stm32下lwip使用DHCP实现自动获取IP地址的设计

lwip_v1.4.1 首先在lwip找到

opt.h 里将 #define LWIP_ARP                        1 //值1使能

    /*
   ----------------------------------
   ---------- DHCP options ----------
   ----------------------------------
*/
/**
 * LWIP_DHCP==1: Enable DHCP module.
 */
#ifndef LWIP_DHCP
#define LWIP_DHCP                       1 //为1 使能
#endif
在sourceinsight  下进入定义中在lwipopts.h中也要使能。

#define LWIP_DHCP               1
//#define DHCP_DOES_ARP_CHECK     1

#define USE_DHCP                 1   定义这个

初始化

   ETH_BSP_Config();  
    LwIP_Init();
在LwIP_Init函数中 会自动完成

 #ifdef USE_DHCP
  ipaddr.addr = 0;
  netmask.addr = 0;
  gw.addr = 0;
#else
  IP4_ADDR(&ipaddr, IP_ADDR0, IP_ADDR1, IP_ADDR2, IP_ADDR3);
  IP4_ADDR(&netmask, NETMASK_ADDR0, NETMASK_ADDR1 , NETMASK_ADDR2, NETMASK_ADDR3);
  IP4_ADDR(&gw, GW_ADDR0, GW_ADDR1, GW_ADDR2, GW_ADDR3);
#endif  
  
#endif

  /* - netif_add(struct netif *netif, struct ip_addr *ipaddr,
  struct ip_addr *netmask, struct ip_addr *gw,
  void *state, err_t (* init)(struct netif *netif),
  err_t (* input)(struct pbuf *p, struct netif *netif))

  Adds your network interface to the netif_list. Allocate a struct
  netif and pass a pointer to this structure as the first argument.
  Give pointers to cleared ip_addr structures when using DHCP,
  or fill them with sane numbers otherwise. The state pointer may be NULL.

  The init function pointer must point to a initialization function for
  your ethernet netif interface. The following code illustrates it's use.*/
  netif_add(&gnetif, &ipaddr, &netmask, &gw, NULL, &ethernetif_init, &ethernet_input);

  /*  Registers the default network interface.*/
  netif_set_default(&gnetif);

  if (EthStatus == (ETH_INIT_FLAG | ETH_LINK_FLAG))
  {
    /* Set Ethernet link flag */
    gnetif.flags |= NETIF_FLAG_LINK_UP;

    /* When the netif is fully configured this function must be called */
    netif_set_up(&gnetif);

最后在netconf.c中找到

void LwIP_DHCP_Process_Handle()

{
  struct ip_addr ipaddr;
  struct ip_addr netmask;
  struct ip_addr gw;
  uint8_t iptab[4] = {0};
  uint8_t iptxt[20];
  
  switch (DHCP_state)
  {
  case DHCP_START:
    {
      DHCP_state = DHCP_WAIT_ADDRESS;
      dhcp_start(&gnetif);
      /* IP address should be set to 0 
         every time we want to assign a new DHCP address */
      IPaddress = 0;
#ifdef USE_LCD
      LCD_DisplayStringLine(Line4, (uint8_t*)"     Looking for    ");
      LCD_DisplayStringLine(Line5, (uint8_t*)"     DHCP server    ");
      LCD_DisplayStringLine(Line6, (uint8_t*)"     please wait... ");
#endif
    }
    break;

  case DHCP_WAIT_ADDRESS:
    {
      /* Read the new IP address */
      IPaddress = gnetif.ip_addr.addr;
      
      if (IPaddress!=0) 
      {
        DHCP_state = DHCP_ADDRESS_ASSIGNED;
        
        /* Stop DHCP */
        dhcp_stop(&gnetif);

#ifdef USE_LCD      
        iptab[0] = (uint8_t)(IPaddress >> 24);
        iptab[1] = (uint8_t)(IPaddress >> 16);
        iptab[2] = (uint8_t)(IPaddress >> 8);
        iptab[3] = (uint8_t)(IPaddress);

        sprintf((char*)iptxt, " %d.%d.%d.%d", iptab[3], iptab[2], iptab[1], iptab[0]);       

        LCD_ClearLine(Line4);
        LCD_ClearLine(Line5);
        LCD_ClearLine(Line6);

        /* Display the IP address */
        LCD_DisplayStringLine(Line7, (uint8_t*)"IP address assigned ");
        LCD_DisplayStringLine(Line8, (uint8_t*)"  by a DHCP server  ");
        LCD_DisplayStringLine(Line9, iptxt);
#endif
        STM_EVAL_LEDOn(LED1);
      }
      else
      {
        /* DHCP timeout */
        if (gnetif.dhcp->tries > MAX_DHCP_TRIES)
        {
          DHCP_state = DHCP_TIMEOUT;

          /* Stop DHCP */
          dhcp_stop(&gnetif);

          /* Static address used */
          IP4_ADDR(&ipaddr, IP_ADDR0 ,IP_ADDR1 , IP_ADDR2 , IP_ADDR3 );
          IP4_ADDR(&netmask, NETMASK_ADDR0, NETMASK_ADDR1, NETMASK_ADDR2, NETMASK_ADDR3);
          IP4_ADDR(&gw, GW_ADDR0, GW_ADDR1, GW_ADDR2, GW_ADDR3);
          netif_set_addr(&gnetif, &ipaddr , &netmask, &gw);

#ifdef USE_LCD   
          LCD_DisplayStringLine(Line7, (uint8_t*)"    DHCP timeout    ");

          iptab[0] = IP_ADDR3;
          iptab[1] = IP_ADDR2;
          iptab[2] = IP_ADDR1;
          iptab[3] = IP_ADDR0;

          sprintf((char*)iptxt, "  %d.%d.%d.%d", iptab[3], iptab[2], iptab[1], iptab[0]);

          LCD_ClearLine(Line4);
          LCD_ClearLine(Line5);
          LCD_ClearLine(Line6);

          LCD_DisplayStringLine(Line8, (uint8_t*)"  Static IP address   ");
          LCD_DisplayStringLine(Line9, iptxt);         
#endif
          STM_EVAL_LEDOn(LED1);
        }
      }
    }
    break;
  default: break;
  }
}