, PinName miso, PinName sclk, PinName cs, uint64_t hz, bool crc_on)
-    : _sectors(0), _spi(mosi, miso, sclk, cs, use_gpio_ssel), _is_initialized(0),
       _init_ref_count(0)
 #endif
 {
+#if !MBED_CONF_SD_CRC_ENABLED
+    // If this assert fails, this code was compiled without CRC support but you tried to use it.
+    MBED_ASSERT(!crc_on);
+#endif
+
     _card_type = SDCARD_NONE;
 
     // Set default to 100kHz for initialisation and 1MHz for data transfer
@@ -272,16 +275,67 @@
     _erase_size = BLOCK_SIZE_HC;
 }
 
+SDBlockDevice::SDBlockDevice(mbed::use_gpio_ssel_t, PinName mosi, PinName miso, PinName sclk, PinName cs, uint64_t hz, bool crc_on)
+    : _sectors(0), _spi(mosi, miso, sclk, cs, use_gpio_ssel), _is_initialized(0),
 #if MBED_CONF_SD_CRC_ENABLED
-SDBlockDevice::SDBlockDevice(const spi_pinmap_t &spi_pinmap, PinName cs, uint64_t hz, bool crc_on)
-    : _sectors(0), _spi(spi_pinmap, cs), _is_initialized(0),
       _init_ref_count(0), _crc_on(crc_on)
 #else
-SDBlockDevice::SDBlockDevice(const spi_pinmap_t &spi_pinmap, PinName cs, uint64_t hz, bool crc_on)
-    : _sectors(0), _spi(spi_pinmap, cs), _is_initialized(0),
       _init_ref_count(0)
 #endif
 {
+#if !MBED_CONF_SD_CRC_ENABLED
+    // If this assert fails, this code was compiled without CRC support but you tried to use it.
+    MBED_ASSERT(!crc_on);
+#endif
+
+    _card_type = SDCARD_NONE;
+
+    // Set default to 100kHz for initialisation and 1MHz for data transfer
+    static_assert(((MBED_CONF_SD_INIT_FREQUENCY >= 100000) && (MBED_CONF_SD_INIT_FREQUENCY <= 400000)),
+                  "Initialization frequency should be between 100KHz to 400KHz");
+    _init_sck = MBED_CONF_SD_INIT_FREQUENCY;
+    _transfer_sck = hz;
+
+    _erase_size = BLOCK_SIZE_HC;
+}
+
+SDBlockDevice::SDBlockDevice(const spi_pinmap_t &spi_pinmap, uint64_t hz, bool crc_on)
+        : _sectors(0), _spi(spi_pinmap), _is_initialized(0),
+#if MBED_CONF_SD_CRC_ENABLED
+          _init_ref_count(0), _crc_on(crc_on)
+#else
+_init_ref_count(0)
+#endif
+{
+#if !MBED_CONF_SD_CRC_ENABLED
+    // If this assert fails, this code was compiled without CRC support but you tried to use it.
+    MBED_ASSERT(!crc_on);
+#endif
+
+    _card_type = SDCARD_NONE;
+
+    // Set default to 100kHz for initialisation and 1MHz for data transfer
+    static_assert(((MBED_CONF_SD_INIT_FREQUENCY >= 100000) && (MBED_CONF_SD_INIT_FREQUENCY <= 400000)),
+                  "Initialization frequency should be between 100KHz to 400KHz");
+    _init_sck = MBED_CONF_SD_INIT_FREQUENCY;
+    _transfer_sck = hz;
+
+    _erase_size = BLOCK_SIZE_HC;
+}
+
+SDBlockDevice::SDBlockDevice(const spi_pinmap_t &spi_pinmap, mbed::use_gpio_ssel_t, PinName cs, uint64_t hz, bool crc_on)
+    : _sectors(0), _spi(spi_pinmap, cs), _is_initialized(0),
+#if MBED_CONF_SD_CRC_ENABLED
+      _init_ref_count(0), _crc_on(crc_on)
+#else
+      _init_ref_count(0)
+#endif
+{
+#if !MBED_CONF_SD_CRC_ENABLED
+    // If this assert fails, this code was compiled without CRC support but you tried to use it.
+    MBED_ASSERT(!crc_on);
+#endif
+
     _card_type = SDCARD_NONE;
 
     // Set default to 100kHz for initialisation and 1MHz for data transfer