diff --git a/bootloader.c b/bootloader.c
index fa5662a..2a63285 100644
--- a/bootloader.c
+++ b/bootloader.c
@@ -31,7 +31,7 @@ char* argvs[3][10];
 
 cmd_t cmd;
 
-uint32_t* size_store = (uint32_t*) 0x3400;
+uint32_t* size_store = (uint32_t*) 0x3100;
 crc_t* crc_store = (crc_t*) 0x3000;
 
 uint32_t offset, total_size, offset_pointer;
@@ -49,6 +49,7 @@ int is_code_valid(){
 	crc_t expected_crc = *crc_store;
 	size_t application_size = *size_store;
 	crc_t real_crc = crc_init();
+	if(application_size > MAX_PROG_SIZE) return 0;
 	real_crc = crc_update(real_crc, (void*)APP_OFFSET, application_size);
 	real_crc = crc_finalize(real_crc);
 	error_code is_error = uart_commands_check(real_crc, expected_crc);
@@ -58,6 +59,13 @@ int is_code_valid(){
 	else return 0;
 }
 
+int is_b_pressed(){
+	int tmp = (LPC_GPIO0->FIOPIN)>>19;
+	int tmp2 = tmp & 1;
+	if(tmp2 == 0) return 1;
+	else return 0;
+}
+
 void write_app_info(crc_t* checksum, size_t* size){
 	iap_prepare_sectors(&status, addr_to_sector(0x3000), addr_to_sector(0x3fff));
 	if(status != ok){
@@ -67,60 +75,72 @@ void write_app_info(crc_t* checksum, size_t* size){
 	if(status != ok){
 		uart_send_err();
 	}
-	iap_prepare_sectors(&status, addr_to_sector(0x3000), addr_to_sector(0x3fff));
-	if(status != ok){
-		uart_send_err();
+	iap_copy_to_flash(&status, (long unsigned int *)crc_store, (long unsigned int*)checksum, 0x100);
+	//0x100 a result of trial and error I initially wanted to put 0x4 but noooo it doesn't work
+	iap_copy_to_flash(&status, (long unsigned int *)size_store, (long unsigned int*)size, 0x100);
+}
+
+void launch_program(){
+	SCB->VTOR = APP_OFFSET;
+	__asm("ldr r0,=0x4000");
+	__asm("ldr sp,[r0]");
+	__asm("ldr pc,[r0,#4]");
+}
+
+void manage_bootloader(){
+	cmd.argv = (char**)argvs;
+	while(1){
+		uart_receive_command(buff);
+		uart_parse_command(buff, &cmd);
+		if (strncmp("GETID", cmd.argv[0], 5)==0){
+			uart_commands_getid(&status);
+
+		}else if(strncmp("GETSE", cmd.argv[0], 5)==0){
+			uart_commands_getserial(&status);
+
+		}else if(strncmp("PROG", cmd.argv[0], 4)==0){
+			crc_prog = uart_string_to_int(cmd.argv[3]);
+			total_size = uart_string_to_int(cmd.argv[2]);
+			offset = uart_string_to_int(cmd.argv[1]);
+			write_app_info(&crc_prog, (unsigned int *)&total_size);
+			crc_data = uart_commands_prog(&status, total_size);
+			offset_pointer = offset;
+
+		}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);
+			if(status == 0) offset_pointer += size;
+
+		}else if(strncmp("CHECK", cmd.argv[0], 5)==0){
+			error_code is_error = uart_commands_check(crc_prog, crc_data);
+			if(is_error == ok){
+				uart_send_ok();
+				break;
+			}else{
+				uart_send_err();
+			}
+
+		}
 	}
-	iap_copy_to_flash(&status, (long unsigned int *)crc_store, (long unsigned int*)checksum, 0x0400);
-	iap_copy_to_flash(&status, (long unsigned int *)size_store, (long unsigned int*)size, 0x0400);
 }
 
 int main(void) {
-	cmd.argv = (char**)argvs;
 	//verify b is pressed
 	//checksum is correct (
 	//bootloader_init();
     uart_init(115200);
-	if(is_code_valid()){
-		SCB->VTOR = APP_OFFSET;
-		__asm("ldr r0,=0x4000");
-		__asm("ldr sp,[r0]");
-		__asm("ldr pc,[r0,#4]");
-	}else{
-		while(1){
-			uart_receive_command(buff);
-			uart_parse_command(buff, &cmd);
-			if (strncmp("GETID", cmd.argv[0], 5)==0){
-				uart_commands_getid(&status);
-
-			}else if(strncmp("GETSE", cmd.argv[0], 5)==0){
-				uart_commands_getserial(&status);
-
-			}else if(strncmp("PROG", cmd.argv[0], 4)==0){
-				crc_prog = uart_string_to_int(cmd.argv[3]);
-				total_size = uart_string_to_int(cmd.argv[2]);
-				offset = uart_string_to_int(cmd.argv[1]);
-				write_app_info(&crc_prog, (unsigned int *)&total_size);
-				crc_data = uart_commands_prog(&status, total_size);
-				offset_pointer = offset;
-
-			}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);
-				if(status == 0) offset_pointer += size;
-
-			}else if(strncmp("CHECK", cmd.argv[0], 5)==0){
-				error_code is_error = uart_commands_check(crc_prog, crc_data);
-				if(is_error == ok){
-					uart_send_ok();
-				}else{
-					uart_send_err();
-				}
-
-			}
+    LPC_GPIO0->FIODIR &=~(1<<19);
+    if(is_b_pressed() == 0){
+		if(is_code_valid()){
+			launch_program();
+		}else{
+			manage_bootloader();
 		}
+	}else{
+		manage_bootloader();
 	}
+	launch_program();
     while(1);
     return 0 ;
 }
diff --git a/uart_commands.h b/uart_commands.h
index 3df8f1a..c6146fc 100644
--- a/uart_commands.h
+++ b/uart_commands.h
@@ -7,7 +7,9 @@
 #include "crc.h"
 
 #define  DELIMIERS ","
+#define LPC1769_FLASH_SIZE 0x80000
 #define APP_OFFSET 0x4000
+#define MAX_PROG_SIZE (LPC1769_FLASH_SIZE - APP_OFFSET)