WiFi Connection

I. Experiment Objective

Learn the Wi-Fi networking function of the MicroROS-V2 control board. Through this experiment, you will master how to configure the ESP32 as a STA (Station) to connect to a router, handle connection and disconnection events, and configure the Wi-Fi SSID and password through the Kconfig menu.

II. Experiment Principle

1. Keywords

2. Technical Architecture

This example implements the STA-mode Wi-Fi networking function of the ESP32. After startup, the program initializes NVS Flash and the network interface, configures the Wi-Fi as STA mode and sets the SSID and password (read from Kconfig), starts Wi-Fi, and then automatically connects to the router through the event handling mechanism. After obtaining an IP address, it prints the connection information.

Main component files:

• main/main.c — Program entry, calls the Wi-Fi initialization
• components/wifi_sta/wifi_sta.c — Wi-Fi STA mode implementation
• components/wifi_sta/wifi_sta.h — Wi-Fi initialization function declarations
• components/wifi_sta/Kconfig.projbuild — menuconfig configuration item definitions

III. Experiment Steps

1. Hardware Preparation

2. Prerequisites

1. Set up the ESP32-IDF development environment
2. Connect the MicroROS-V2 control board to the computer via USB

3. Compile and Flash

Before compiling, you need to configure the Wi-Fi SSID and password through menuconfig:

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cd ~/esp/base_samples/wifi_sta
source ~/esp/esp-idf/export.sh
idf.py menuconfig
​

In the menu, go to Example Configuration and set the following two items:

• WiFi SSID: enter your router name

• WiFi Password: enter your Wi-Fi password

  

  After modifying, press S to save, then press Q to exit the configuration tool.

After configuration, compile and flash:

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​
cd ~/esp/base_samples/wifi_sta
source ~/esp/esp-idf/export.sh
idf.py build flash monitor
​

4. Stopping Method

In the terminal, press Ctrl+] to exit the serial monitor.

IV. Experiment Result

After successful compilation and flashing, the Monitor will output:

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hello yahboom
I (xxx) MAIN: Nice to meet you!
I (xxx) WIFI_STA: ESP_WIFI_MODE_STA
I (xxx) WIFI_STA: wifi_init_sta finished.
I (xxx) WIFI_STA: got ip:192.168.x.xxx
I (xxx) WIFI_STA: connected to ap SSID:your_ssid password:your_password

The control board successfully connects to the router and obtains an IP address, indicating that the Wi-Fi networking function works normally.

V. Program Analysis

Source code paths:

• Firmware source: ~/esp/base_samples/wifi_sta/main/main.c
• WiFi STA: ~/esp/base_samples/wifi_sta/components/wifi_sta/wifi_sta.h, wifi_sta.c
• Kconfig: ~/esp/base_samples/wifi_sta/components/wifi_sta/Kconfig.projbuild

1. Main Program Logic

main/main.c is the program entry. After printing a welcome message, it calls Wifi_Net_Init() to initialize Wi-Fi:

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#include "wifi_sta.h"
​
void app_main(void)
{
    printf("hello yahboom\n");
    ESP_LOGI(TAG, "Nice to meet you!");
    Wifi_Net_Init();
}

2. Wi-Fi Initialization Flow

The Wifi_Net_Init() function in components/wifi_sta/wifi_sta.c completes the full initialization flow:

1. Initialize NVS Flash — Call nvs_flash_init() to save the Wi-Fi configuration information

2. Call wifi_init_sta() — executes the following steps:

   • Create the event group s_wifi_event_group to notify the connection result
   • Call esp_netif_init() to initialize the network interface
   • Call esp_event_loop_create_default() to create the default event loop
   • Call esp_netif_create_default_wifi_sta() to create the default STA network interface
   • Call esp_wifi_init() to initialize the Wi-Fi driver
   • Register the Wi-Fi event and IP event handlers
   • Configure the Wi-Fi as STA mode and set the SSID and password
   • Call esp_wifi_start() to start Wi-Fi

3. Event Handling Mechanism

The event_handler() function handles three types of events:

The maximum retry count is configured through CONFIG_ESP_MAXIMUM_RETRY (default 5). If the connection still fails after exceeding the retry count, the failure flag WIFI_FAIL_BIT is set.

4. Wi-Fi Configuration Parameters

The Wi-Fi configuration struct is defined as follows:

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wifi_config_t wifi_config = {
    .sta = {
        .ssid = EXAMPLE_ESP_WIFI_SSID,       // Read from menuconfig
        .password = EXAMPLE_ESP_WIFI_PASS,    // Read from menuconfig
        .threshold.authmode = ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD,
        .sae_pwe_h2e = ESP_WIFI_SAE_MODE,
        .sae_h2e_identifier = EXAMPLE_H2E_IDENTIFIER,
    },
};

5. Kconfig Configuration Items

Parameter definition file: ~/esp/base_samples/wifi_sta/components/wifi_sta/Kconfig.projbuild

components/wifi_sta/Kconfig.projbuild defines the following parameters that can be configured through idf.py menuconfig:

6. Waiting for the Connection Result

wifi_init_sta() blocks and waits for the connection result through xEventGroupWaitBits():

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EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group,
        WIFI_CONNECTED_BIT | WIFI_FAIL_BIT,
        pdFALSE, pdFALSE, portMAX_DELAY);

• If WIFI_CONNECTED_BIT is set, the connection succeeded
• If WIFI_FAIL_BIT is set, the connection failed after exceeding the retry count

7. Key Components

VI. Common Problems