diff --git a/app/app.c b/app/app.c
index 97034e4..cf80452 100644
--- a/app/app.c
+++ b/app/app.c
@@ -5,11 +5,9 @@ void app() {
     init_LWIP();
 
     while(1) {
-        // process_LWIP();
-        uint32_t regvalue = 0;
-        HAL_ETH_ReadPHYRegister(getEthStruct(), 1, &regvalue);
-        delay(500);
-        printf("Test: %d\r\n", regvalue);
+        process_LWIP();
+        // GPIO_ToggleBits(GPIOB, GPIO_Pin_7);
+        delay(400);
     };
 }
 
diff --git a/bsp/CMakeLists.txt b/bsp/CMakeLists.txt
index 8aeefbe..955c325 100644
--- a/bsp/CMakeLists.txt
+++ b/bsp/CMakeLists.txt
@@ -2,11 +2,6 @@ set(LWIP_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/lwip/src)
 set(LWIP_INCLUDES ${CMAKE_CURRENT_SOURCE_DIR}/lwip/src/include)
 set(LWIP_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/lwip/src/core)
 
-file(GLOB_RECURSE LWIP_SOURCES 
-    ${LWIP_SOURCE_DIR}/core/*.c
-    ${LWIP_SOURCE_DIR}/netif/*.c
-)
-
 add_library(bsp STATIC    
     bsp.c
     lwip/lwip.c
diff --git a/bsp/bsp.c b/bsp/bsp.c
index 1bb2a81..0071aa2 100644
--- a/bsp/bsp.c
+++ b/bsp/bsp.c
@@ -1,6 +1,3 @@
-#include "stm32f4xx_gpio.h"
-#include "stm32f4xx_rcc.h"
-#include "stm32f4xx_dma.h"
 #include "misc.h"
 #include "bsp.h"
 #include "lwip.h"
@@ -15,6 +12,12 @@ static volatile uint32_t cnt = 0;
 void SysTick_Handler(void)
 {
     if (cnt == INTERVAL) {
+
+        // uint32_t regvalue = 0;
+        // HAL_ETH_ReadPHYRegister(getEthStruct(), 1, &regvalue);
+
+        // printf("PHY: %d\r\n", regvalue);
+
         GPIO_ToggleBits(GPIOB, GPIO_Pin_14);
         cnt = 0;
     }
@@ -52,7 +55,6 @@ void gpio_init() {
         RCC_AHB1Periph_GPIOG, 
         ENABLE
     );
-
     GPIO_InitTypeDef gpio;
 
     GPIO_StructInit(&gpio);
@@ -60,7 +62,6 @@ void gpio_init() {
     gpio.GPIO_Pin = led_pins;
     GPIO_Init(GPIOB, &gpio);
     GPIO_ResetBits(GPIOB, led_pins);
-
 }
 
 void usart_init() {
@@ -106,6 +107,11 @@ void dma_init() {
 
 
 void eth_init() {
+
+    RCC_AHB1PeriphClockCmd(RCC_AHB1ENR_ETHMACEN, ENABLE);
+    RCC_AHB1PeriphClockCmd(RCC_AHB1ENR_ETHMACRXEN, ENABLE);
+    RCC_AHB1PeriphClockCmd(RCC_AHB1ENR_ETHMACTXEN, ENABLE);
+
     GPIO_InitTypeDef gpio;
 
     gpio.GPIO_Mode = GPIO_Mode_AF;
@@ -134,25 +140,21 @@ void eth_init() {
     GPIO_Init(GPIOB, &gpio);
     GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_ETH); //RMII TXD1
 
-    RCC_AHB1PeriphClockCmd(RCC_AHB1ENR_ETHMACEN, ENABLE);
-    RCC_AHB1PeriphClockCmd(RCC_AHB1ENR_ETHMACRXEN, ENABLE);
-    RCC_AHB1PeriphClockCmd(RCC_AHB1ENR_ETHMACTXEN, ENABLE);
     NVIC_SetPriority(ETH_IRQn, 0);
     NVIC_EnableIRQ(ETH_IRQn);
 }
 
 
 void board_init() {
-    uint32_t tick = SystemCoreClock/1000;
+    uint32_t tick = SystemCoreClock/1000 - 1;
     SysTick_Config(tick);
     NVIC_EnableIRQ(SysTick_IRQn);
-    __enable_irq(); 
+    // __enable_irq(); 
     gpio_init();
     usart_init();
     // dma_init();
     eth_init();
     init_LWIP();
-    delay(50); //wait until periph init
     printf("Controller is started...\r\n");
 }
 
diff --git a/bsp/bsp.h b/bsp/bsp.h
index 5f7d9b9..639e1d5 100644
--- a/bsp/bsp.h
+++ b/bsp/bsp.h
@@ -3,7 +3,9 @@
 
 #include "stm32f4xx.h"
 #include "stm32f4xx_usart.h"
-
+#include "stm32f4xx_gpio.h"
+#include "stm32f4xx_rcc.h"
+#include "stm32f4xx_dma.h"
 void board_init();
 uint32_t getRegister();
 uint32_t getSysTick();
diff --git a/bsp/lwip/ethernetif.c b/bsp/lwip/ethernetif.c
index 8533440..4c62ec1 100644
--- a/bsp/lwip/ethernetif.c
+++ b/bsp/lwip/ethernetif.c
@@ -290,7 +290,6 @@ static struct pbuf * low_level_input(struct netif *netif)
   /* get received frame */
   if (HAL_ETH_GetReceivedFrame(&heth) != HAL_OK)
     return NULL;
-  
   /* Obtain the size of the packet and put it into the "len" variable. */
   len = heth.RxFrameInfos.length;
   buffer = (uint8_t *)heth.RxFrameInfos.buffer;
@@ -354,6 +353,30 @@ static struct pbuf * low_level_input(struct netif *netif)
   return p;
 }
 
+void check_link_status(struct netif* netif) {
+  uint32_t regvalue = 0;
+  if (HAL_ETH_ReadPHYRegister(&heth, PHY_BSR, &regvalue) == HAL_OK)
+  {
+    if((regvalue & PHY_LINKED_STATUS)== (uint16_t)RESET) 
+    {
+        // Link status = disconnected
+        if (netif_is_link_up(netif))
+        {
+            netif_set_down(netif);
+            printf("unplugged\r\n");
+            netif_set_link_down(netif);
+        }
+    } else {
+        // Link status = connected
+        if (!netif_is_link_up(netif))
+        {
+            printf("plugged\r\n");
+            NVIC_SystemReset();
+        }
+    }
+  }
+}
+
 /**
  * This function should be called when a packet is ready to be read
  * from the interface. It uses the function low_level_input() that
@@ -365,24 +388,25 @@ static struct pbuf * low_level_input(struct netif *netif)
  */
 void ethernetif_input(struct netif *netif)
 {
-  err_t err;
-  struct pbuf *p;
-
-  /* move received packet into a new pbuf */
-  p = low_level_input(netif);
+  // err_t err;
+  // struct pbuf *p;
+  // uint32_t regvalue = 0;
+  // /* move received packet into a new pbuf */
+  // p = low_level_input(netif);
+  netif_set_link_callback(netif, ethernetif_update_config);
+  check_link_status(netif);
+  // /* no packet could be read, silently ignore this */
+  // if (p == NULL) return;
     
-  /* no packet could be read, silently ignore this */
-  if (p == NULL) return;
-    
-  /* entry point to the LwIP stack */
-  err = netif->input(p, netif);
-    
-  if (err != ERR_OK)
-  {
-    LWIP_DEBUGF(NETIF_DEBUG, ("ethernetif_input: IP input error\n"));
-    pbuf_free(p);
-    p = NULL;    
-  }
+  // // /* entry point to the LwIP stack */
+  // err = netif->input(p, netif);
+  
+  // if (err != ERR_OK)
+  // {
+  //   LWIP_DEBUGF(NETIF_DEBUG, ("ethernetif_input: IP input error\n"));
+  //   pbuf_free(p);
+  //   p = NULL;    
+  // }
 }
 
 #if !LWIP_ARP
@@ -486,9 +510,10 @@ void ethernetif_update_config(struct netif *netif)
 {
   __IO uint32_t tickstart = 0;
   uint32_t regvalue = 0;
-  
   if(netif_is_link_up(netif))
   { 
+    GPIO_SetBits(GPIOB, GPIO_Pin_0);
+    GPIO_SetBits(GPIOB, GPIO_Pin_7);
     /* Restart the auto-negotiation */
     if(heth.Init.AutoNegotiation != ETH_AUTONEGOTIATION_DISABLE)
     {
@@ -558,7 +583,9 @@ void ethernetif_update_config(struct netif *netif)
   else
   {
     /* Stop MAC interface */
-    HAL_ETH_Stop(&heth);
+    GPIO_ResetBits(GPIOB, GPIO_Pin_0);
+    GPIO_SetBits(GPIOB, GPIO_Pin_7);
+    // HAL_ETH_Stop(&heth);
   }
 
   ethernetif_notify_conn_changed(netif);
diff --git a/bsp/lwip/ethernetif.h b/bsp/lwip/ethernetif.h
index 0350e2f..46d35c4 100644
--- a/bsp/lwip/ethernetif.h
+++ b/bsp/lwip/ethernetif.h
@@ -10,7 +10,7 @@ err_t ethernetif_init(struct netif *netif);
 void ethernetif_input(struct netif *netif);
 void ethernetif_update_config(struct netif *netif);
 void ethernetif_notify_conn_changed(struct netif *netif);
-
+void check_link_status(struct netif* netif);
 u32_t sys_jiffies(void);
 u32_t sys_now(void);
 ETH_HandleTypeDef* getEthStruct();
diff --git a/bsp/lwip/lwip.c b/bsp/lwip/lwip.c
index 57205ac..dec7c5c 100644
--- a/bsp/lwip/lwip.c
+++ b/bsp/lwip/lwip.c
@@ -65,6 +65,6 @@ void init_LWIP(void)
 void process_LWIP()
 {
   ethernetif_input(&gnetif);
-  sys_check_timeouts();
+  // sys_check_timeouts();
 }
 
diff --git a/bsp/lwip/lwipopts.h b/bsp/lwip/lwipopts.h
index 7145b5e..7c2bdd8 100644
--- a/bsp/lwip/lwipopts.h
+++ b/bsp/lwip/lwipopts.h
@@ -76,7 +76,7 @@
 /* LwIP Stack Parameters (modified compared to initialization value in opt.h) -*/
 /* Parameters set in STM32CubeMX LwIP Configuration GUI -*/
 /*----- Value in opt.h for LWIP_DHCP: 0 -----*/
-#define LWIP_DHCP 1
+#define LWIP_DHCP 0
 /*----- Value in opt.h for NO_SYS: 0 -----*/
 #define NO_SYS 1
 /*----- Value in opt.h for SYS_LIGHTWEIGHT_PROT: 1 -----*/
@@ -128,19 +128,19 @@
 /*----- Value in opt.h for CHECKSUM_CHECK_ICMP6: 1 -----*/
 #define CHECKSUM_CHECK_ICMP6 0
 /*----- Default Value for ETHARP_DEBUG: LWIP_DBG_OFF ---*/
-#define ETHARP_DEBUG LWIP_DBG_ON
+#define ETHARP_DEBUG LWIP_DBG_OFF
 /*----- Default Value for NETIF_DEBUG: LWIP_DBG_OFF ---*/
-#define NETIF_DEBUG LWIP_DBG_ON
+#define NETIF_DEBUG LWIP_DBG_OFF
 /*----- Default Value for PBUF_DEBUG: LWIP_DBG_OFF ---*/
 #define PBUF_DEBUG LWIP_DBG_OFF
 /*----- Default Value for ICMP_DEBUG: LWIP_DBG_OFF ---*/
-#define ICMP_DEBUG LWIP_DBG_ON
+#define ICMP_DEBUG LWIP_DBG_OFF
 /*----- Default Value for SYS_DEBUG: LWIP_DBG_OFF ---*/
-#define SYS_DEBUG LWIP_DBG_ON
+#define SYS_DEBUG LWIP_DBG_OFF
 /*----- Default Value for UDP_DEBUG: LWIP_DBG_OFF ---*/
-#define UDP_DEBUG LWIP_DBG_ON
+#define UDP_DEBUG LWIP_DBG_OFF
 /*----- Default Value for DHCP_DEBUG: LWIP_DBG_OFF ---*/
-#define DHCP_DEBUG LWIP_DBG_ON
+#define DHCP_DEBUG LWIP_DBG_OFF
 /*-----------------------------------------------------------------------------*/
 /* USER CODE BEGIN 1 */
 #define LWIP_DEBUG 1
@@ -148,6 +148,8 @@
 #define LWIP_UDP 1
 
 #define LWIP_TCP 0
+
+#define LWIP_NETIF_LINK_CALLBACK 1
 /* USER CODE END 1 */
 
 #ifdef __cplusplus
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 32dc66c..3e536fd 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -1,7 +1,8 @@
 project(stm32f4_lib C ASM)
 
 set(DEVICE_FAMILY STM32F439xx)
-get_filename_component(LINKER_SCRIPT src/stm32f439zi_flash.ld ABSOLUTE)
+# get_filename_component(LINKER_SCRIPT src/stm32f439zi_flash.ld ABSOLUTE)
+get_filename_component(LINKER_SCRIPT src/STM32F439ZITx_FLASH.ld ABSOLUTE)
 
 add_library(stm32f4xx STATIC   
     src/STM32F4xx_StdPeriph_Driver/misc.c
@@ -38,7 +39,8 @@ add_library(stm32f4xx STATIC
     src/STM32F4xx_StdPeriph_Driver/stm32f4xx_usart.c
     # src/STM32F4xx_StdPeriph_Driver/stm32f4xx_wwdg.c  
     src/system_stm32f4xx.c
-    src/startup_stm32f4xx.S
+    # src/startup_stm32f4xx.S
+    src/startup_stm32f439xx.S
 )
 
 target_include_directories(stm32f4xx PUBLIC 
@@ -50,6 +52,7 @@ target_include_directories(stm32f4xx PUBLIC
 target_compile_definitions(stm32f4xx PUBLIC USE_STDPERIPH_DRIVER)
 target_compile_definitions(stm32f4xx PUBLIC ${DEVICE_FAMILY})
 target_compile_definitions(stm32f4xx PUBLIC HSE_VALUE=8000000)
+target_compile_definitions(stm32f4xx PUBLIC SYSTEM_CORE_CLOCK=180000000)
 target_compile_definitions(stm32f4xx PUBLIC USE_STM324x7I_EVAL)
 
 target_compile_options(stm32f4xx PRIVATE -nostartfiles)