LWIP with Ethernet Cable Disconnected

[xianrecords]

I am using a Nucleo-F429ZI with FreeRtos and LWIP.

I am having an issue with LWIP when I start with a disconnected Ethernet Cable and then when I connect it back when the firmware is running.

I have a thread with the following code.

1 - The gnetif structure is initialized by MX_LWIP_Init(). But the function check 

netif_is_up(&gnetif)

returns that the link is up even though the cable is disconnected.

2 - When I plug the cable back, the DHCP function does not acquire an IP Address. It seems stuck somewhere

3 - When the cable is connected and then I disconnect it, the gnetif.ip_addr.addr stays with the initial DHCP address instead of resetting to 0.

Any thoughts on what the issues might be ?

MX_LWIP_Init();

/* USER CODE BEGIN 5 */

firstTime = 1;

/* Infinite loop */

for(;;)

{

     while (timer_update == 0);

    timer_update = 0;

   if (netif_is_up(&gnetif)) {

     printf("Main Link is Up\n");

  } else {

    printf("Main Link is Down\n");

    continue;

  }

   local_IP = gnetif.ip_addr.addr;

  if (local_IP == 0) continue;

     printf("IP Address: %s\n", ip4addr_ntoa(&gnetif.ip_addr));

    if (client == NULL) client = mqtt_client_new();

    osDelay(100);

    if(client != NULL) {

       if (!mqtt_client_is_connected(client)) {

          printf("Connecting to Client\n\r");

          corin_do_connect(client,local_IP);

      } else {

         corin_publish(client,"This is a Test");

     }

     osDelay(100);

  }

}

[xianrecords]

So I thought I figured out the issue for number 1 by adding the following to lwip.c in the MX_LWIP_Init function but now the link never updates to Link Up when I plug the cable back in

/* We must always bring the network interface up connection or not... */

if (netif_is_link_up(&gnetif))

{

/* When the netif is fully configured this function must be called */

netif_set_up(&gnetif);

}

else

{

/* When the netif link is down this function must be called */

netif_set_down(&gnetif);

}

[Bob S]

This is usually an issue with the ethernetif_set_link() function/task that does not properly call netif_set_link_up() and netif_set_link_down() as the interface goes up and down (i.e. cable plugged and unplugged).  Something like this:

// WARNING - HAND TYPED MAY NOT BE 100% CORRECT
// but you get the idea

// Inside ethernetif_set_link()
for(;;)
{
  HAL_ETH_ReadPHYRegister(..., &regvalue );
  regvalue &= PHY_LINKED_STATUS;
  if ( !netif_is_link_up(link_arg->netif) && (regvalue) )
  {
    netif_set_link_up(link_arg->netif);
  }
  else if ( netif_is_link_up(link_arg->netif) && (!regvalue) )
  {
    netif_set_link_down(link_arg->netif);
  }
  // Other stuff may be here
}

[xianrecords · Accepted solution]

So I finally found the issue. The EthLink thread in lwip.c was set with a priority belowNormal and with my other thread ended up starving. So by setting it to Normal, it worked fine

memset(&attributes, 0x0, sizeof(osThreadAttr_t));

attributes.name = "EthLink";

attributes.stack_size = INTERFACE_THREAD_STACK_SIZE;

attributes.priority = osPriorityNormal;

osThreadNew(ethernet_link_thread, &gnetif, &attributes);