diff --git a/Makefile b/Makefile
index 8ef594a..16df0b5 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ LD:=$(CROSS_COMPILE)gcc
 USECFS:=$(HOME)/src/usecfs
 WOLFSSL:=$(HOME)/src/wolfssl
 
-OBJS:=startup.o main.o system.o  $(USECFS)/src/usecfs_dev_spi.o $(USECFS)/src/usecfs.o mem.o led.o \
+OBJS:=startup.o main.o system.o  usecfs_dev_spi.o $(USECFS)/src/usecfs.o mem.o led.o \
 	i2c.o display.o font_twisted.o spi.o spi_flash.o button.o systick.o newlib.o uart.o ui.o \
 	sdcard.o random.o
 OBJS+= \
@@ -30,7 +30,7 @@ LSCRIPT:=target.ld
 
 OBJCOPY:=$(CROSS_COMPILE)objcopy
 
-CFLAGS:=-mcpu=cortex-m3 -mthumb -Wall -Wno-main -Wstack-usage=200 -ffreestanding -Wno-unused -DBLOCK_SIZE=512 -I$(USECFS)/src -I. -I$(WOLFSSL) -Ilib/unicore-mx/include
+CFLAGS:=-mcpu=cortex-m3 -mthumb -Wall -Wno-main -Wstack-usage=200 -ffreestanding -Wno-unused -DBLOCK_SIZE=4096 -I$(USECFS)/src -I. -I$(WOLFSSL) -Ilib/unicore-mx/include
 CFLAGS+=-specs=nano.specs -lc -lg 
 CFLAGS+=$(UMXFLAGS)
 #CFLAGS+=-O2
diff --git a/button.c b/button.c
index 8830131..c1b030a 100644
--- a/button.c
+++ b/button.c
@@ -19,6 +19,16 @@
 #include "unicore-mx/stm32/f4/adc.h"
 #include "unicore-mx/stm32/f4/nvic.h"
 
+// Uncomment to enable debug
+//#define BUTTON_DEBUG
+
+
+#ifdef BUTTON_DEBUG
+#   define DBG printf
+#else
+#   define DBG(...) do {} while (0)
+#endif
+
 #define BUTTON_DEBOUNCE_TIME 50
 #define BUTTON_HOLD_TIME 1500
 
@@ -142,7 +152,7 @@ int button_poll(void (*callback)(uint8_t press, int hold))
             if((Buttons[b].state == IDLE) || (Buttons[b].state == RELEASING)) {
                 Buttons[b].state = PRESSING;
                 Buttons[b].transition_start_timestamp = jiffies;
-                printf("%06u: ST: PRESSING\r\n", jiffies);
+                DBG("%06u: ST: PRESSING\r\n", jiffies);
                 button_press_pending = 0;
                 return 0;
             } else {
@@ -153,13 +163,13 @@ int button_poll(void (*callback)(uint8_t press, int hold))
                         Buttons[b].state = HOLD;
                         Buttons[b].transition_start_timestamp = jiffies;
                         button_press_pending = 0;
-                        printf("%06u: ST: HOLD\r\n", jiffies);
+                        DBG("%06u: ST: HOLD\r\n", jiffies);
                     }
                 } else if (p_interval > BUTTON_DEBOUNCE_TIME) {
                     if (Buttons[b].state == PRESSING) {
                         callback(b, 0);
                         Buttons[b].state = PRESSED;
-                        printf("%06u: ST: PRESSED\r\n", jiffies);
+                        DBG("%06u: ST: PRESSED\r\n", jiffies);
                         button_press_pending = 0;
                     }
                     if (Buttons[b].state == HOLD) {
@@ -178,12 +188,12 @@ int button_poll(void (*callback)(uint8_t press, int hold))
                     if ((jiffies - Buttons[i].transition_start_timestamp) > (BUTTON_DEBOUNCE_TIME)) {
                         Buttons[i].state = IDLE;
                         Buttons[i].transition_start_timestamp = 0;
-                        printf("%06u: ST: IDLE\r\n", jiffies);
+                        DBG("%06u: ST: IDLE\r\n", jiffies);
                     }
                 } else if (Buttons[i].state != IDLE) {
                     Buttons[i].state = RELEASING;
                     Buttons[i].transition_start_timestamp = jiffies;
-                    printf("%06u: ST:0\r\n", jiffies);
+                    DBG("%06u: ST:0\r\n", jiffies);
                 }
             }
         }
diff --git a/sdcard.c b/sdcard.c
index 0e4e354..2a204b7 100644
--- a/sdcard.c
+++ b/sdcard.c
@@ -31,9 +31,7 @@
 #include "system.h"
 #include "sdcard.h"
 
-#if (!defined(BLOCK_SIZE)) || (BLOCK_SIZE != 512)
-#   error BLOCK_SIZE undefined or invalid
-#endif
+#define SDCARD_BLOCK_SIZE 512
 
 #ifndef NULL
 #define NULL (void *)(0x00000000)
@@ -391,7 +389,7 @@ sdio_scr(struct dev_sd *sd, SDIO_CARD c) {
  * Read a Block from our Card
  *
  * NB: There is a possibly useless test in this code, during the read
- * phase it allows that the SDIO card might try to send more than BLOCK_SIZE
+ * phase it allows that the SDIO card might try to send more than SDCARD_BLOCK_SIZE
  * bytes (128 32 bit longs) and allows it to do so, constantly over
  * writing the last long in the just-in-case-over-long-by-1 data buffer.
  * To compromise the system you would need a borked or custom crafted
@@ -410,14 +408,14 @@ int sdcard_read(void *dev, void *_buf, uint32_t lba)
     uint32_t buf_len = 0;
 
     if (! SDIO_CARD_CCS(sd->card)) {
-        addr = lba * BLOCK_SIZE; // non HC cards use byte address
+        addr = lba * SDCARD_BLOCK_SIZE; // non HC cards use byte address
     }
     err = sdio_select(sd, sd->card->rca);
     if (! err) {
-        err = stm32_sdio_command(sd, 16, BLOCK_SIZE);
+        err = stm32_sdio_command(sd, 16, SDCARD_BLOCK_SIZE);
         if (!err) {
             SDIO_DTIMER = 0xffffffff;
-            SDIO_DLEN = BLOCK_SIZE;
+            SDIO_DLEN = SDCARD_BLOCK_SIZE;
             SDIO_DCTRL = SDIO_DCTRL_DBLOCKSIZE_9 |
                          SDIO_DCTRL_DTDIR |
                          SDIO_DCTRL_DTEN;
@@ -442,7 +440,7 @@ int sdcard_read(void *dev, void *_buf, uint32_t lba)
                         err = SDIO_EUNKNOWN; // Unknown Error!
                     }
                 } else {
-                    err = BLOCK_SIZE;
+                    err = SDCARD_BLOCK_SIZE;
                 }
             }
         }
@@ -471,16 +469,16 @@ int sdcard_write(void *dev, void *_buf, uint32_t lba)
 
 
     if (! SDIO_CARD_CCS(c)) {
-        addr = lba * BLOCK_SIZE; // non HC cards use byte address
+        addr = lba * SDCARD_BLOCK_SIZE; // non HC cards use byte address
     }
 
     err = sdio_select(sd, c->rca);
     if (! err) {
-        /* Set Block Size to BLOCK_SIZE */
-        err = stm32_sdio_command(sd, 16, BLOCK_SIZE);
+        /* Set Block Size to SDCARD_BLOCK_SIZE */
+        err = stm32_sdio_command(sd, 16, SDCARD_BLOCK_SIZE);
         if (!err) {
             SDIO_DTIMER = 0xffffffff;
-            SDIO_DLEN = BLOCK_SIZE;
+            SDIO_DLEN = SDCARD_BLOCK_SIZE;
             SDIO_DCTRL = SDIO_DCTRL_DBLOCKSIZE_9 |
                          SDIO_DCTRL_DTEN;
             err = stm32_sdio_command(sd, 24, addr);
@@ -509,7 +507,7 @@ int sdcard_write(void *dev, void *_buf, uint32_t lba)
     // deselect the card
     (void) sdio_select(sd, 0);
     if (err == 0)
-        return BLOCK_SIZE;
+        return SDCARD_BLOCK_SIZE;
     return err;
 }
 
@@ -689,10 +687,10 @@ stm32_sdio_open(struct dev_sd *sd) {
      * In the V1 Case :
      *     Size = 1<<BLOCK_LEN * 1<<(MULT+2) * (C_SIZE+1) bytes.
      * In the V2 Case :
-     *     Size = (C_SIZE + 1) * BLOCK_SIZEK bytes.
-     * But for our structure we want the size in BLOCK_SIZE byte "blocks"
+     *     Size = (C_SIZE + 1) * SDCARD_BLOCK_SIZEK bytes.
+     * But for our structure we want the size in SDCARD_BLOCK_SIZE byte "blocks"
      * since that is the addressing unit we're going to export so
-     * we compute the size / BLOCK_SIZE as the "size" for the structure.
+     * we compute the size / SDCARD_BLOCK_SIZE as the "size" for the structure.
      */
 
     if (! err) {
diff --git a/ui.c b/ui.c
index 944a73d..d47a6f4 100644
--- a/ui.c
+++ b/ui.c
@@ -14,10 +14,15 @@
 #include <string.h>
 #include "usecfs.h"
 
+
+/* Uncomment for device initialization */
+//#define DEVICE_INITIALIZATION
+
 static const char welcome_message0[]= "  There is no  ";
 static const char welcome_message1[]= "knowledge that ";
 static const char welcome_message2[]= " is not power. ";
 
+
 static const uint8_t uuid[UUID_LEN] = {
     0xb4, 0x6b, 0x82, 0x05, 0xb6, 0xcd, 0x28, 0xaa, 0xc7, 0x81, 0x2e, 0x2d,
     0xfd, 0xdd, 0x5e, 0x70, 0x3f, 0xbf, 0x09, 0x03, 0x1b, 0x5f, 0xbe, 0xc6,
@@ -55,15 +60,22 @@ void ui_msg(const char *txt)
 void lock(void)
 {
     //led_on(RED_LED);
-    ui_msg("Locked.");
+    ui_msg("Device is Locked");
     fsm_state = ST_LOCKED;
 }
 
+static void pwrst(void)
+{
+    memset(password, 0, MAX_PASSWORD);
+    pin_idx = 0;
+}
+
 int unlock(void)
 {
     uint8_t stored_uuid[UUID_LEN];
     if (pin_idx < 6) {
-        ui_msg("pin code too short");
+        display_text(6, "Failed.");
+        pwrst();
         return -1;
     }
     display_scroll(NULL, 0);
@@ -72,7 +84,7 @@ int unlock(void)
     display_text(5, "Unlocking secret");
     if ((usecfs_init(password, 0, stored_uuid) == 0) &&
             (memcmp(stored_uuid, uuid, UUID_LEN) == 0)) {
-        memset(password, 0, MAX_PASSWORD);
+        pwrst();
         fsm_state = ST_UNLOCKED;
         ui_msg("Device UNLOCKED");
         return 0;
@@ -85,8 +97,7 @@ int unlock(void)
         }
 #endif
         display_text(6, "Failed.");
-        memset(password, 0, MAX_PASSWORD);
-        pin_idx = 0;
+        pwrst();
         fsm_state = ST_LOCKED;
         return -1;
     }
@@ -134,9 +145,8 @@ void ui_button_press(uint16_t button)
     int i;
     char c;
     if (fsm_state == ST_LOCKED) {
+        pwrst();
         ui_msg("Insert pin:");
-        pin_idx = 0;
-        memset(password, 0, MAX_PASSWORD);
         fsm_state = ST_PIN_ENTRY;
         return;
     }