Wi-Fi Module

Wi-Fi connection setup

The Wi-Fi setup code is the same as explained in the "Connecting Wi-Fi with Embassy" chapter on the Access Website. To avoid repetition, I won't explain it again here. Please refer to that chapter if you haven't already.

#![allow(unused)]
fn main() {
const SSID: &str = env!("SSID");
const PASSWORD: &str = env!("PASSWORD");

}

Start Wi-Fi

The start_wifi function is responsible for setting up and starting the Wi-Fi connection for the ESP32. Here's a step-by-step explanation:

1. We will create the Wi-Fi interface and controller in STA (Station) mode so the ESP32 can connect to an existing Wi-Fi network.

2. Normally, when a device connects to a Wi-Fi network, the router assigns it an IP address automatically using DHCP Server. In this exercise, we will configure the ESP32 to request DHCP for IP.
   To achieve this, we will create a net_config instance configured for DHCP. Then, we will use this configuration along with the Wi-Fi interface to initialize the network stack and runner instances.

3. We will spawn two tasks:

   • The connection task to monitor the Wi-Fi connection and reconnect, if it is disconnected.
   • The network task to manage all network communications.

4. We will wait until the Wi-Fi link is up. Once the connection is ready, we will print the IP address assigned to our ESP32.

5. Finally, we will return the network stack instance. This will be used later by the web task to handle web server operations.

#![allow(unused)]

fn main() {
pub async fn start_wifi(
    wifi_init: &'static EspWifiController<'static>,
    wifi: esp_hal::peripherals::WIFI,
    mut rng: Rng,
    spawner: &Spawner,
) -> &'static Stack<'static> {
    let (wifi_interface, controller) =
        esp_wifi::wifi::new_with_mode(&wifi_init, wifi, WifiStaDevice).unwrap();
    let net_seed = rng.random() as u64 | ((rng.random() as u64) << 32);

    let dhcp_config = DhcpConfig::default();
    let net_config = embassy_net::Config::dhcpv4(dhcp_config);

    let (stack, runner) = mk_static!(
        (
            Stack<'static>,
            Runner<'static, WifiDevice<'static, WifiStaDevice>>
        ),
        embassy_net::new(
            wifi_interface,
            net_config,
            mk_static!(StackResources<3>, StackResources::<3>::new()),
            net_seed
        )
    );

    spawner.spawn(connection_task(controller)).ok();
    spawner.spawn(net_task(runner)).ok();

    loop {
        if stack.is_link_up() {
            break;
        }
        Timer::after(Duration::from_millis(500)).await;
    }

    println!("Waiting to get IP address...");
    loop {
        if let Some(config) = stack.config_v4() {
            println!("Got IP: {}", config.address);
            break;
        }
        Timer::after(Duration::from_millis(500)).await;
    }

    stack
}
}

Wi-Fi and Network Tasks

There is no major change in the logic of these two tasks. The only difference is that we are now passing the runner instance to the net_task, unlike before.

#![allow(unused)]
fn main() {
#[embassy_executor::task]
async fn connection_task(mut controller: WifiController<'static>) {
    println!("start connection task");
    println!("Device capabilities: {:?}", controller.capabilities());
    loop {
        match esp_wifi::wifi::wifi_state() {
            WifiState::StaConnected => {
                // wait until we're no longer connected
                controller.wait_for_event(WifiEvent::StaDisconnected).await;
                Timer::after(Duration::from_millis(5000)).await
            }
            _ => {}
        }
        if !matches!(controller.is_started(), Ok(true)) {
            let client_config = Configuration::Client(ClientConfiguration {
                ssid: SSID.try_into().unwrap(),
                password: PASSWORD.try_into().unwrap(),
                ..Default::default()
            });
            controller.set_configuration(&client_config).unwrap();
            println!("Starting wifi");
            controller.start_async().await.unwrap();
            println!("Wifi started!");
        }
        println!("About to connect...");

        match controller.connect_async().await {
            Ok(_) => println!("Wifi connected!"),
            Err(e) => {
                println!("Failed to connect to wifi: {e:?}");
                Timer::after(Duration::from_millis(5000)).await
            }
        }
    }
}
}

#![allow(unused)]
fn main() {
#[embassy_executor::task]
async fn net_task(runner: &'static mut Runner<'static, WifiDevice<'static, WifiStaDevice>>) -> ! {
    runner.run().await
}
}