diff --git a/uart_commands.c b/uart_commands.c
index 43e1248..9a614eb 100644
--- a/uart_commands.c
+++ b/uart_commands.c
@@ -9,6 +9,12 @@ void digit_to_str(char* str, uint32_t number){
 	itoa(number,str,16);
 }
 
+int addr_to_sector(int addr){
+	int tmp = addr & 0xfffff;
+	tmp = tmp >> 12;
+	return tmp;
+}
+
 void uart_commands_getid(error_code* status){
     char hex[15] = "0x26113f37\r\n";
 	//char hex[15];
@@ -31,19 +37,37 @@ void uart_commands_getserial(error_code* status){
     //sprintf(hex, "0x%x%x%x%x\r\n", res[0], res[1], res[2], res[3]);
     if(*status == 0){
         uart_send_ok();
-        uart_send(hex, 35);
+        uart_send(hex, strlen(hex));
     }
 }
 
 crc_t uart_commands_prog(error_code* status, int size){
-	iap_prepare_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+5);
-	iap_erase_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+5);
-	iap_prepare_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+5);
+	//iap_prepare_sectors(status, APP_OFFSET, APP_OFFSET+size/4095+5);
+	iap_prepare_sectors(status, addr_to_sector(APP_OFFSET), addr_to_sector(APP_OFFSET+size)+1);
+	char digit;
+	if(*status != ok){
+		uart_send_err();
+		itoa(*status, &digit, 10);
+		uart_send(digit, 1);
+	}
+	iap_erase_sectors(status, addr_to_sector(APP_OFFSET), addr_to_sector(APP_OFFSET+size)+1);
+	if(*status != ok){
+		uart_send_err();
+		itoa(*status, &digit, 10);
+		uart_send(digit, 1);
+	}
+	iap_prepare_sectors(status, addr_to_sector(APP_OFFSET), addr_to_sector(APP_OFFSET+size)+1);
+	if(*status != ok){
+		uart_send_err();
+		itoa(*status, &digit, 10);
+		uart_send(digit, 1);
+	}
 	uart_send_ok();
 	return crc_init();
 }
 
 error_code uart_commands_data(error_code* status, int size, crc_t* checksum_global, crc_t checksum_loc, int offset){
+	char digit;
 	uart_receive_data(data, size);
 	crc_t checksum_tmp = crc_init();
 	checksum_tmp = crc_update(checksum_tmp, data, size);
@@ -53,7 +77,7 @@ error_code uart_commands_data(error_code* status, int size, crc_t* checksum_glob
 		int tmp = size;
 		//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+5);
+		iap_prepare_sectors(status, addr_to_sector(offset), addr_to_sector(offset+size)+1);
 		*checksum_global = crc_update(*checksum_global, data, size);
 		//verify if size == 4095 if smaller 
 		if(size == 0x0400)
@@ -64,14 +88,18 @@ error_code uart_commands_data(error_code* status, int size, crc_t* checksum_glob
 		}
 		if(*status != ok){
 			uart_send_err();
+			itoa(*status, &digit, 10);
+			uart_send(digit, 1);
 			return *status;
 		}
 		uart_send_ok();
 		return ok;
 	}else{
 		uart_send_err();
-		return local_checksum;
+		itoa(*status, &digit, 10);
+		uart_send(digit, 1);
 	}
+		return local_checksum;
 }
 
 error_code uart_commands_check(crc_t crc_received, crc_t crc_calculated){
diff --git a/uart_commands.h b/uart_commands.h
index 018b238..c52c628 100644
--- a/uart_commands.h
+++ b/uart_commands.h
@@ -7,7 +7,7 @@
 #include "crc.h"
 
 #define  DELIMIERS ","
-#define APP_OFFSET 4
+#define APP_OFFSET 0x4000
 
 
 
@@ -35,6 +35,8 @@ void uart_send_ok();
 
 void uart_send_err();
 
+int addr_to_sector(int addr);
+
 void digit_to_str(char* str, uint32_t number);
 
 uint32_t uart_string_to_int(const char* str);