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-nrf/src/radio/ble.rs

@@ -0,0 +1,412 @@
+//! Radio driver implementation focused on Bluetooth Low-Energy transmission.
+
+use core::future::poll_fn;
+use core::sync::atomic::{compiler_fence, Ordering};
+use core::task::Poll;
+
+use embassy_hal_internal::drop::OnDrop;
+use embassy_hal_internal::{into_ref, PeripheralRef};
+pub use pac::radio::mode::MODE_A as Mode;
+#[cfg(not(feature = "nrf51"))]
+use pac::radio::pcnf0::PLEN_A as PreambleLength;
+
+use crate::interrupt::typelevel::Interrupt;
+use crate::radio::*;
+pub use crate::radio::{Error, TxPower};
+use crate::util::slice_in_ram_or;
+
+/// Radio driver.
+pub struct Radio<'d, T: Instance> {
+    _p: PeripheralRef<'d, T>,
+}
+
+impl<'d, T: Instance> Radio<'d, T> {
+    /// Create a new radio driver.
+    pub fn new(
+        radio: impl Peripheral<P = T> + 'd,
+        _irq: impl interrupt::typelevel::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
+    ) -> Self {
+        into_ref!(radio);
+
+        let r = T::regs();
+
+        r.pcnf1.write(|w| unsafe {
+            // It is 0 bytes long in a standard BLE packet
+            w.statlen()
+                .bits(0)
+                // MaxLen configures the maximum packet payload plus add-on size in
+                // number of bytes that can be transmitted or received by the RADIO. This feature can be used to ensure
+                // that the RADIO does not overwrite, or read beyond, the RAM assigned to the packet payload. This means
+                // that if the packet payload length defined by PCNF1.STATLEN and the LENGTH field in the packet specifies a
+                // packet larger than MAXLEN, the payload will be truncated at MAXLEN
+                //
+                // To simplify the implementation, It is setted as the maximum value
+                // and the length of the packet is controlled only by the LENGTH field in the packet
+                .maxlen()
+                .bits(255)
+                // Configure the length of the address field in the packet
+                // The prefix after the address fields is always appended, so is always 1 byte less than the size of the address
+                // The base address is truncated from the least significant byte if the BALEN is less than 4
+                //
+                // BLE address is always 4 bytes long
+                .balen()
+                .bits(3) // 3 bytes base address (+ 1 prefix);
+                // Configure the endianess
+                // For BLE is always little endian (LSB first)
+                .endian()
+                .little()
+                // Data whitening is used to avoid long sequences of zeros or
+                // ones, e.g., 0b0000000 or 0b1111111, in the data bit stream.
+                // The whitener and de-whitener are defined the same way,
+                // using a 7-bit linear feedback shift register with the
+                // polynomial x7 + x4 + 1.
+                //
+                // In BLE Whitening shall be applied on the PDU and CRC of all
+                // Link Layer packets and is performed after the CRC generation
+                // in the transmitter. No other parts of the packets are whitened.
+                // De-whitening is performed before the CRC checking in the receiver
+                // Before whitening or de-whitening, the shift register should be
+                // initialized based on the channel index.
+                .whiteen()
+                .set_bit()
+        });
+
+        // Configure CRC
+        r.crccnf.write(|w| {
+            // In BLE the CRC shall be calculated on the PDU of all Link Layer
+            // packets (even if the packet is encrypted).
+            // It skips the address field
+            w.skipaddr()
+                .skip()
+                // In BLE  24-bit CRC = 3 bytes
+                .len()
+                .three()
+        });
+
+        // Ch map between 2400 MHZ .. 2500 MHz
+        // All modes use this range
+        #[cfg(not(feature = "nrf51"))]
+        r.frequency.write(|w| w.map().default());
+
+        // Configure shortcuts to simplify and speed up sending and receiving packets.
+        r.shorts.write(|w| {
+            // start transmission/recv immediately after ramp-up
+            // disable radio when transmission/recv is done
+            w.ready_start().enabled().end_disable().enabled()
+        });
+
+        // Enable NVIC interrupt
+        T::Interrupt::unpend();
+        unsafe { T::Interrupt::enable() };
+
+        Self { _p: radio }
+    }
+
+    fn state(&self) -> RadioState {
+        super::state(T::regs())
+    }
+
+    /// Set the radio mode
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_mode(&mut self, mode: Mode) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+        r.mode.write(|w| w.mode().variant(mode));
+
+        #[cfg(not(feature = "nrf51"))]
+        r.pcnf0.write(|w| {
+            w.plen().variant(match mode {
+                Mode::BLE_1MBIT => PreambleLength::_8BIT,
+                Mode::BLE_2MBIT => PreambleLength::_16BIT,
+                #[cfg(any(
+                    feature = "nrf52811",
+                    feature = "nrf52820",
+                    feature = "nrf52833",
+                    feature = "nrf52840",
+                    feature = "_nrf5340-net"
+                ))]
+                Mode::BLE_LR125KBIT | Mode::BLE_LR500KBIT => PreambleLength::LONG_RANGE,
+                _ => unimplemented!(),
+            })
+        });
+    }
+
+    /// Set the header size changing the S1's len field
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_header_expansion(&mut self, use_s1_field: bool) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+
+        // s1 len in bits
+        let s1len: u8 = match use_s1_field {
+            false => 0,
+            true => 8,
+        };
+
+        r.pcnf0.write(|w| unsafe {
+            w
+                // Configure S0 to 1 byte length, this will represent the Data/Adv header flags
+                .s0len()
+                .set_bit()
+                // Configure the length (in bits) field to 1 byte length, this will represent the length of the payload
+                // and also be used to know how many bytes to read/write from/to the buffer
+                .lflen()
+                .bits(8)
+                // Configure the lengh (in bits) of bits in the S1 field. It could be used to represent the CTEInfo for data packages in BLE.
+                .s1len()
+                .bits(s1len)
+        });
+    }
+
+    /// Set initial data whitening value
+    /// Data whitening is used to avoid long sequences of zeros or ones, e.g., 0b0000000 or 0b1111111, in the data bit stream
+    /// On BLE the initial value is the channel index | 0x40
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_whitening_init(&mut self, whitening_init: u8) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+
+        r.datawhiteiv.write(|w| unsafe { w.datawhiteiv().bits(whitening_init) });
+    }
+
+    /// Set the central frequency to be used
+    /// It should be in the range 2400..2500
+    ///
+    /// [The radio must be disabled before calling this function](https://devzone.nordicsemi.com/f/nordic-q-a/15829/radio-frequency-change)
+    pub fn set_frequency(&mut self, frequency: u32) {
+        assert!(self.state() == RadioState::DISABLED);
+        assert!((2400..=2500).contains(&frequency));
+
+        let r = T::regs();
+
+        r.frequency
+            .write(|w| unsafe { w.frequency().bits((frequency - 2400) as u8) });
+    }
+
+    /// Set the acess address
+    /// This address is always constants for advertising
+    /// And a random value generate on each connection
+    /// It is used to filter the packages
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_access_address(&mut self, access_address: u32) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+
+        // Configure logical address
+        // The byte ordering on air is always least significant byte first for the address
+        // So for the address 0xAA_BB_CC_DD, the address on air will be DD CC BB AA
+        // The package order is BASE, PREFIX so BASE=0xBB_CC_DD and PREFIX=0xAA
+        r.prefix0
+            .write(|w| unsafe { w.ap0().bits((access_address >> 24) as u8) });
+
+        // The base address is truncated from the least significant byte (because the BALEN is less than 4)
+        // So it shifts the address to the right
+        r.base0.write(|w| unsafe { w.bits(access_address << 8) });
+
+        // Don't match tx address
+        r.txaddress.write(|w| unsafe { w.txaddress().bits(0) });
+
+        // Match on logical address
+        // This config only filter the packets by the address,
+        // so only packages send to the previous address
+        // will finish the reception (TODO: check the explanation)
+        r.rxaddresses.write(|w| {
+            w.addr0()
+                .enabled()
+                .addr1()
+                .enabled()
+                .addr2()
+                .enabled()
+                .addr3()
+                .enabled()
+                .addr4()
+                .enabled()
+        });
+    }
+
+    /// Set the CRC polynomial
+    /// It only uses the 24 least significant bits
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_crc_poly(&mut self, crc_poly: u32) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+
+        r.crcpoly.write(|w| unsafe {
+            // Configure the CRC polynomial
+            // Each term in the CRC polynomial is mapped to a bit in this
+            // register which index corresponds to the term's exponent.
+            // The least significant term/bit is hard-wired internally to
+            // 1, and bit number 0 of the register content is ignored by
+            // the hardware. The following example is for an 8 bit CRC
+            // polynomial: x8 + x7 + x3 + x2 + 1 = 1 1000 1101 .
+            w.crcpoly().bits(crc_poly & 0xFFFFFF)
+        });
+    }
+
+    /// Set the CRC init value
+    /// It only uses the 24 least significant bits
+    /// The CRC initial value varies depending of the PDU type
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_crc_init(&mut self, crc_init: u32) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+
+        r.crcinit.write(|w| unsafe { w.crcinit().bits(crc_init & 0xFFFFFF) });
+    }
+
+    /// Set the radio tx power
+    ///
+    /// The radio must be disabled before calling this function
+    pub fn set_tx_power(&mut self, tx_power: TxPower) {
+        assert!(self.state() == RadioState::DISABLED);
+
+        let r = T::regs();
+
+        r.txpower.write(|w| w.txpower().variant(tx_power));
+    }
+
+    /// Set buffer to read/write
+    ///
+    /// This method is unsound. You should guarantee that the buffer will live
+    /// for the life time of the transmission or if the buffer will be modified.
+    /// Also if the buffer is smaller than the packet length, the radio will
+    /// read/write memory out of the buffer bounds.
+    fn set_buffer(&mut self, buffer: &[u8]) -> Result<(), Error> {
+        slice_in_ram_or(buffer, Error::BufferNotInRAM)?;
+
+        let r = T::regs();
+
+        // Here it consider that the length of the packet is
+        // correctly set in the buffer, otherwise it will send
+        // unowned regions of memory
+        let ptr = buffer.as_ptr();
+
+        // Configure the payload
+        r.packetptr.write(|w| unsafe { w.bits(ptr as u32) });
+
+        Ok(())
+    }
+
+    /// Send packet
+    /// If the length byte in the package is greater than the buffer length
+    /// the radio will read memory out of the buffer bounds
+    pub async fn transmit(&mut self, buffer: &[u8]) -> Result<(), Error> {
+        self.set_buffer(buffer)?;
+
+        let r = T::regs();
+        self.trigger_and_wait_end(move || {
+            // Initialize the transmission
+            // trace!("txen");
+
+            r.tasks_txen.write(|w| unsafe { w.bits(1) });
+        })
+        .await;
+
+        Ok(())
+    }
+
+    /// Receive packet
+    /// If the length byte in the received package is greater than the buffer length
+    /// the radio will write memory out of the buffer bounds
+    pub async fn receive(&mut self, buffer: &mut [u8]) -> Result<(), Error> {
+        self.set_buffer(buffer)?;
+
+        let r = T::regs();
+        self.trigger_and_wait_end(move || {
+            // Initialize the transmission
+            // trace!("rxen");
+            r.tasks_rxen.write(|w| unsafe { w.bits(1) });
+        })
+        .await;
+
+        Ok(())
+    }
+
+    async fn trigger_and_wait_end(&mut self, trigger: impl FnOnce()) {
+        let r = T::regs();
+        let s = T::state();
+
+        // If the Future is dropped before the end of the transmission
+        // it disable the interrupt and stop the transmission
+        // to keep the state consistent
+        let drop = OnDrop::new(|| {
+            trace!("radio drop: stopping");
+
+            r.intenclr.write(|w| w.end().clear());
+
+            r.tasks_stop.write(|w| unsafe { w.bits(1) });
+
+            r.events_end.reset();
+
+            trace!("radio drop: stopped");
+        });
+
+        // trace!("radio:enable interrupt");
+        // Clear some remnant side-effects (TODO: check if this is necessary)
+        r.events_end.reset();
+
+        // Enable interrupt
+        r.intenset.write(|w| w.end().set());
+
+        compiler_fence(Ordering::SeqCst);
+
+        // Trigger the transmission
+        trigger();
+
+        // On poll check if interrupt happen
+        poll_fn(|cx| {
+            s.event_waker.register(cx.waker());
+            if r.events_end.read().bits() == 1 {
+                // trace!("radio:end");
+                return core::task::Poll::Ready(());
+            }
+            Poll::Pending
+        })
+        .await;
+
+        compiler_fence(Ordering::SeqCst);
+        r.events_end.reset(); // ACK
+
+        // Everthing ends fine, so it disable the drop
+        drop.defuse();
+    }
+
+    /// Disable the radio
+    fn disable(&mut self) {
+        let r = T::regs();
+
+        compiler_fence(Ordering::SeqCst);
+        // If it is already disabled, do nothing
+        if self.state() != RadioState::DISABLED {
+            trace!("radio:disable");
+            // Trigger the disable task
+            r.tasks_disable.write(|w| unsafe { w.bits(1) });
+
+            // Wait until the radio is disabled
+            while r.events_disabled.read().bits() == 0 {}
+
+            compiler_fence(Ordering::SeqCst);
+
+            // Acknowledge it
+            r.events_disabled.reset();
+        }
+    }
+}
+
+impl<'d, T: Instance> Drop for Radio<'d, T> {
+    fn drop(&mut self) {
+        self.disable();
+    }
+}

vendor/embassy-nrf/src/radio/ieee802154.rs

@@ -0,0 +1,546 @@
+//! IEEE 802.15.4 radio driver
+
+use core::sync::atomic::{compiler_fence, Ordering};
+use core::task::Poll;
+
+use embassy_hal_internal::drop::OnDrop;
+use embassy_hal_internal::{into_ref, PeripheralRef};
+
+use super::{state, Error, Instance, InterruptHandler, RadioState, TxPower};
+use crate::interrupt::typelevel::Interrupt;
+use crate::interrupt::{self};
+use crate::Peripheral;
+
+/// Default (IEEE compliant) Start of Frame Delimiter
+pub const DEFAULT_SFD: u8 = 0xA7;
+
+// TODO expose the other variants in `pac::CCAMODE_A`
+/// Clear Channel Assessment method
+pub enum Cca {
+    /// Carrier sense
+    CarrierSense,
+    /// Energy Detection / Energy Above Threshold
+    EnergyDetection {
+        /// Energy measurements above this value mean that the channel is assumed to be busy.
+        /// Note the measurement range is 0..0xFF - where 0 means that the received power was
+        /// less than 10 dB above the selected receiver sensitivity. This value is not given in dBm,
+        /// but can be converted. See the nrf52840 Product Specification Section 6.20.12.4
+        /// for details.
+        ed_threshold: u8,
+    },
+}
+
+/// IEEE 802.15.4 radio driver.
+pub struct Radio<'d, T: Instance> {
+    _p: PeripheralRef<'d, T>,
+    needs_enable: bool,
+}
+
+impl<'d, T: Instance> Radio<'d, T> {
+    /// Create a new IEEE 802.15.4 radio driver.
+    pub fn new(
+        radio: impl Peripheral<P = T> + 'd,
+        _irq: impl interrupt::typelevel::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
+    ) -> Self {
+        into_ref!(radio);
+
+        let r = T::regs();
+
+        // Disable and enable to reset peripheral
+        r.power.write(|w| w.power().disabled());
+        r.power.write(|w| w.power().enabled());
+
+        // Enable 802.15.4 mode
+        r.mode.write(|w| w.mode().ieee802154_250kbit());
+        // Configure CRC skip address
+        r.crccnf.write(|w| w.len().two().skipaddr().ieee802154());
+        unsafe {
+            // Configure CRC polynomial and init
+            r.crcpoly.write(|w| w.crcpoly().bits(0x0001_1021));
+            r.crcinit.write(|w| w.crcinit().bits(0));
+            r.pcnf0.write(|w| {
+                // 8-bit on air length
+                w.lflen()
+                    .bits(8)
+                    // Zero bytes S0 field length
+                    .s0len()
+                    .clear_bit()
+                    // Zero bytes S1 field length
+                    .s1len()
+                    .bits(0)
+                    // Do not include S1 field in RAM if S1 length > 0
+                    .s1incl()
+                    .clear_bit()
+                    // Zero code Indicator length
+                    .cilen()
+                    .bits(0)
+                    // 32-bit zero preamble
+                    .plen()
+                    ._32bit_zero()
+                    // Include CRC in length
+                    .crcinc()
+                    .include()
+            });
+            r.pcnf1.write(|w| {
+                // Maximum packet length
+                w.maxlen()
+                    .bits(Packet::MAX_PSDU_LEN)
+                    // Zero static length
+                    .statlen()
+                    .bits(0)
+                    // Zero base address length
+                    .balen()
+                    .bits(0)
+                    // Little-endian
+                    .endian()
+                    .clear_bit()
+                    // Disable packet whitening
+                    .whiteen()
+                    .clear_bit()
+            });
+        }
+
+        // Enable NVIC interrupt
+        T::Interrupt::unpend();
+        unsafe { T::Interrupt::enable() };
+
+        let mut radio = Self {
+            _p: radio,
+            needs_enable: false,
+        };
+
+        radio.set_sfd(DEFAULT_SFD);
+        radio.set_transmission_power(0);
+        radio.set_channel(11);
+        radio.set_cca(Cca::CarrierSense);
+
+        radio
+    }
+
+    /// Changes the radio channel
+    pub fn set_channel(&mut self, channel: u8) {
+        let r = T::regs();
+        if channel < 11 || channel > 26 {
+            panic!("Bad 802.15.4 channel");
+        }
+        let frequency_offset = (channel - 10) * 5;
+        self.needs_enable = true;
+        r.frequency
+            .write(|w| unsafe { w.frequency().bits(frequency_offset).map().default() });
+    }
+
+    /// Changes the Clear Channel Assessment method
+    pub fn set_cca(&mut self, cca: Cca) {
+        let r = T::regs();
+        self.needs_enable = true;
+        match cca {
+            Cca::CarrierSense => r.ccactrl.write(|w| w.ccamode().carrier_mode()),
+            Cca::EnergyDetection { ed_threshold } => {
+                // "[ED] is enabled by first configuring the field CCAMODE=EdMode in CCACTRL
+                // and writing the CCAEDTHRES field to a chosen value."
+                r.ccactrl
+                    .write(|w| unsafe { w.ccamode().ed_mode().ccaedthres().bits(ed_threshold) });
+            }
+        }
+    }
+
+    /// Changes the Start of Frame Delimiter (SFD)
+    pub fn set_sfd(&mut self, sfd: u8) {
+        let r = T::regs();
+        r.sfd.write(|w| unsafe { w.sfd().bits(sfd) });
+    }
+
+    /// Clear interrupts
+    pub fn clear_all_interrupts(&mut self) {
+        let r = T::regs();
+        r.intenclr.write(|w| unsafe { w.bits(0xffff_ffff) });
+    }
+
+    /// Changes the radio transmission power
+    pub fn set_transmission_power(&mut self, power: i8) {
+        let r = T::regs();
+        self.needs_enable = true;
+
+        let tx_power: TxPower = match power {
+            #[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
+            8 => TxPower::POS8D_BM,
+            #[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
+            7 => TxPower::POS7D_BM,
+            #[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
+            6 => TxPower::POS6D_BM,
+            #[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
+            5 => TxPower::POS5D_BM,
+            #[cfg(not(feature = "_nrf5340-net"))]
+            4 => TxPower::POS4D_BM,
+            #[cfg(not(feature = "_nrf5340-net"))]
+            3 => TxPower::POS3D_BM,
+            #[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
+            2 => TxPower::POS2D_BM,
+            0 => TxPower::_0D_BM,
+            #[cfg(feature = "_nrf5340-net")]
+            -1 => TxPower::NEG1D_BM,
+            #[cfg(feature = "_nrf5340-net")]
+            -2 => TxPower::NEG2D_BM,
+            #[cfg(feature = "_nrf5340-net")]
+            -3 => TxPower::NEG3D_BM,
+            -4 => TxPower::NEG4D_BM,
+            #[cfg(feature = "_nrf5340-net")]
+            -5 => TxPower::NEG5D_BM,
+            #[cfg(feature = "_nrf5340-net")]
+            -6 => TxPower::NEG6D_BM,
+            #[cfg(feature = "_nrf5340-net")]
+            -7 => TxPower::NEG7D_BM,
+            -8 => TxPower::NEG8D_BM,
+            -12 => TxPower::NEG12D_BM,
+            -16 => TxPower::NEG16D_BM,
+            -20 => TxPower::NEG20D_BM,
+            -30 => TxPower::NEG30D_BM,
+            -40 => TxPower::NEG40D_BM,
+            _ => panic!("Invalid transmission power value"),
+        };
+
+        r.txpower.write(|w| w.txpower().variant(tx_power));
+    }
+
+    /// Waits until the radio state matches the given `state`
+    fn wait_for_radio_state(&self, state: RadioState) {
+        while self.state() != state {}
+    }
+
+    /// Get the current radio state
+    fn state(&self) -> RadioState {
+        state(T::regs())
+    }
+
+    /// Moves the radio from any state to the DISABLED state
+    fn disable(&mut self) {
+        let r = T::regs();
+        // See figure 110 in nRF52840-PS
+        loop {
+            match self.state() {
+                RadioState::DISABLED => return,
+                // idle or ramping up
+                RadioState::RX_RU | RadioState::RX_IDLE | RadioState::TX_RU | RadioState::TX_IDLE => {
+                    r.tasks_disable.write(|w| w.tasks_disable().set_bit());
+                    self.wait_for_radio_state(RadioState::DISABLED);
+                    return;
+                }
+                // ramping down
+                RadioState::RX_DISABLE | RadioState::TX_DISABLE => {
+                    self.wait_for_radio_state(RadioState::DISABLED);
+                    return;
+                }
+                // cancel ongoing transfer or ongoing CCA
+                RadioState::RX => {
+                    r.tasks_ccastop.write(|w| w.tasks_ccastop().set_bit());
+                    r.tasks_stop.write(|w| w.tasks_stop().set_bit());
+                    self.wait_for_radio_state(RadioState::RX_IDLE);
+                }
+                RadioState::TX => {
+                    r.tasks_stop.write(|w| w.tasks_stop().set_bit());
+                    self.wait_for_radio_state(RadioState::TX_IDLE);
+                }
+            }
+        }
+    }
+
+    fn set_buffer(&mut self, buffer: &[u8]) {
+        let r = T::regs();
+        r.packetptr.write(|w| unsafe { w.bits(buffer.as_ptr() as u32) });
+    }
+
+    /// Moves the radio to the RXIDLE state
+    fn receive_prepare(&mut self) {
+        // clear related events
+        T::regs().events_ccabusy.reset();
+        T::regs().events_phyend.reset();
+        // NOTE to avoid errata 204 (see rev1 v1.4) we do TX_IDLE -> DISABLED -> RX_IDLE
+        let disable = match self.state() {
+            RadioState::DISABLED => false,
+            RadioState::RX_IDLE => self.needs_enable,
+            _ => true,
+        };
+        if disable {
+            self.disable();
+        }
+        self.needs_enable = false;
+    }
+
+    /// Prepare radio for receiving a packet
+    fn receive_start(&mut self, packet: &mut Packet) {
+        // NOTE we do NOT check the address of `packet` because the mutable reference ensures it's
+        // allocated in RAM
+        let r = T::regs();
+
+        self.receive_prepare();
+
+        // Configure shortcuts
+        //
+        // The radio goes through following states when receiving a 802.15.4 packet
+        //
+        // enable RX → ramp up RX → RX idle → Receive → end (PHYEND)
+        r.shorts.write(|w| w.rxready_start().enabled());
+
+        // set up RX buffer
+        self.set_buffer(packet.buffer.as_mut());
+
+        // start transfer
+        dma_start_fence();
+
+        match self.state() {
+            // Re-start receiver
+            RadioState::RX_IDLE => r.tasks_start.write(|w| w.tasks_start().set_bit()),
+            // Enable receiver
+            _ => r.tasks_rxen.write(|w| w.tasks_rxen().set_bit()),
+        }
+    }
+
+    /// Cancel receiving packet
+    fn receive_cancel() {
+        let r = T::regs();
+        r.shorts.reset();
+        r.tasks_stop.write(|w| w.tasks_stop().set_bit());
+        loop {
+            match state(r) {
+                RadioState::DISABLED | RadioState::RX_IDLE => break,
+                _ => (),
+            }
+        }
+        // DMA transfer may have been in progress so synchronize with its memory operations
+        dma_end_fence();
+    }
+
+    /// Receives one radio packet and copies its contents into the given `packet` buffer
+    ///
+    /// This methods returns the `Ok` variant if the CRC included the packet was successfully
+    /// validated by the hardware; otherwise it returns the `Err` variant. In either case, `packet`
+    /// will be updated with the received packet's data
+    pub async fn receive(&mut self, packet: &mut Packet) -> Result<(), Error> {
+        let s = T::state();
+        let r = T::regs();
+
+        // Start the read
+        self.receive_start(packet);
+
+        let dropper = OnDrop::new(|| Self::receive_cancel());
+
+        self.clear_all_interrupts();
+        // wait until we have received something
+        core::future::poll_fn(|cx| {
+            s.event_waker.register(cx.waker());
+
+            if r.events_phyend.read().events_phyend().bit_is_set() {
+                r.events_phyend.reset();
+                trace!("RX done poll");
+                return Poll::Ready(());
+            } else {
+                r.intenset.write(|w| w.phyend().set());
+            };
+
+            Poll::Pending
+        })
+        .await;
+
+        dma_end_fence();
+        dropper.defuse();
+
+        let crc = r.rxcrc.read().rxcrc().bits() as u16;
+        if r.crcstatus.read().crcstatus().bit_is_set() {
+            Ok(())
+        } else {
+            Err(Error::CrcFailed(crc))
+        }
+    }
+
+    /// Tries to send the given `packet`
+    ///
+    /// This method performs Clear Channel Assessment (CCA) first and sends the `packet` only if the
+    /// channel is observed to be *clear* (no transmission is currently ongoing), otherwise no
+    /// packet is transmitted and the `Err` variant is returned
+    ///
+    /// NOTE this method will *not* modify the `packet` argument. The mutable reference is used to
+    /// ensure the `packet` buffer is allocated in RAM, which is required by the RADIO peripheral
+    // NOTE we do NOT check the address of `packet` because the mutable reference ensures it's
+    // allocated in RAM
+    pub async fn try_send(&mut self, packet: &mut Packet) -> Result<(), Error> {
+        let s = T::state();
+        let r = T::regs();
+
+        // enable radio to perform cca
+        self.receive_prepare();
+
+        /// transmit result
+        #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+        #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+        pub enum TransmitResult {
+            /// Success
+            Success,
+            /// Clear channel assessment reported channel in use
+            ChannelInUse,
+        }
+
+        // Configure shortcuts
+        //
+        // The radio goes through following states when sending a 802.15.4 packet
+        //
+        // enable RX → ramp up RX → clear channel assessment (CCA) → CCA result
+        // CCA idle → enable TX → start TX → TX → end (PHYEND) → disabled
+        //
+        // CCA might end up in the event CCABUSY in which there will be no transmission
+        r.shorts.write(|w| {
+            w.rxready_ccastart()
+                .enabled()
+                .ccaidle_txen()
+                .enabled()
+                .txready_start()
+                .enabled()
+                .ccabusy_disable()
+                .enabled()
+                .phyend_disable()
+                .enabled()
+        });
+
+        // Set transmission buffer
+        self.set_buffer(packet.buffer.as_mut());
+
+        // the DMA transfer will start at some point after the following write operation so
+        // we place the compiler fence here
+        dma_start_fence();
+        // start CCA. In case the channel is clear, the data at packetptr will be sent automatically
+
+        match self.state() {
+            // Re-start receiver
+            RadioState::RX_IDLE => r.tasks_ccastart.write(|w| w.tasks_ccastart().set_bit()),
+            // Enable receiver
+            _ => r.tasks_rxen.write(|w| w.tasks_rxen().set_bit()),
+        }
+
+        self.clear_all_interrupts();
+        let result = core::future::poll_fn(|cx| {
+            s.event_waker.register(cx.waker());
+
+            if r.events_phyend.read().events_phyend().bit_is_set() {
+                r.events_phyend.reset();
+                r.events_ccabusy.reset();
+                trace!("TX done poll");
+                return Poll::Ready(TransmitResult::Success);
+            } else if r.events_ccabusy.read().events_ccabusy().bit_is_set() {
+                r.events_ccabusy.reset();
+                trace!("TX no CCA");
+                return Poll::Ready(TransmitResult::ChannelInUse);
+            }
+
+            r.intenset.write(|w| w.phyend().set().ccabusy().set());
+
+            Poll::Pending
+        })
+        .await;
+
+        match result {
+            TransmitResult::Success => Ok(()),
+            TransmitResult::ChannelInUse => Err(Error::ChannelInUse),
+        }
+    }
+}
+
+/// An IEEE 802.15.4 packet
+///
+/// This `Packet` is a PHY layer packet. It's made up of the physical header (PHR) and the PSDU
+/// (PHY service data unit). The PSDU of this `Packet` will always include the MAC level CRC, AKA
+/// the FCS (Frame Control Sequence) -- the CRC is fully computed in hardware and automatically
+/// appended on transmission and verified on reception.
+///
+/// The API lets users modify the usable part (not the CRC) of the PSDU via the `deref` and
+/// `copy_from_slice` methods. These methods will automatically update the PHR.
+///
+/// See figure 119 in the Product Specification of the nRF52840 for more details
+pub struct Packet {
+    buffer: [u8; Self::SIZE],
+}
+
+// See figure 124 in nRF52840-PS
+impl Packet {
+    // for indexing purposes
+    const PHY_HDR: usize = 0;
+    const DATA: core::ops::RangeFrom<usize> = 1..;
+
+    /// Maximum amount of usable payload (CRC excluded) a single packet can contain, in bytes
+    pub const CAPACITY: u8 = 125;
+    const CRC: u8 = 2; // size of the CRC, which is *never* copied to / from RAM
+    const MAX_PSDU_LEN: u8 = Self::CAPACITY + Self::CRC;
+    const SIZE: usize = 1 /* PHR */ + Self::MAX_PSDU_LEN as usize;
+
+    /// Returns an empty packet (length = 0)
+    pub fn new() -> Self {
+        let mut packet = Self {
+            buffer: [0; Self::SIZE],
+        };
+        packet.set_len(0);
+        packet
+    }
+
+    /// Fills the packet payload with given `src` data
+    ///
+    /// # Panics
+    ///
+    /// This function panics if `src` is larger than `Self::CAPACITY`
+    pub fn copy_from_slice(&mut self, src: &[u8]) {
+        assert!(src.len() <= Self::CAPACITY as usize);
+        let len = src.len() as u8;
+        self.buffer[Self::DATA][..len as usize].copy_from_slice(&src[..len.into()]);
+        self.set_len(len);
+    }
+
+    /// Returns the size of this packet's payload
+    pub fn len(&self) -> u8 {
+        self.buffer[Self::PHY_HDR] - Self::CRC
+    }
+
+    /// Changes the size of the packet's payload
+    ///
+    /// # Panics
+    ///
+    /// This function panics if `len` is larger than `Self::CAPACITY`
+    pub fn set_len(&mut self, len: u8) {
+        assert!(len <= Self::CAPACITY);
+        self.buffer[Self::PHY_HDR] = len + Self::CRC;
+    }
+
+    /// Returns the LQI (Link Quality Indicator) of the received packet
+    ///
+    /// Note that the LQI is stored in the `Packet`'s internal buffer by the hardware so the value
+    /// returned by this method is only valid after a `Radio.recv` operation. Operations that
+    /// modify the `Packet`, like `copy_from_slice` or `set_len`+`deref_mut`, will overwrite the
+    /// stored LQI value.
+    ///
+    /// Also note that the hardware will *not* compute a LQI for packets smaller than 3 bytes so
+    /// this method will return an invalid value for those packets.
+    pub fn lqi(&self) -> u8 {
+        self.buffer[1 /* PHY_HDR */ + self.len() as usize /* data */]
+    }
+}
+
+impl core::ops::Deref for Packet {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        &self.buffer[Self::DATA][..self.len() as usize]
+    }
+}
+
+impl core::ops::DerefMut for Packet {
+    fn deref_mut(&mut self) -> &mut [u8] {
+        let len = self.len();
+        &mut self.buffer[Self::DATA][..len as usize]
+    }
+}
+
+/// NOTE must be followed by a volatile write operation
+fn dma_start_fence() {
+    compiler_fence(Ordering::Release);
+}
+
+/// NOTE must be preceded by a volatile read operation
+fn dma_end_fence() {
+    compiler_fence(Ordering::Acquire);
+}

vendor/embassy-nrf/src/radio/mod.rs

@@ -0,0 +1,108 @@
+//! Integrated 2.4 GHz Radio
+//!
+//! The 2.4 GHz radio transceiver is compatible with multiple radio standards
+//! such as 1Mbps, 2Mbps and Long Range Bluetooth Low Energy.
+
+#![macro_use]
+
+/// Bluetooth Low Energy Radio driver.
+pub mod ble;
+#[cfg(any(
+    feature = "nrf52811",
+    feature = "nrf52820",
+    feature = "nrf52833",
+    feature = "nrf52840",
+    feature = "_nrf5340-net"
+))]
+/// IEEE 802.15.4
+pub mod ieee802154;
+
+use core::marker::PhantomData;
+
+use embassy_sync::waitqueue::AtomicWaker;
+use pac::radio::state::STATE_A as RadioState;
+pub use pac::radio::txpower::TXPOWER_A as TxPower;
+
+use crate::{interrupt, pac, Peripheral};
+
+/// RADIO error.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[non_exhaustive]
+pub enum Error {
+    /// Buffer was too long.
+    BufferTooLong,
+    /// Buffer was too short.
+    BufferTooShort,
+    /// The buffer is not in data RAM. It's most likely in flash, and nRF's DMA cannot access flash.
+    BufferNotInRAM,
+    /// Clear channel assessment reported channel in use
+    ChannelInUse,
+    /// CRC check failed
+    CrcFailed(u16),
+}
+
+/// Interrupt handler
+pub struct InterruptHandler<T: Instance> {
+    _phantom: PhantomData<T>,
+}
+
+impl<T: Instance> interrupt::typelevel::Handler<T::Interrupt> for InterruptHandler<T> {
+    unsafe fn on_interrupt() {
+        let r = T::regs();
+        let s = T::state();
+        // clear all interrupts
+        r.intenclr.write(|w| w.bits(0xffff_ffff));
+        s.event_waker.wake();
+    }
+}
+
+pub(crate) struct State {
+    /// end packet transmission or reception
+    event_waker: AtomicWaker,
+}
+impl State {
+    pub(crate) const fn new() -> Self {
+        Self {
+            event_waker: AtomicWaker::new(),
+        }
+    }
+}
+
+pub(crate) trait SealedInstance {
+    fn regs() -> &'static crate::pac::radio::RegisterBlock;
+    fn state() -> &'static State;
+}
+
+macro_rules! impl_radio {
+    ($type:ident, $pac_type:ident, $irq:ident) => {
+        impl crate::radio::SealedInstance for peripherals::$type {
+            fn regs() -> &'static pac::radio::RegisterBlock {
+                unsafe { &*pac::$pac_type::ptr() }
+            }
+
+            fn state() -> &'static crate::radio::State {
+                static STATE: crate::radio::State = crate::radio::State::new();
+                &STATE
+            }
+        }
+        impl crate::radio::Instance for peripherals::$type {
+            type Interrupt = crate::interrupt::typelevel::$irq;
+        }
+    };
+}
+
+/// Radio peripheral instance.
+#[allow(private_bounds)]
+pub trait Instance: Peripheral<P = Self> + SealedInstance + 'static + Send {
+    /// Interrupt for this peripheral.
+    type Interrupt: interrupt::typelevel::Interrupt;
+}
+
+/// Get the state of the radio
+pub(crate) fn state(radio: &pac::radio::RegisterBlock) -> RadioState {
+    match radio.state.read().state().variant() {
+        Some(state) => state,
+        None => unreachable!(),
+    }
+}