LwIP not entering callback when ethernet cable (dis)connected

[NicRoberts]

NUCLEO-F767ZI

I'm trying to use the LwIP middleware which I have enabled in MX.

First I'm trying to check if an ethernet cable is attached or not. I have setup UART3 to use printf (which works as expected)

I've set the callback in lwip.c to print when the cable is removed or plugged in or so I thought but I get no message when I connect or disconnect the cable. The LEDs on the socket light up when the cable is connected, so the board at some level does see the cable. What am I missing here?

EDIT:: LWIP_NETIF_LINK_CALLBACK was enabled in MX

// In main.c
MX_LWIP_Init();

/* USER CODE BEGIN WHILE */
while (1)
{
  MX_LWIP_Process();
  /* USER CODE END WHILE */

  /* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */



// In lwip.c the callback function that is registered in MX_LWIP_Init()
static void ethernet_link_status_updated(struct netif *netif)
{
  if (netif_is_up(netif))
  {
/* USER CODE BEGIN 5 */
	  printf("Cable connected\r\n");
/* USER CODE END 5 */
  }
  else /* netif is down */
  {
/* USER CODE BEGIN 6 */
	  printf("Cable NOT connected\r\n");
/* USER CODE END 6 */
  }
}

[mbarg.1]

You do not have a connection manager - demo does not (most cases) it - there are many other cases, choices, features requiring sw management that are not handled in demo.

I usually suggest to draw a set of requirements you want in your system and compare with actual demo code to get double sure that minimum system is hat your customers can accept.

[NicRoberts]

My only requirement at the moment is to check if the cable is connected.

[STackPointer64]

Hello @NicRoberts,

Have you tried setting a breakpoint on the `if` condition to check whether it is triggered?

Best regards,

[NicRoberts]

Going through the debug it doesn't get anywhere near, doesn't get past the memory initialisation, 

MX_LWIP_Init()

____lwip_init()

________mem_init()

__________mem->prev = 0;

HardFault_Handler()

[STackPointer64 · Accepted solution]

Have you configured the Ethernet DMA descriptors, LwIP, and the MPU correctly? If you attach your project, I can analyze it and look for misconfigurations. I also suggest that you review this knowledge base article; it will guide you through the necessary configurations. You could skip FreeRTOS and using a dedicated timer as a time base, because from the snippet you attached above, your goal is to run LwIP in polling mode.

• Implementing a LwIP and FreeRTOS™ v1 UDP echo server on the STM32F7 series 

[STackPointer64]

Once we ensure that LwIP is working flawlessly, we can move on and debug why the LWIP_NETIF_LINK_CALLBACK function is not being triggered and does not print any message.

[NicRoberts]

I'll go through the link you posted. Thanks for taking a look, find attached. 

[Andrew Neil]

---

@NicRoberts wrote:

doesn't get past the memory initialisation, 

---

So the code is not completing initialisation at all ?

Hardly surprising, then, that none of the features work!

Debugging Cortex-M Hard Faults

LwIP Debug / Diagnostics

[STackPointer64]

As suspected, you are missing crucial memory and cache configurations that will allow your application to work. I suggest that, after reading the article, you apply the configurations illustrated in sections 2.2, 2.4, 2.5, and 3.1. I’m pretty sure they will resolve the issue you are currently facing.