Runtime Configuration

Each embedded ethernet device must have a unique MAC address, IP address, and host name. This is very important when multiple devices are connected to the same LAN. Otherwise, network collisions might occur, network communications on local LAN might be disturbed, and the system might not work.

You can use the same application code for serial production of embedded devices. The runtime configuration feature allows you to read configuration parameters from the EEPROM and configure the ethernet network interface for each embedded device differently.

• The MAC address is written to the ethernet controller registers when the controller initializes (when calling the function init_TcpNet()). For this reason, the variable own_hw_adr[6] must be set before the system initializes.
• The ethernet interface configuration parameters must be set after the system initializes. The structure localm[0] can simply be overwritten with new values.
• The local host name can be changed by overwriting the default value, which is set in the Net_Config.c system configuration file. The local host name accesses the embedded system by the name instead of the IP address.
• Dynamic Host Configuration can be disabled at runtime. In this case, user provided network parameters defined in the Net_Config.c configuration file are used instead. The DHCP Client can be disabled by calling the function dhcp_disable() after the system initializes. The DHCP Client must be enabled in the configuration so that the DHCP Client code links to the application code.

Here is an example of dynamic system configuration:

#include <Net_Config.h>

extern U8 own_hw_adr[];
extern U8 lhost_name[];
extern LOCALM localm[];

/* The following values are read out of EEPROM. */
U8 const mac_adr[6] = { 0,1,2,50,60,70 };
LOCALM const ip_config = {
  { 192,168,0,150 },             // IP address
  { 192,168,0,1 },               // Default Gateway
  { 255,255,255,0 },             // Net mask
  { 194,25,2,129 },              // Primary DNS server
  { 194,25,2,130 }               // Secondary DNS server
};
U8 const DHCP_mode = 0;
U8 const dev_name[16] = { "Keil_MCB" };

void main (void) {

  /* Change the MAC address */
  mem_copy (own_hw_adr, (U8 *)mac_adr, 6);

  init_TcpNet ();

  /* Change the host name */
  str_copy (lhost_name, (U8 *)dev_name);

  /* Change the IP address if dynamic mode is not used */
  if (DHCP_mode == 0) {
    dhcp_disable ();
    mem_copy ((U8 *)&localm[NETIF_ETH], (U8 *)&ip_config, sizeof(ip_config));
  }

  while (1) {
    timer_poll ();
    main_TcpNet ();
  }
}

In this example, the new parameters are defined in the code. However, in your application, this would be the network parameters read out from the EEPROM or NV RAM.

Note

• You can change the localm[NETIF_ETH] - ethernet IP parameters also when the system is working. See the HTTP_demo example. The ethernet controller MAC address can only be changed when the system starts. It is not advisable to change it later.