🌈

examples/.cargo/config.toml

@@ -0,0 +1,8 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+runner = "probe-rs-cli run --chip RP2040"
+
+[build]
+target = "thumbv6m-none-eabi"
+
+[env]
+DEFMT_LOG = "info"

examples/Cargo.toml

@@ -0,0 +1,70 @@
+[package]
+name = "embassy-net-w5500-examples"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+embassy-executor = { version = "0.1.0",  features = ["defmt", "integrated-timers", "executor-thread", "arch-cortex-m"] }
+embassy-time = { version = "0.1.0",  features = ["defmt", "defmt-timestamp-uptime"] }
+embassy-rp = { version = "0.1.0",  features = ["defmt", "unstable-traits", "nightly", "unstable-pac", "time-driver"] }
+embassy-net = { version = "0.1.0", features = ["defmt", "tcp", "udp", "dhcpv4", "medium-ethernet", "unstable-traits", "nightly"] }
+embassy-sync = { version = "0.1.0" }
+embassy-futures = { version = "0.1.0" }
+embassy-net-driver = { version = "0.1.0" }
+embassy-net-driver-channel = { version = "0.1.0" }
+atomic-polyfill = "0.1.5"
+static_cell = "1.0"
+
+defmt = "=0.3.2"
+defmt-rtt = "0.3"
+panic-probe = { version = "0.3", features = ["print-defmt"] }
+cortex-m = { version = "0.7.6", features = ["critical-section-single-core"] }
+cortex-m-rt = "0.7.0"
+
+embedded-io = { version = "0.4.0", features = ["async", "defmt"] }
+heapless = "0.7.15"
+embedded-hal = { version = "1.0.0-alpha.10" }
+embedded-hal-async = { version = "=0.2.0-alpha.1" }
+rand = { version = "0.8.5", default-features = false }
+
+embassy-net-w5500 = { path = "../" }
+
+[patch.crates-io]
+embassy-executor = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-time = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-futures = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-sync = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-rp = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-net = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-net-driver = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+embassy-net-driver-channel = { git = "https://github.com/embassy-rs/embassy", rev = "03d6363d5af5dcaf21b52734994a466ca593d2b6" }
+
+[profile.dev]
+debug = 2
+debug-assertions = true
+opt-level = 1
+overflow-checks = true
+
+[profile.release]
+codegen-units = 1
+debug = 1
+debug-assertions = false
+incremental = false
+lto = 'fat'
+opt-level = 'z'
+overflow-checks = false
+
+# do not optimize proc-macro crates = faster builds from scratch
+[profile.dev.build-override]
+codegen-units = 8
+debug = false
+debug-assertions = false
+opt-level = 0
+overflow-checks = false
+
+[profile.release.build-override]
+codegen-units = 8
+debug = false
+debug-assertions = false
+opt-level = 0
+overflow-checks = false

examples/README.md

@@ -0,0 +1,33 @@
+# Examples for the rp2040 `WIZnet W5500-EVB-Pico` board
+
+Examples are written for the [`WIZnet W5500-EVB-Pico`](https://www.wiznet.io/product-item/w5500-evb-pico/) board.
+
+## Prerequisites
+```bash
+cargo install probe-rs-cli
+```
+
+## TCP server example
+```bash
+cargo run --bin tcp-server --release
+```
+This example implements a TCP echo server on port 1234 and using DHCP.
+Send it some data, you should see it echoed back and printed in the console.
+
+## Multi-socket example
+```bash
+cargo run --bin multisocket --release
+```
+This example shows how you can allow multiple simultaneous TCP connections, by having multiple sockets listening on the same port.
+
+## TCP client example
+```bash
+cargo run --bin tcp-client --release
+```
+This example implements a TCP client that attempts to connect to a host on port 1234 and send it some data once per second.
+
+## UDP server example
+```bash
+cargo run --bin udp --release
+```
+This example implements a UDP server listening on port 1234 and echoing back the data.

examples/build.rs

@@ -0,0 +1,36 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    println!("cargo:rustc-link-arg-bins=-Tlink-rp.x");
+    println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+}

examples/memory.x

@@ -0,0 +1,5 @@
+MEMORY {
+    BOOT2 : ORIGIN = 0x10000000, LENGTH = 0x100
+    FLASH : ORIGIN = 0x10000100, LENGTH = 1024K - 0x100
+    RAM   : ORIGIN = 0x20000000, LENGTH = 256K
+}

examples/src/bin/multisocket.rs

@@ -0,0 +1,148 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_futures::yield_now;
+use embassy_net::{Stack, StackResources};
+use embassy_net_w5500::*;
+use embassy_rp::clocks::RoscRng;
+use embassy_rp::gpio::{Input, Level, Output, Pull};
+use embassy_rp::peripherals::{PIN_17, PIN_20, PIN_21, SPI0};
+use embassy_rp::spi::{Async, Config as SpiConfig, Spi};
+use embedded_hal_async::spi::ExclusiveDevice;
+use embedded_io::asynch::Write;
+use rand::RngCore;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+macro_rules! singleton {
+    ($val:expr) => {{
+        type T = impl Sized;
+        static STATIC_CELL: StaticCell<T> = StaticCell::new();
+        let (x,) = STATIC_CELL.init(($val,));
+        x
+    }};
+}
+
+#[embassy_executor::task]
+async fn ethernet_task(
+    runner: Runner<
+        'static,
+        ExclusiveDevice<Spi<'static, SPI0, Async>, Output<'static, PIN_17>>,
+        Input<'static, PIN_21>,
+        Output<'static, PIN_20>,
+    >,
+) -> ! {
+    runner.run().await
+}
+
+#[embassy_executor::task]
+async fn net_task(stack: &'static Stack<Device<'static>>) -> ! {
+    stack.run().await
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let mut rng = RoscRng;
+
+    let mut spi_cfg = SpiConfig::default();
+    spi_cfg.frequency = 50_000_000;
+    let (miso, mosi, clk) = (p.PIN_16, p.PIN_19, p.PIN_18);
+    let spi = Spi::new(p.SPI0, clk, mosi, miso, p.DMA_CH0, p.DMA_CH1, spi_cfg);
+    let cs = Output::new(p.PIN_17, Level::High);
+    let w5500_int = Input::new(p.PIN_21, Pull::Up);
+    let w5500_reset = Output::new(p.PIN_20, Level::High);
+
+    let mac_addr = [0x02, 0x00, 0x00, 0x00, 0x00, 0x00];
+    let state = singleton!(State::<8, 8>::new());
+    let (device, runner) = embassy_net_w5500::new(
+        mac_addr,
+        state,
+        ExclusiveDevice::new(spi, cs),
+        w5500_int,
+        w5500_reset,
+    )
+    .await;
+    unwrap!(spawner.spawn(ethernet_task(runner)));
+
+    // Generate random seed
+    let seed = rng.next_u64();
+
+    // Init network stack
+    let stack = &*singleton!(Stack::new(
+        device,
+        embassy_net::Config::Dhcp(Default::default()),
+        singleton!(StackResources::<3>::new()),
+        seed
+    ));
+
+    // Launch network task
+    unwrap!(spawner.spawn(net_task(&stack)));
+
+    info!("Waiting for DHCP...");
+    let cfg = wait_for_config(stack).await;
+    let local_addr = cfg.address.address();
+    info!("IP address: {:?}", local_addr);
+
+    // Create two sockets listening to the same port, to handle simultaneous connections
+    unwrap!(spawner.spawn(listen_task(&stack, 0, 1234)));
+    unwrap!(spawner.spawn(listen_task(&stack, 1, 1234)));
+}
+
+#[embassy_executor::task(pool_size = 2)]
+async fn listen_task(stack: &'static Stack<Device<'static>>, id: u8, port: u16) {
+    let mut rx_buffer = [0; 4096];
+    let mut tx_buffer = [0; 4096];
+    let mut buf = [0; 4096];
+    loop {
+        let mut socket = embassy_net::tcp::TcpSocket::new(stack, &mut rx_buffer, &mut tx_buffer);
+        socket.set_timeout(Some(embassy_net::SmolDuration::from_secs(10)));
+
+        info!("SOCKET {}: Listening on TCP:{}...", id, port);
+        if let Err(e) = socket.accept(port).await {
+            warn!("accept error: {:?}", e);
+            continue;
+        }
+        info!(
+            "SOCKET {}: Received connection from {:?}",
+            id,
+            socket.remote_endpoint()
+        );
+
+        loop {
+            let n = match socket.read(&mut buf).await {
+                Ok(0) => {
+                    warn!("read EOF");
+                    break;
+                }
+                Ok(n) => n,
+                Err(e) => {
+                    warn!("SOCKET {}: {:?}", id, e);
+                    break;
+                }
+            };
+            info!(
+                "SOCKET {}: rxd {}",
+                id,
+                core::str::from_utf8(&buf[..n]).unwrap()
+            );
+
+            if let Err(e) = socket.write_all(&buf[..n]).await {
+                warn!("write error: {:?}", e);
+                break;
+            }
+        }
+    }
+}
+
+async fn wait_for_config(stack: &'static Stack<Device<'static>>) -> embassy_net::StaticConfig {
+    loop {
+        if let Some(config) = stack.config() {
+            return config.clone();
+        }
+        yield_now().await;
+    }
+}

examples/src/bin/tcp-client.rs

@@ -0,0 +1,128 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use core::str::FromStr;
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_futures::yield_now;
+use embassy_net::{Stack, StackResources};
+use embassy_net_w5500::*;
+use embassy_rp::clocks::RoscRng;
+use embassy_rp::gpio::{Input, Level, Output, Pull};
+use embassy_rp::peripherals::{PIN_17, PIN_20, PIN_21, SPI0};
+use embassy_rp::spi::{Async, Config as SpiConfig, Spi};
+use embassy_time::{Duration, Timer};
+use embedded_hal_async::spi::ExclusiveDevice;
+use embedded_io::asynch::Write;
+use rand::RngCore;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+macro_rules! singleton {
+    ($val:expr) => {{
+        type T = impl Sized;
+        static STATIC_CELL: StaticCell<T> = StaticCell::new();
+        let (x,) = STATIC_CELL.init(($val,));
+        x
+    }};
+}
+
+#[embassy_executor::task]
+async fn ethernet_task(
+    runner: Runner<
+        'static,
+        ExclusiveDevice<Spi<'static, SPI0, Async>, Output<'static, PIN_17>>,
+        Input<'static, PIN_21>,
+        Output<'static, PIN_20>,
+    >,
+) -> ! {
+    runner.run().await
+}
+
+#[embassy_executor::task]
+async fn net_task(stack: &'static Stack<Device<'static>>) -> ! {
+    stack.run().await
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let mut rng = RoscRng;
+    let mut led = Output::new(p.PIN_25, Level::Low);
+
+    let mut spi_cfg = SpiConfig::default();
+    spi_cfg.frequency = 50_000_000;
+    let (miso, mosi, clk) = (p.PIN_16, p.PIN_19, p.PIN_18);
+    let spi = Spi::new(p.SPI0, clk, mosi, miso, p.DMA_CH0, p.DMA_CH1, spi_cfg);
+    let cs = Output::new(p.PIN_17, Level::High);
+    let w5500_int = Input::new(p.PIN_21, Pull::Up);
+    let w5500_reset = Output::new(p.PIN_20, Level::High);
+
+    let mac_addr = [0x02, 0x00, 0x00, 0x00, 0x00, 0x00];
+    let state = singleton!(State::<8, 8>::new());
+    let (device, runner) = embassy_net_w5500::new(
+        mac_addr,
+        state,
+        ExclusiveDevice::new(spi, cs),
+        w5500_int,
+        w5500_reset,
+    )
+    .await;
+    unwrap!(spawner.spawn(ethernet_task(runner)));
+
+    // Generate random seed
+    let seed = rng.next_u64();
+
+    // Init network stack
+    let stack = &*singleton!(Stack::new(
+        device,
+        embassy_net::Config::Dhcp(Default::default()),
+        singleton!(StackResources::<2>::new()),
+        seed
+    ));
+
+    // Launch network task
+    unwrap!(spawner.spawn(net_task(&stack)));
+
+    info!("Waiting for DHCP...");
+    let cfg = wait_for_config(stack).await;
+    let local_addr = cfg.address.address();
+    info!("IP address: {:?}", local_addr);
+
+    let mut rx_buffer = [0; 4096];
+    let mut tx_buffer = [0; 4096];
+    loop {
+        let mut socket = embassy_net::tcp::TcpSocket::new(stack, &mut rx_buffer, &mut tx_buffer);
+        socket.set_timeout(Some(embassy_net::SmolDuration::from_secs(10)));
+
+        led.set_low();
+        info!("Connecting...");
+        let host_addr = embassy_net::Ipv4Address::from_str("192.168.1.110").unwrap();
+        if let Err(e) = socket.connect((host_addr, 1234)).await {
+            warn!("connect error: {:?}", e);
+            continue;
+        }
+        info!("Connected to {:?}", socket.remote_endpoint());
+        led.set_high();
+
+        let msg = b"Hello world!\n";
+        loop {
+            if let Err(e) = socket.write_all(msg).await {
+                warn!("write error: {:?}", e);
+                break;
+            }
+            info!("txd: {}", core::str::from_utf8(msg).unwrap());
+            Timer::after(Duration::from_secs(1)).await;
+        }
+    }
+}
+
+async fn wait_for_config(stack: &'static Stack<Device<'static>>) -> embassy_net::StaticConfig {
+    loop {
+        if let Some(config) = stack.config() {
+            return config.clone();
+        }
+        yield_now().await;
+    }
+}

examples/src/bin/tcp-server.rs

@@ -0,0 +1,136 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_futures::yield_now;
+use embassy_net::{Stack, StackResources};
+use embassy_net_w5500::*;
+use embassy_rp::clocks::RoscRng;
+use embassy_rp::gpio::{Input, Level, Output, Pull};
+use embassy_rp::peripherals::{PIN_17, PIN_20, PIN_21, SPI0};
+use embassy_rp::spi::{Async, Config as SpiConfig, Spi};
+use embedded_hal_async::spi::ExclusiveDevice;
+use embedded_io::asynch::Write;
+use rand::RngCore;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+macro_rules! singleton {
+    ($val:expr) => {{
+        type T = impl Sized;
+        static STATIC_CELL: StaticCell<T> = StaticCell::new();
+        let (x,) = STATIC_CELL.init(($val,));
+        x
+    }};
+}
+
+#[embassy_executor::task]
+async fn ethernet_task(
+    runner: Runner<
+        'static,
+        ExclusiveDevice<Spi<'static, SPI0, Async>, Output<'static, PIN_17>>,
+        Input<'static, PIN_21>,
+        Output<'static, PIN_20>,
+    >,
+) -> ! {
+    runner.run().await
+}
+
+#[embassy_executor::task]
+async fn net_task(stack: &'static Stack<Device<'static>>) -> ! {
+    stack.run().await
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let mut rng = RoscRng;
+    let mut led = Output::new(p.PIN_25, Level::Low);
+
+    let mut spi_cfg = SpiConfig::default();
+    spi_cfg.frequency = 50_000_000;
+    let (miso, mosi, clk) = (p.PIN_16, p.PIN_19, p.PIN_18);
+    let spi = Spi::new(p.SPI0, clk, mosi, miso, p.DMA_CH0, p.DMA_CH1, spi_cfg);
+    let cs = Output::new(p.PIN_17, Level::High);
+    let w5500_int = Input::new(p.PIN_21, Pull::Up);
+    let w5500_reset = Output::new(p.PIN_20, Level::High);
+
+    let mac_addr = [0x02, 0x00, 0x00, 0x00, 0x00, 0x00];
+    let state = singleton!(State::<8, 8>::new());
+    let (device, runner) = embassy_net_w5500::new(
+        mac_addr,
+        state,
+        ExclusiveDevice::new(spi, cs),
+        w5500_int,
+        w5500_reset,
+    )
+    .await;
+    unwrap!(spawner.spawn(ethernet_task(runner)));
+
+    // Generate random seed
+    let seed = rng.next_u64();
+
+    // Init network stack
+    let stack = &*singleton!(Stack::new(
+        device,
+        embassy_net::Config::Dhcp(Default::default()),
+        singleton!(StackResources::<2>::new()),
+        seed
+    ));
+
+    // Launch network task
+    unwrap!(spawner.spawn(net_task(&stack)));
+
+    info!("Waiting for DHCP...");
+    let cfg = wait_for_config(stack).await;
+    let local_addr = cfg.address.address();
+    info!("IP address: {:?}", local_addr);
+
+    let mut rx_buffer = [0; 4096];
+    let mut tx_buffer = [0; 4096];
+    let mut buf = [0; 4096];
+    loop {
+        let mut socket = embassy_net::tcp::TcpSocket::new(stack, &mut rx_buffer, &mut tx_buffer);
+        socket.set_timeout(Some(embassy_net::SmolDuration::from_secs(10)));
+
+        led.set_low();
+        info!("Listening on TCP:1234...");
+        if let Err(e) = socket.accept(1234).await {
+            warn!("accept error: {:?}", e);
+            continue;
+        }
+        info!("Received connection from {:?}", socket.remote_endpoint());
+        led.set_high();
+
+        loop {
+            let n = match socket.read(&mut buf).await {
+                Ok(0) => {
+                    warn!("read EOF");
+                    break;
+                }
+                Ok(n) => n,
+                Err(e) => {
+                    warn!("{:?}", e);
+                    break;
+                }
+            };
+            info!("rxd {}", core::str::from_utf8(&buf[..n]).unwrap());
+
+            if let Err(e) = socket.write_all(&buf[..n]).await {
+                warn!("write error: {:?}", e);
+                break;
+            }
+        }
+    }
+}
+
+async fn wait_for_config(stack: &'static Stack<Device<'static>>) -> embassy_net::StaticConfig {
+    loop {
+        if let Some(config) = stack.config() {
+            return config.clone();
+        }
+        yield_now().await;
+    }
+}

examples/src/bin/udp.rs

@@ -0,0 +1,123 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_futures::yield_now;
+use embassy_net::udp::UdpSocket;
+use embassy_net::{PacketMetadata, Stack, StackResources};
+use embassy_net_w5500::*;
+use embassy_rp::clocks::RoscRng;
+use embassy_rp::gpio::{Input, Level, Output, Pull};
+use embassy_rp::peripherals::{PIN_17, PIN_20, PIN_21, SPI0};
+use embassy_rp::spi::{Async, Config as SpiConfig, Spi};
+use embedded_hal_async::spi::ExclusiveDevice;
+use rand::RngCore;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+macro_rules! singleton {
+    ($val:expr) => {{
+        type T = impl Sized;
+        static STATIC_CELL: StaticCell<T> = StaticCell::new();
+        let (x,) = STATIC_CELL.init(($val,));
+        x
+    }};
+}
+
+#[embassy_executor::task]
+async fn ethernet_task(
+    runner: Runner<
+        'static,
+        ExclusiveDevice<Spi<'static, SPI0, Async>, Output<'static, PIN_17>>,
+        Input<'static, PIN_21>,
+        Output<'static, PIN_20>,
+    >,
+) -> ! {
+    runner.run().await
+}
+
+#[embassy_executor::task]
+async fn net_task(stack: &'static Stack<Device<'static>>) -> ! {
+    stack.run().await
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let mut rng = RoscRng;
+
+    let mut spi_cfg = SpiConfig::default();
+    spi_cfg.frequency = 50_000_000;
+    let (miso, mosi, clk) = (p.PIN_16, p.PIN_19, p.PIN_18);
+    let spi = Spi::new(p.SPI0, clk, mosi, miso, p.DMA_CH0, p.DMA_CH1, spi_cfg);
+    let cs = Output::new(p.PIN_17, Level::High);
+    let w5500_int = Input::new(p.PIN_21, Pull::Up);
+    let w5500_reset = Output::new(p.PIN_20, Level::High);
+
+    let mac_addr = [0x02, 0x00, 0x00, 0x00, 0x00, 0x00];
+    let state = singleton!(State::<8, 8>::new());
+    let (device, runner) = embassy_net_w5500::new(
+        mac_addr,
+        state,
+        ExclusiveDevice::new(spi, cs),
+        w5500_int,
+        w5500_reset,
+    )
+    .await;
+    unwrap!(spawner.spawn(ethernet_task(runner)));
+
+    // Generate random seed
+    let seed = rng.next_u64();
+
+    // Init network stack
+    let stack = &*singleton!(Stack::new(
+        device,
+        embassy_net::Config::Dhcp(Default::default()),
+        singleton!(StackResources::<2>::new()),
+        seed
+    ));
+
+    // Launch network task
+    unwrap!(spawner.spawn(net_task(&stack)));
+
+    info!("Waiting for DHCP...");
+    let cfg = wait_for_config(stack).await;
+    let local_addr = cfg.address.address();
+    info!("IP address: {:?}", local_addr);
+
+    // Then we can use it!
+    let mut rx_buffer = [0; 4096];
+    let mut tx_buffer = [0; 4096];
+    let mut rx_meta = [PacketMetadata::EMPTY; 16];
+    let mut tx_meta = [PacketMetadata::EMPTY; 16];
+    let mut buf = [0; 4096];
+    loop {
+        let mut socket = UdpSocket::new(
+            stack,
+            &mut rx_meta,
+            &mut rx_buffer,
+            &mut tx_meta,
+            &mut tx_buffer,
+        );
+        socket.bind(1234).unwrap();
+
+        loop {
+            let (n, ep) = socket.recv_from(&mut buf).await.unwrap();
+            if let Ok(s) = core::str::from_utf8(&buf[..n]) {
+                info!("rxd from {}: {}", ep, s);
+            }
+            socket.send_to(&buf[..n], ep).await.unwrap();
+        }
+    }
+}
+
+async fn wait_for_config(stack: &'static Stack<Device<'static>>) -> embassy_net::StaticConfig {
+    loop {
+        if let Some(config) = stack.config() {
+            return config.clone();
+        }
+        yield_now().await;
+    }
+}