Merge pull request ARMmbed#91 from deepikabhavnani/conf_init_freq

Config option for initialization frequency

Author: Deepika

SDBlockDevice.cpp

@@ -159,6 +159,11 @@
 #define MBED_CONF_SD_CMD0_IDLE_STATE_RETRIES     5      /*!< Number of retries for sending CMDO */
 #endif
 
+#ifndef MBED_CONF_SD_INIT_FREQUENCY
+#define MBED_CONF_SD_INIT_FREQUENCY              100000 /*!< Initialization frequency Range (100KHz-400KHz) */
+#endif
+
+
 #define SD_COMMAND_TIMEOUT                       MBED_CONF_SD_CMD_TIMEOUT
 #define SD_CMD0_GO_IDLE_STATE_RETRIES            MBED_CONF_SD_CMD0_IDLE_STATE_RETRIES
 #define SD_DBG                                   0      /*!< 1 - Enable debugging */
@@ -251,7 +256,9 @@ SDBlockDevice::SDBlockDevice(PinName mosi, PinName miso, PinName sclk, PinName c
     _card_type = SDCARD_NONE;
 
     // Set default to 100kHz for initialisation and 1MHz for data transfer
-    _init_sck = 100000;
+    MBED_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;
 
     // Only HC block size is supported.

config/mbed_lib.json

@@ -8,7 +8,8 @@
         "DEVICE_SPI": 1,
         "FSFAT_SDCARD_INSTALLED": 1,
         "CMD_TIMEOUT": 5000,
-        "CMD0_IDLE_STATE_RETRIES" : 5
+        "CMD0_IDLE_STATE_RETRIES": 5,
+        "SD_INIT_FREQUENCY": 100000
     },
     "target_overrides": {
         "DISCO_F051R8": {