5.11.1 Execution

main.c - Initialize the device and the USART interface. Create the TCP sockets, send/receive messages and display them on the terminal window.

  1. Code summary.
    • Configure the network parameters in main.h.
      /** Wi-Fi Settings */
#define MAIN_WLAN_SSID                    "DEMO_AP" /**< Destination SSID */
#define MAIN_WLAN_AUTH                    M2M_WIFI_SEC_WPA_PSK /**< Security type */
#define MAIN_WLAN_PSK                     "12345678" /**< Password for Destination SSID */
    • Configure the USART module to read user input data. 
      static void configure_console(void)
{
    ...
    stdio_serial_init(&cdc_uart_module, CONF_STDIO_USART_MODULE,&usart_conf);
	/* Register USART callback for receiving user input. */
    usart_register_callback(&cdc_uart_module, uart_callback, SART_CALLBACK_BUFFER_RECEIVED);
    usart_enable_callback(&cdc_uart_module, USART_CALLBACK_BUFFER_RECEIVED);
    usart_enable(&cdc_uart_module);
}
    • Initialize the socket module and register the socket callback function.
      /* Initialize socket module */
socketInit();
registerSocketCallback(socket_cb, resolve_cb);
    • Connect to the AP. 
      /* Connect to router. */
m2m_wifi_connect((char *)MAIN_WLAN_SSID, sizeof(MAIN_WLAN_SSID),
        MAIN_WLAN_AUTH, (char *)MAIN_WLAN_PSK, M2M_WIFI_CH_ALL);
    • After the device is connected to the AP, create the TCP server socket and bind it in the main loop. 
      if ((tcp_server_socket = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    continue;
}
...
bind(tcp_server_socket, (struct sockaddr *)&addr, sizeof(struct sockaddr_in));
    • If there is user input data, then the handle_input_message() function in the main loop calls the parse_command() function to parse the user data and execute the handler function according to the command. 
      uint8_t parse_command(char *buffer, uint8_t remote)
{
    for (i = i_st; i < i_ed; i++) {
        if (!strcmp(cmd_list[i].cmd_string, cmd_buf)) {
            cmd_list[i].cmd_handler(buffer + strlen(cmd_list[i].cmd_string) + 1);
            break;
        }
    }
    • The handle_input_message() function prints user data in the terminal window and sends it to the remote device.
      void handle_input_message(void)
{
    ...
    if (tcp_connected == 1) {
        PRINT_LOCAL_MSG(uart_buffer);
        send(tcp_client_socket, uart_buffer, msg_len + 1, 0);
    }
    • When receiving data from the remote device, it handles the received message to display it or execute a command.
    • There are several commands for Wi-Fi serial functionality in this example.
  2. Build the program and download it into the board.
  3. Start the application.
  4. Check the IP address of each board and execute the connection on one device by typing the <<connect xxx:xxx:xxx:xxx command on the terminal window with the other device's address. Use prefix "<<" to execute local commands.
  5. When connected, the socket_cb:connect success message will appear:
  6. Type messages on the terminal window and you will see the sent/received messages.
  7. You can control the LED on the remote device by typing the control ledon (Or) control ledoff command. Use prefix ">>" to execute remote commands.
  8. The application reads data from the serial interface. User commands can be modified to execute various actions.