feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/embassy-net-driver-channel/src/fmt.rs

@@ -0,0 +1,270 @@
+#![macro_use]
+#![allow(unused)]
+
+use core::fmt::{Debug, Display, LowerHex};
+
+#[cfg(all(feature = "defmt", feature = "log"))]
+compile_error!("You may not enable both `defmt` and `log` features.");
+
+#[collapse_debuginfo(yes)]
+macro_rules! assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_eq!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_ne!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! debug_assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! debug_assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_eq!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! debug_assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_ne!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! todo {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::todo!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::todo!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! unreachable {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::unreachable!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::unreachable!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! panic {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::panic!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::panic!($($x)*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! trace {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::trace!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::trace!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! debug {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::debug!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! info {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::info!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::info!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! warn {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::warn!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::warn!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[collapse_debuginfo(yes)]
+macro_rules! error {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::error!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::error!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[cfg(feature = "defmt")]
+#[collapse_debuginfo(yes)]
+macro_rules! unwrap {
+    ($($x:tt)*) => {
+        ::defmt::unwrap!($($x)*)
+    };
+}
+
+#[cfg(not(feature = "defmt"))]
+#[collapse_debuginfo(yes)]
+macro_rules! unwrap {
+    ($arg:expr) => {
+        match $crate::fmt::Try::into_result($arg) {
+            ::core::result::Result::Ok(t) => t,
+            ::core::result::Result::Err(e) => {
+                ::core::panic!("unwrap of `{}` failed: {:?}", ::core::stringify!($arg), e);
+            }
+        }
+    };
+    ($arg:expr, $($msg:expr),+ $(,)? ) => {
+        match $crate::fmt::Try::into_result($arg) {
+            ::core::result::Result::Ok(t) => t,
+            ::core::result::Result::Err(e) => {
+                ::core::panic!("unwrap of `{}` failed: {}: {:?}", ::core::stringify!($arg), ::core::format_args!($($msg,)*), e);
+            }
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct NoneError;
+
+pub trait Try {
+    type Ok;
+    type Error;
+    fn into_result(self) -> Result<Self::Ok, Self::Error>;
+}
+
+impl<T> Try for Option<T> {
+    type Ok = T;
+    type Error = NoneError;
+
+    #[inline]
+    fn into_result(self) -> Result<T, NoneError> {
+        self.ok_or(NoneError)
+    }
+}
+
+impl<T, E> Try for Result<T, E> {
+    type Ok = T;
+    type Error = E;
+
+    #[inline]
+    fn into_result(self) -> Self {
+        self
+    }
+}
+
+pub(crate) struct Bytes<'a>(pub &'a [u8]);
+
+impl<'a> Debug for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+impl<'a> Display for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+impl<'a> LowerHex for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl<'a> defmt::Format for Bytes<'a> {
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "{:02x}", self.0)
+    }
+}

vendor/embassy-net-driver-channel/src/lib.rs

@@ -0,0 +1,410 @@
+#![no_std]
+#![doc = include_str!("../README.md")]
+#![warn(missing_docs)]
+
+// must go first!
+mod fmt;
+
+use core::cell::RefCell;
+use core::mem::MaybeUninit;
+use core::task::{Context, Poll};
+
+pub use embassy_net_driver as driver;
+use embassy_net_driver::{Capabilities, LinkState};
+use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+use embassy_sync::blocking_mutex::Mutex;
+use embassy_sync::waitqueue::WakerRegistration;
+use embassy_sync::zerocopy_channel;
+
+/// Channel state.
+///
+/// Holds a buffer of packets with size MTU, for both TX and RX.
+pub struct State<const MTU: usize, const N_RX: usize, const N_TX: usize> {
+    rx: [PacketBuf<MTU>; N_RX],
+    tx: [PacketBuf<MTU>; N_TX],
+    inner: MaybeUninit<StateInner<'static, MTU>>,
+}
+
+impl<const MTU: usize, const N_RX: usize, const N_TX: usize> State<MTU, N_RX, N_TX> {
+    /// Create a new channel state.
+    pub const fn new() -> Self {
+        Self {
+            rx: [const { PacketBuf::new() }; N_RX],
+            tx: [const { PacketBuf::new() }; N_TX],
+            inner: MaybeUninit::uninit(),
+        }
+    }
+}
+
+struct StateInner<'d, const MTU: usize> {
+    rx: zerocopy_channel::Channel<'d, NoopRawMutex, PacketBuf<MTU>>,
+    tx: zerocopy_channel::Channel<'d, NoopRawMutex, PacketBuf<MTU>>,
+    shared: Mutex<NoopRawMutex, RefCell<Shared>>,
+}
+
+struct Shared {
+    link_state: LinkState,
+    waker: WakerRegistration,
+    hardware_address: driver::HardwareAddress,
+}
+
+/// Channel runner.
+///
+/// Holds the shared state and the lower end of channels for inbound and outbound packets.
+pub struct Runner<'d, const MTU: usize> {
+    tx_chan: zerocopy_channel::Receiver<'d, NoopRawMutex, PacketBuf<MTU>>,
+    rx_chan: zerocopy_channel::Sender<'d, NoopRawMutex, PacketBuf<MTU>>,
+    shared: &'d Mutex<NoopRawMutex, RefCell<Shared>>,
+}
+
+/// State runner.
+///
+/// Holds the shared state of the channel such as link state.
+#[derive(Clone, Copy)]
+pub struct StateRunner<'d> {
+    shared: &'d Mutex<NoopRawMutex, RefCell<Shared>>,
+}
+
+/// RX runner.
+///
+/// Holds the lower end of the channel for passing inbound packets up the stack.
+pub struct RxRunner<'d, const MTU: usize> {
+    rx_chan: zerocopy_channel::Sender<'d, NoopRawMutex, PacketBuf<MTU>>,
+}
+
+/// TX runner.
+///
+/// Holds the lower end of the channel for passing outbound packets down the stack.
+pub struct TxRunner<'d, const MTU: usize> {
+    tx_chan: zerocopy_channel::Receiver<'d, NoopRawMutex, PacketBuf<MTU>>,
+}
+
+impl<'d, const MTU: usize> Runner<'d, MTU> {
+    /// Split the runner into separate runners for controlling state, rx and tx.
+    pub fn split(self) -> (StateRunner<'d>, RxRunner<'d, MTU>, TxRunner<'d, MTU>) {
+        (
+            StateRunner { shared: self.shared },
+            RxRunner { rx_chan: self.rx_chan },
+            TxRunner { tx_chan: self.tx_chan },
+        )
+    }
+
+    /// Split the runner into separate runners for controlling state, rx and tx borrowing the underlying state.
+    pub fn borrow_split(&mut self) -> (StateRunner<'_>, RxRunner<'_, MTU>, TxRunner<'_, MTU>) {
+        (
+            StateRunner { shared: self.shared },
+            RxRunner {
+                rx_chan: self.rx_chan.borrow(),
+            },
+            TxRunner {
+                tx_chan: self.tx_chan.borrow(),
+            },
+        )
+    }
+
+    /// Create a state runner sharing the state channel.
+    pub fn state_runner(&self) -> StateRunner<'d> {
+        StateRunner { shared: self.shared }
+    }
+
+    /// Set the link state.
+    pub fn set_link_state(&mut self, state: LinkState) {
+        self.shared.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            s.link_state = state;
+            s.waker.wake();
+        });
+    }
+
+    /// Set the hardware address.
+    pub fn set_hardware_address(&mut self, address: driver::HardwareAddress) {
+        self.shared.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            s.hardware_address = address;
+            s.waker.wake();
+        });
+    }
+
+    /// Wait until there is space for more inbound packets and return a slice they can be copied into.
+    pub async fn rx_buf(&mut self) -> &mut [u8] {
+        let p = self.rx_chan.send().await;
+        &mut p.buf
+    }
+
+    /// Check if there is space for more inbound packets right now.
+    pub fn try_rx_buf(&mut self) -> Option<&mut [u8]> {
+        let p = self.rx_chan.try_send()?;
+        Some(&mut p.buf)
+    }
+
+    /// Polling the inbound channel if there is space for packets.
+    pub fn poll_rx_buf(&mut self, cx: &mut Context) -> Poll<&mut [u8]> {
+        match self.rx_chan.poll_send(cx) {
+            Poll::Ready(p) => Poll::Ready(&mut p.buf),
+            Poll::Pending => Poll::Pending,
+        }
+    }
+
+    /// Mark packet of len bytes as pushed to the inbound channel.
+    pub fn rx_done(&mut self, len: usize) {
+        let p = self.rx_chan.try_send().unwrap();
+        p.len = len;
+        self.rx_chan.send_done();
+    }
+
+    /// Wait until there is space for more outbound packets and return a slice they can be copied into.
+    pub async fn tx_buf(&mut self) -> &mut [u8] {
+        let p = self.tx_chan.receive().await;
+        &mut p.buf[..p.len]
+    }
+
+    /// Check if there is space for more outbound packets right now.
+    pub fn try_tx_buf(&mut self) -> Option<&mut [u8]> {
+        let p = self.tx_chan.try_receive()?;
+        Some(&mut p.buf[..p.len])
+    }
+
+    /// Polling the outbound channel if there is space for packets.
+    pub fn poll_tx_buf(&mut self, cx: &mut Context) -> Poll<&mut [u8]> {
+        match self.tx_chan.poll_receive(cx) {
+            Poll::Ready(p) => Poll::Ready(&mut p.buf[..p.len]),
+            Poll::Pending => Poll::Pending,
+        }
+    }
+
+    /// Mark outbound packet as copied.
+    pub fn tx_done(&mut self) {
+        self.tx_chan.receive_done();
+    }
+}
+
+impl<'d> StateRunner<'d> {
+    /// Set link state.
+    pub fn set_link_state(&self, state: LinkState) {
+        self.shared.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            s.link_state = state;
+            s.waker.wake();
+        });
+    }
+
+    /// Set the hardware address.
+    pub fn set_hardware_address(&self, address: driver::HardwareAddress) {
+        self.shared.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            s.hardware_address = address;
+            s.waker.wake();
+        });
+    }
+}
+
+impl<'d, const MTU: usize> RxRunner<'d, MTU> {
+    /// Wait until there is space for more inbound packets and return a slice they can be copied into.
+    pub async fn rx_buf(&mut self) -> &mut [u8] {
+        let p = self.rx_chan.send().await;
+        &mut p.buf
+    }
+
+    /// Check if there is space for more inbound packets right now.
+    pub fn try_rx_buf(&mut self) -> Option<&mut [u8]> {
+        let p = self.rx_chan.try_send()?;
+        Some(&mut p.buf)
+    }
+
+    /// Polling the inbound channel if there is space for packets.
+    pub fn poll_rx_buf(&mut self, cx: &mut Context) -> Poll<&mut [u8]> {
+        match self.rx_chan.poll_send(cx) {
+            Poll::Ready(p) => Poll::Ready(&mut p.buf),
+            Poll::Pending => Poll::Pending,
+        }
+    }
+
+    /// Mark packet of len bytes as pushed to the inbound channel.
+    pub fn rx_done(&mut self, len: usize) {
+        let p = self.rx_chan.try_send().unwrap();
+        p.len = len;
+        self.rx_chan.send_done();
+    }
+}
+
+impl<'d, const MTU: usize> TxRunner<'d, MTU> {
+    /// Wait until there is space for more outbound packets and return a slice they can be copied into.
+    pub async fn tx_buf(&mut self) -> &mut [u8] {
+        let p = self.tx_chan.receive().await;
+        &mut p.buf[..p.len]
+    }
+
+    /// Check if there is space for more outbound packets right now.
+    pub fn try_tx_buf(&mut self) -> Option<&mut [u8]> {
+        let p = self.tx_chan.try_receive()?;
+        Some(&mut p.buf[..p.len])
+    }
+
+    /// Polling the outbound channel if there is space for packets.
+    pub fn poll_tx_buf(&mut self, cx: &mut Context) -> Poll<&mut [u8]> {
+        match self.tx_chan.poll_receive(cx) {
+            Poll::Ready(p) => Poll::Ready(&mut p.buf[..p.len]),
+            Poll::Pending => Poll::Pending,
+        }
+    }
+
+    /// Mark outbound packet as copied.
+    pub fn tx_done(&mut self) {
+        self.tx_chan.receive_done();
+    }
+}
+
+/// Create a channel.
+///
+/// Returns a pair of handles for interfacing with the peripheral and the networking stack.
+///
+/// The runner is interfacing with the peripheral at the lower part of the stack.
+/// The device is interfacing with the networking stack on the layer above.
+pub fn new<'d, const MTU: usize, const N_RX: usize, const N_TX: usize>(
+    state: &'d mut State<MTU, N_RX, N_TX>,
+    hardware_address: driver::HardwareAddress,
+) -> (Runner<'d, MTU>, Device<'d, MTU>) {
+    let mut caps = Capabilities::default();
+    caps.max_transmission_unit = MTU;
+
+    // safety: this is a self-referential struct, however:
+    // - it can't move while the `'d` borrow is active.
+    // - when the borrow ends, the dangling references inside the MaybeUninit will never be used again.
+    let state_uninit: *mut MaybeUninit<StateInner<'d, MTU>> =
+        (&mut state.inner as *mut MaybeUninit<StateInner<'static, MTU>>).cast();
+    let state = unsafe { &mut *state_uninit }.write(StateInner {
+        rx: zerocopy_channel::Channel::new(&mut state.rx[..]),
+        tx: zerocopy_channel::Channel::new(&mut state.tx[..]),
+        shared: Mutex::new(RefCell::new(Shared {
+            link_state: LinkState::Down,
+            hardware_address,
+            waker: WakerRegistration::new(),
+        })),
+    });
+
+    let (rx_sender, rx_receiver) = state.rx.split();
+    let (tx_sender, tx_receiver) = state.tx.split();
+
+    (
+        Runner {
+            tx_chan: tx_receiver,
+            rx_chan: rx_sender,
+            shared: &state.shared,
+        },
+        Device {
+            caps,
+            shared: &state.shared,
+            rx: rx_receiver,
+            tx: tx_sender,
+        },
+    )
+}
+
+/// Represents a packet of size MTU.
+pub struct PacketBuf<const MTU: usize> {
+    len: usize,
+    buf: [u8; MTU],
+}
+
+impl<const MTU: usize> PacketBuf<MTU> {
+    /// Create a new packet buffer.
+    pub const fn new() -> Self {
+        Self { len: 0, buf: [0; MTU] }
+    }
+}
+
+/// Channel device.
+///
+/// Holds the shared state and upper end of channels for inbound and outbound packets.
+pub struct Device<'d, const MTU: usize> {
+    rx: zerocopy_channel::Receiver<'d, NoopRawMutex, PacketBuf<MTU>>,
+    tx: zerocopy_channel::Sender<'d, NoopRawMutex, PacketBuf<MTU>>,
+    shared: &'d Mutex<NoopRawMutex, RefCell<Shared>>,
+    caps: Capabilities,
+}
+
+impl<'d, const MTU: usize> embassy_net_driver::Driver for Device<'d, MTU> {
+    type RxToken<'a>
+        = RxToken<'a, MTU>
+    where
+        Self: 'a;
+    type TxToken<'a>
+        = TxToken<'a, MTU>
+    where
+        Self: 'a;
+
+    fn receive(&mut self, cx: &mut Context) -> Option<(Self::RxToken<'_>, Self::TxToken<'_>)> {
+        if self.rx.poll_receive(cx).is_ready() && self.tx.poll_send(cx).is_ready() {
+            Some((RxToken { rx: self.rx.borrow() }, TxToken { tx: self.tx.borrow() }))
+        } else {
+            None
+        }
+    }
+
+    /// Construct a transmit token.
+    fn transmit(&mut self, cx: &mut Context) -> Option<Self::TxToken<'_>> {
+        if self.tx.poll_send(cx).is_ready() {
+            Some(TxToken { tx: self.tx.borrow() })
+        } else {
+            None
+        }
+    }
+
+    /// Get a description of device capabilities.
+    fn capabilities(&self) -> Capabilities {
+        self.caps.clone()
+    }
+
+    fn hardware_address(&self) -> driver::HardwareAddress {
+        self.shared.lock(|s| s.borrow().hardware_address)
+    }
+
+    fn link_state(&mut self, cx: &mut Context) -> LinkState {
+        self.shared.lock(|s| {
+            let s = &mut *s.borrow_mut();
+            s.waker.register(cx.waker());
+            s.link_state
+        })
+    }
+}
+
+/// A rx token.
+///
+/// Holds inbound receive channel and interfaces with embassy-net-driver.
+pub struct RxToken<'a, const MTU: usize> {
+    rx: zerocopy_channel::Receiver<'a, NoopRawMutex, PacketBuf<MTU>>,
+}
+
+impl<'a, const MTU: usize> embassy_net_driver::RxToken for RxToken<'a, MTU> {
+    fn consume<R, F>(mut self, f: F) -> R
+    where
+        F: FnOnce(&mut [u8]) -> R,
+    {
+        // NOTE(unwrap): we checked the queue wasn't full when creating the token.
+        let pkt = unwrap!(self.rx.try_receive());
+        let r = f(&mut pkt.buf[..pkt.len]);
+        self.rx.receive_done();
+        r
+    }
+}
+
+/// A tx token.
+///
+/// Holds outbound transmit channel and interfaces with embassy-net-driver.
+pub struct TxToken<'a, const MTU: usize> {
+    tx: zerocopy_channel::Sender<'a, NoopRawMutex, PacketBuf<MTU>>,
+}
+
+impl<'a, const MTU: usize> embassy_net_driver::TxToken for TxToken<'a, MTU> {
+    fn consume<R, F>(mut self, len: usize, f: F) -> R
+    where
+        F: FnOnce(&mut [u8]) -> R,
+    {
+        // NOTE(unwrap): we checked the queue wasn't full when creating the token.
+        let pkt = unwrap!(self.tx.try_send());
+        let r = f(&mut pkt.buf[..len]);
+        pkt.len = len;
+        self.tx.send_done();
+        r
+    }
+}