diff --git a/bootloader.c b/bootloader.c
index 71cd22f..8265a4c 100644
--- a/bootloader.c
+++ b/bootloader.c
@@ -39,6 +39,7 @@ crc_t crc_prog, crc_data;
 // TODO: insert other definitions and declarations here
 
 char buff[256];
+
 int main(void) {
     uart_init(115200);
     while(1){
@@ -60,7 +61,8 @@ int main(void) {
 		}else if(strcmp("DATA", cmd.argv[0])==0){
 			int size = uart_string_to_int(cmd.argv[1]);
 			crc_t local_checksum = uart_string_to_int(cmd.argv[2]);
-			uart_commands_data(&status, size, &crc_data, local_checksum, offset_pointer);
+			//uart_commands_data(&status, size, &crc_data, local_checksum, offset_pointer);
+			uart_commands_data(&status, size, &crc_data, crc_data, offset_pointer);
 			if(status == 0) offset_pointer += size;
 
 		}else if(strcmp("CHECK", cmd.argv[0])==0){
diff --git a/iap.c b/iap.c
index 2b2e22f..7bc2a32 100644
--- a/iap.c
+++ b/iap.c
@@ -92,8 +92,9 @@ uint32_t iap_read_part_id(error_code* status){
 }
 
 void iap_copy_to_flash(error_code* status, int dst_flash, uint32_t* src_ram, int num_bytes){
-    iap_prepare_sectors(status, dst_flash, dst_flash+num_bytes);
-	//iap_prepare_sectors(2, 9);
+    //iap_prepare_sectors(status, dst_flash, dst_flash+num_bytes);
+    //iap_erase_sectors(status, dst_flash, dst_flash+num_bytes);
+    //iap_prepare_sectors(status, dst_flash, dst_flash+num_bytes);
     command[0] = 51;
     command[1] = dst_flash;
     command[2] = *src_ram;
diff --git a/uart.c b/uart.c
index 5559b9c..a557570 100644
--- a/uart.c
+++ b/uart.c
@@ -45,21 +45,27 @@ void uart_send(char* buff, uint32_t length){
 
 void uart_receive_command(char* chara){
 	char* curr = chara;
+    while(((LPC_UART0->LSR)&(1)) == 0);
+    *curr = LPC_UART0->RBR;
     //while(strncmp("\r\n",curr, 2) != 0){
 	while(*curr != '\n'){
+        if((*curr != '\n')) curr++;
         while(((LPC_UART0->LSR)&(1)) == 0);
         *curr = LPC_UART0->RBR;
         //if(strncmp("\r\n",curr, 2) != 0) curr++;
-        if((*curr != '\n')) curr++;
     }
 }
 
-void uart_receive_data(uint8_t* chara){
+void uart_receive_data(uint8_t* chara, int size){
 	//size parameter add while size != size_given
 	uint8_t* curr = chara;
-    while(*curr != '\0'){
-        while(((LPC_UART0->LSR)&(1)) == 0);
-        *curr = LPC_UART0->RBR;
-        curr++;
+    //while(((LPC_UART0->LSR)&(1)) == 0);
+    for(int i = 0; i < size/2; i++){
+    	while(((LPC_UART0->LSR)&(1)) == 0);
+    	curr[2*i] = LPC_UART0->RBR;
+    	while(((LPC_UART0->LSR)&(1)) == 0);
+        curr[2*i+1] = LPC_UART0->RBR;
+        //while(((LPC_UART0->LSR)&(1)) == 0);
+        //curr[2*i] = LPC_UART0->RBR;
     }
 }
diff --git a/uart.h b/uart.h
index c54416f..170ea80 100644
--- a/uart.h
+++ b/uart.h
@@ -44,7 +44,7 @@ void uart_send(char* buff, uint32_t length);
 
 void uart_receive_command(char* chara);
 
-void uart_receive_data(uint8_t* chara);
+void uart_receive_data(uint8_t* chara, int size);
 
 
 #define THRE        (1<<5)
diff --git a/uart_commands.c b/uart_commands.c
index acce2bb..e32740e 100644
--- a/uart_commands.c
+++ b/uart_commands.c
@@ -28,39 +28,43 @@ void uart_commands_getserial(error_code* status){
 }
 
 crc_t uart_commands_prog(void){
-	return crc_init();
 	uart_send(OK, 5);
+	return crc_init();
 }
 
 error_code uart_commands_data(error_code* status, int size, crc_t* checksum_global, crc_t checksum_loc, int offset){
-	uart_receive_data(data);
+	uart_receive_data(data, size);
 	crc_t checksum_tmp = crc_init();
 	checksum_tmp = crc_update(checksum_tmp, data, size);
+	checksum_tmp = crc_finalize(checksum_tmp);
 	if(checksum_loc == checksum_tmp){
 		int tmp = size;
-		while(tmp > 4096){
-			iap_copy_to_flash(status, offset, &checksum_loc, 4096);
+		iap_prepare_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+1);
+		iap_erase_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+1);
+		iap_prepare_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+1);
+		while(tmp >= 4096){
+			iap_copy_to_flash(status, offset/0x1000, &checksum_loc, 4096);
 			if(*status != ok){
 				uart_send(ERR, 6);
 			}
 			tmp = tmp - 4096;
 		}
-		while(tmp > 1024){
-			iap_copy_to_flash(status, offset, &checksum_loc, 1024);
+		while(tmp >= 1024){
+			iap_copy_to_flash(status, offset/0x1000, &checksum_loc, 1024);
 			if(*status != ok){
 				uart_send(ERR, 6);
 			}
 			tmp = tmp - 1024;
 		}
-		while(tmp > 512){
-			iap_copy_to_flash(status, offset, &checksum_loc, 512);
+		while(tmp >= 512){
+			iap_copy_to_flash(status, offset/0x1000, &checksum_loc, 512);
 			if(*status != ok){
 				uart_send(ERR, 6);
 			}
 			tmp = tmp - 512;
 		}
-		while(tmp > 256){
-			iap_copy_to_flash(status, offset, &checksum_loc, 256);
+		while(tmp >= 256){
+			iap_copy_to_flash(status, offset/0x1000, &checksum_loc, 256);
 			if(*status != ok){
 				uart_send(ERR, 6);
 			}
@@ -108,6 +112,6 @@ int uart_parse_command(char *user_input, cmd_t *cmd) {
 uint32_t uart_string_to_int(const char *str) {
     // Convert input in port number
 	char* tmp;
-    unsigned long int hex = strtoul(str, tmp, 16);
+    unsigned long long int hex = strtoull(str, &tmp, 16);
     return hex;
 }
diff --git a/uart_commands.h b/uart_commands.h
index 29f959c..6cead02 100644
--- a/uart_commands.h
+++ b/uart_commands.h
@@ -6,7 +6,8 @@
 #include "iap.h"
 #include "crc.h"
 
-#define  DELIMIERS ','
+#define  DELIMIERS ","
+#define APP_OFFSET 4