nrf: Add NFCT driver.

Co-Authored-By: turbocool3r <turbocool3r@gmail.com>
Co-Authored-By: ferris <ferris@devdroplets.com>

embassy-nrf/src/chips/nrf52832.rs

@@ -161,6 +161,9 @@ embassy_hal_internal::peripherals! {
     EGU3,
     EGU4,
     EGU5,
+
+    // NFC
+    NFCT,
 }
 
 impl_uarte!(UARTE0, UARTE0, UARTE0);

embassy-nrf/src/chips/nrf52833.rs

@@ -181,6 +181,9 @@ embassy_hal_internal::peripherals! {
     EGU3,
     EGU4,
     EGU5,
+
+    // NFC
+    NFCT,
 }
 
 impl_usb!(USBD, USBD, USBD);

embassy-nrf/src/chips/nrf52840.rs

@@ -184,6 +184,9 @@ embassy_hal_internal::peripherals! {
     EGU3,
     EGU4,
     EGU5,
+
+    // NFC
+    NFCT,
 }
 
 impl_usb!(USBD, USBD, USBD);

embassy-nrf/src/chips/nrf5340_app.rs

@@ -176,6 +176,9 @@ embassy_hal_internal::peripherals! {
     // NVMC
     NVMC,
 
+    // NFC
+    NFCT,
+
     // UARTE, TWI & SPI
     SERIAL0,
     SERIAL1,

embassy-nrf/src/lib.rs

@@ -86,6 +86,14 @@ pub mod gpiote;
 #[cfg(any(feature = "nrf52832", feature = "nrf52833", feature = "nrf52840"))]
 pub mod i2s;
 #[cfg(not(feature = "_nrf54l"))] // TODO
+#[cfg(any(
+    feature = "nrf52832",
+    feature = "nrf52833",
+    feature = "nrf52840",
+    feature = "_nrf5340-app"
+))]
+pub mod nfct;
+#[cfg(not(feature = "_nrf54l"))] // TODO
 pub mod nvmc;
 #[cfg(not(feature = "_nrf54l"))] // TODO
 #[cfg(any(

embassy-nrf/src/nfct.rs

@@ -0,0 +1,409 @@
+//! NFC tag emulator driver.
+//!
+//! This driver implements support for emulating an ISO14443-3 card. Anticollision and selection
+//! are handled automatically in hardware, then the driver lets you receive and reply to
+//! raw ISO14443-3 frames in software.
+//!
+//! Higher layers such as ISO14443-4 aka ISO-DEP and ISO7816 must be handled on top
+//! in software.
+
+#![macro_use]
+
+use core::future::poll_fn;
+use core::sync::atomic::{compiler_fence, Ordering};
+use core::task::Poll;
+
+use embassy_hal_internal::{into_ref, PeripheralRef};
+use embassy_sync::waitqueue::AtomicWaker;
+pub use vals::{Bitframesdd as SddPat, Discardmode as DiscardMode};
+
+use crate::interrupt::InterruptExt;
+use crate::pac::nfct::vals;
+use crate::peripherals::NFCT;
+use crate::util::slice_in_ram;
+use crate::{interrupt, pac, Peripheral};
+
+/// NFCID1 (aka UID) of different sizes.
+#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
+pub enum NfcId {
+    /// 4-byte UID.
+    SingleSize([u8; 4]),
+    /// 7-byte UID.
+    DoubleSize([u8; 7]),
+    /// 10-byte UID.
+    TripleSize([u8; 10]),
+}
+
+/// The protocol field to be sent in the `SEL_RES` response byte (b6-b7).
+#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
+pub enum SelResProtocol {
+    /// Configured for Type 2 Tag platform.
+    #[default]
+    Type2 = 0,
+    /// Configured for Type 4A Tag platform, compliant with ISO/IEC_14443.
+    Type4A = 1,
+    /// Configured for the NFC-DEP Protocol.
+    NfcDep = 2,
+    /// Configured for the NFC-DEP Protocol and Type 4A Tag platform.
+    NfcDepAndType4A = 3,
+}
+
+/// Config for the `NFCT` peripheral driver.
+#[derive(Clone)]
+pub struct Config {
+    /// NFCID1 to use during autocollision.
+    pub nfcid1: NfcId,
+    /// SDD pattern to be sent in `SENS_RES`.
+    pub sdd_pat: SddPat,
+    /// Platform config to be sent in `SEL_RES`.
+    pub plat_conf: u8,
+    /// Protocol to be sent in the `SEL_RES` response.
+    pub protocol: SelResProtocol,
+}
+
+/// Interrupt handler.
+pub struct InterruptHandler {
+    _private: (),
+}
+
+impl interrupt::typelevel::Handler<interrupt::typelevel::NFCT> for InterruptHandler {
+    unsafe fn on_interrupt() {
+        trace!("irq");
+        pac::NFCT.inten().write(|w| w.0 = 0);
+        WAKER.wake();
+    }
+}
+
+static WAKER: AtomicWaker = AtomicWaker::new();
+
+/// NFC error.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[non_exhaustive]
+pub enum Error {
+    /// Rx Error received while waiting for frame
+    RxError,
+    /// Rx buffer was overrun, increase your buffer size to resolve this
+    RxOverrun,
+    /// Lost field.
+    Deactivated,
+    /// Collision
+    Collision,
+    /// The buffer is not in data RAM. It's most likely in flash, and nRF's DMA cannot access flash.
+    BufferNotInRAM,
+}
+
+/// NFC tag emulator driver.
+pub struct NfcT<'d> {
+    _p: PeripheralRef<'d, NFCT>,
+    rx_buf: [u8; 256],
+    tx_buf: [u8; 256],
+}
+
+impl<'d> NfcT<'d> {
+    /// Create an Nfc Tag driver
+    pub fn new(
+        _p: impl Peripheral<P = NFCT> + 'd,
+        _irq: impl interrupt::typelevel::Binding<interrupt::typelevel::NFCT, InterruptHandler> + 'd,
+        config: &Config,
+    ) -> Self {
+        into_ref!(_p);
+
+        let r = pac::NFCT;
+
+        unsafe {
+            let reset = (r.as_ptr() as *mut u32).add(0xFFC / 4);
+            reset.write_volatile(0);
+            reset.read_volatile();
+            reset.write_volatile(1);
+        }
+
+        let nfcid_size = match &config.nfcid1 {
+            NfcId::SingleSize(bytes) => {
+                r.nfcid1_last().write(|w| w.0 = u32::from_be_bytes(*bytes));
+
+                vals::Nfcidsize::NFCID1SINGLE
+            }
+            NfcId::DoubleSize(bytes) => {
+                let (bytes, chunk) = bytes.split_last_chunk::<4>().unwrap();
+                r.nfcid1_last().write(|w| w.0 = u32::from_be_bytes(*chunk));
+
+                let mut chunk = [0u8; 4];
+                chunk[1..].copy_from_slice(bytes);
+                r.nfcid1_2nd_last().write(|w| w.0 = u32::from_be_bytes(chunk));
+
+                vals::Nfcidsize::NFCID1DOUBLE
+            }
+            NfcId::TripleSize(bytes) => {
+                let (bytes, chunk) = bytes.split_last_chunk::<4>().unwrap();
+                r.nfcid1_last().write(|w| w.0 = u32::from_be_bytes(*chunk));
+
+                let (bytes, chunk2) = bytes.split_last_chunk::<3>().unwrap();
+                let mut chunk = [0u8; 4];
+                chunk[1..].copy_from_slice(chunk2);
+                r.nfcid1_2nd_last().write(|w| w.0 = u32::from_be_bytes(chunk));
+
+                let mut chunk = [0u8; 4];
+                chunk[1..].copy_from_slice(bytes);
+                r.nfcid1_3rd_last().write(|w| w.0 = u32::from_be_bytes(chunk));
+
+                vals::Nfcidsize::NFCID1TRIPLE
+            }
+        };
+
+        r.sensres().write(|w| {
+            w.set_nfcidsize(nfcid_size);
+            w.set_bitframesdd(config.sdd_pat);
+            w.set_platfconfig(config.plat_conf & 0xF);
+        });
+
+        r.selres().write(|w| {
+            w.set_protocol(config.protocol as u8);
+        });
+
+        // errata
+        #[cfg(feature = "nrf52832")]
+        unsafe {
+            // Errata 57 nrf52832 only
+            //(0x40005610 as *mut u32).write_volatile(0x00000005);
+            //(0x40005688 as *mut u32).write_volatile(0x00000001);
+            //(0x40005618 as *mut u32).write_volatile(0x00000000);
+            //(0x40005614 as *mut u32).write_volatile(0x0000003F);
+
+            // Errata 98
+            (0x4000568C as *mut u32).write_volatile(0x00038148);
+        }
+
+        r.inten().write(|w| w.0 = 0);
+
+        interrupt::NFCT.unpend();
+        unsafe { interrupt::NFCT.enable() };
+
+        // clear all shorts
+        r.shorts().write(|_| {});
+
+        let res = Self {
+            _p,
+            tx_buf: [0u8; 256],
+            rx_buf: [0u8; 256],
+        };
+
+        assert!(slice_in_ram(&res.tx_buf), "TX Buf not in ram");
+        assert!(slice_in_ram(&res.rx_buf), "RX Buf not in ram");
+
+        res
+    }
+
+    /// Wait for field on and select.
+    ///
+    /// This waits for the field to become on, and then for a reader to select us. The ISO14443-3
+    /// sense, anticollision and select procedure is handled entirely in hardware.
+    ///
+    /// When this returns, we have successfully been selected as a card. You must then
+    /// loop calling [`receive`](Self::receive) and responding with [`transmit`](Self::transmit).
+    pub async fn activate(&mut self) {
+        let r = pac::NFCT;
+        loop {
+            r.events_fieldlost().write_value(0);
+            r.events_fielddetected().write_value(0);
+            r.tasks_sense().write_value(1);
+
+            // enable autocoll
+            #[cfg(not(feature = "nrf52832"))]
+            r.autocolresconfig().write(|w| w.0 = 0b10);
+
+            r.framedelaymode().write(|w| {
+                w.set_framedelaymode(vals::Framedelaymode::WINDOW_GRID);
+            });
+
+            info!("waiting for field");
+            poll_fn(|cx| {
+                WAKER.register(cx.waker());
+
+                if r.events_fielddetected().read() != 0 {
+                    r.events_fielddetected().write_value(0);
+                    return Poll::Ready(());
+                }
+
+                r.inten().write(|w| {
+                    w.set_fielddetected(true);
+                });
+                Poll::Pending
+            })
+            .await;
+
+            #[cfg(feature = "time")]
+            embassy_time::Timer::after_millis(1).await; // workaround errata 190
+
+            r.events_selected().write_value(0);
+            r.tasks_activate().write_value(1);
+
+            trace!("Waiting to be selected");
+            poll_fn(|cx| {
+                let r = pac::NFCT;
+
+                WAKER.register(cx.waker());
+
+                if r.events_selected().read() != 0 || r.events_fieldlost().read() != 0 {
+                    return Poll::Ready(());
+                }
+
+                r.inten().write(|w| {
+                    w.set_selected(true);
+                    w.set_fieldlost(true);
+                });
+                Poll::Pending
+            })
+            .await;
+            if r.events_fieldlost().read() != 0 {
+                continue;
+            }
+
+            // TODO: add support for "window" frame delay, which is technically
+            // needed to be compliant with iso14443-4
+            r.framedelaymode().write(|w| {
+                w.set_framedelaymode(vals::Framedelaymode::FREE_RUN);
+            });
+
+            // disable autocoll
+            #[cfg(not(feature = "nrf52832"))]
+            r.autocolresconfig().write(|w| w.0 = 0b11u32);
+
+            return;
+        }
+    }
+
+    /// Transmit an ISO14443-3 frame to the reader.
+    ///
+    /// You must call this only after receiving a frame with [`receive`](Self::receive),
+    /// and only once. Higher-layer protocols usually define timeouts, so calling this
+    /// too late can cause things to fail.
+    ///
+    /// This will fail with [`Error::Deactivated`] if we have been deselected due to either
+    /// the field being switched off or due to the ISO14443 state machine. When this happens,
+    /// you must stop calling [`receive`](Self::receive) and [`transmit`](Self::transmit), reset
+    /// all protocol state, and go back to calling [`activate`](Self::activate).
+    pub async fn transmit(&mut self, buf: &[u8]) -> Result<(), Error> {
+        let r = pac::NFCT;
+
+        //Setup DMA
+        self.tx_buf[..buf.len()].copy_from_slice(buf);
+        r.packetptr().write_value(self.tx_buf.as_ptr() as u32);
+        r.maxlen().write(|w| w.0 = buf.len() as _);
+
+        // Set packet length
+        r.txd().amount().write(|w| {
+            w.set_txdatabits(0);
+            w.set_txdatabytes(buf.len() as _);
+        });
+
+        r.txd().frameconfig().write(|w| {
+            w.set_crcmodetx(true);
+            w.set_discardmode(DiscardMode::DISCARD_END);
+            w.set_parity(true);
+            w.set_sof(true);
+        });
+
+        r.events_error().write_value(0);
+        r.events_txframeend().write_value(0);
+        r.errorstatus().write(|w| w.0 = 0xffff_ffff);
+
+        // Start starttx task
+        compiler_fence(Ordering::SeqCst);
+        r.tasks_starttx().write_value(1);
+
+        poll_fn(move |cx| {
+            trace!("polling tx");
+            let r = pac::NFCT;
+            WAKER.register(cx.waker());
+
+            if r.events_fieldlost().read() != 0 {
+                return Poll::Ready(Err(Error::Deactivated));
+            }
+
+            if r.events_txframeend().read() != 0 {
+                trace!("Txframend hit, should be finished trasmitting");
+                return Poll::Ready(Ok(()));
+            }
+
+            if r.events_error().read() != 0 {
+                trace!("Got error?");
+                warn!("errors: {:08x}", r.errorstatus().read().0);
+                r.events_error().write_value(0);
+                return Poll::Ready(Err(Error::RxError));
+            }
+
+            r.inten().write(|w| {
+                w.set_txframeend(true);
+                w.set_error(true);
+                w.set_fieldlost(true);
+            });
+
+            Poll::Pending
+        })
+        .await
+    }
+
+    /// Receive an ISO14443-3 frame from the reader.
+    ///
+    /// After calling this, you must send back a response with [`transmit`](Self::transmit),
+    /// and only once. Higher-layer protocols usually define timeouts, so calling this
+    /// too late can cause things to fail.
+    pub async fn receive(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
+        let r = pac::NFCT;
+
+        r.rxd().frameconfig().write(|w| {
+            w.set_crcmoderx(true);
+            w.set_parity(true);
+            w.set_sof(true);
+        });
+
+        //Setup DMA
+        r.packetptr().write_value(self.rx_buf.as_mut_ptr() as u32);
+        r.maxlen().write(|w| w.0 = self.rx_buf.len() as _);
+
+        // Reset and enable the end event
+        r.events_rxframeend().write_value(0);
+        r.events_rxerror().write_value(0);
+
+        // Start enablerxdata only after configs are finished writing
+        compiler_fence(Ordering::SeqCst);
+        r.tasks_enablerxdata().write_value(1);
+
+        poll_fn(move |cx| {
+            trace!("polling rx");
+            let r = pac::NFCT;
+            WAKER.register(cx.waker());
+
+            if r.events_fieldlost().read() != 0 {
+                return Poll::Ready(Err(Error::Deactivated));
+            }
+
+            if r.events_rxerror().read() != 0 {
+                trace!("RXerror got in recv frame, should be back in idle state");
+                r.events_rxerror().write_value(0);
+                warn!("errors: {:08x}", r.errorstatus().read().0);
+                return Poll::Ready(Err(Error::RxError));
+            }
+
+            if r.events_rxframeend().read() != 0 {
+                trace!("RX Frameend got in recv frame, should have data");
+                r.events_rxframeend().write_value(0);
+                return Poll::Ready(Ok(()));
+            }
+
+            r.inten().write(|w| {
+                w.set_rxframeend(true);
+                w.set_rxerror(true);
+                w.set_fieldlost(true);
+            });
+
+            Poll::Pending
+        })
+        .await?;
+
+        let n = r.rxd().amount().read().rxdatabytes() as usize - 2;
+        buf[..n].copy_from_slice(&self.rx_buf[..n]);
+        Ok(n)
+    }
+}

examples/nrf52840/src/bin/nfct.rs

@@ -0,0 +1,79 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_nrf::config::HfclkSource;
+use embassy_nrf::nfct::{Config as NfcConfig, NfcId, NfcT};
+use embassy_nrf::{bind_interrupts, nfct};
+use {defmt_rtt as _, embassy_nrf as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    NFCT => nfct::InterruptHandler;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let mut config = embassy_nrf::config::Config::default();
+    config.hfclk_source = HfclkSource::ExternalXtal;
+    let p = embassy_nrf::init(config);
+
+    dbg!("Setting up...");
+    let config = NfcConfig {
+        nfcid1: NfcId::DoubleSize([0x04, 0x68, 0x95, 0x71, 0xFA, 0x5C, 0x64]),
+        sdd_pat: nfct::SddPat::SDD00100,
+        plat_conf: 0b0000,
+        protocol: nfct::SelResProtocol::Type4A,
+    };
+
+    let mut nfc = NfcT::new(p.NFCT, Irqs, &config);
+
+    let mut buf = [0u8; 256];
+
+    loop {
+        info!("activating");
+        nfc.activate().await;
+
+        loop {
+            info!("rxing");
+            let n = match nfc.receive(&mut buf).await {
+                Ok(n) => n,
+                Err(e) => {
+                    error!("rx error {}", e);
+                    break;
+                }
+            };
+            let req = &buf[..n];
+            info!("received frame {:02x}", req);
+
+            let mut deselect = false;
+            let resp = match req {
+                [0xe0, ..] => {
+                    info!("Got RATS, tx'ing ATS");
+                    &[0x06, 0x77, 0x77, 0x81, 0x02, 0x80][..]
+                }
+                [0xc2] => {
+                    info!("Got deselect!");
+                    deselect = true;
+                    &[0xc2]
+                }
+                _ => {
+                    info!("Got unknown command!");
+                    &[0xFF]
+                }
+            };
+
+            match nfc.transmit(resp).await {
+                Ok(()) => {}
+                Err(e) => {
+                    error!("tx error {}", e);
+                    break;
+                }
+            }
+
+            if deselect {
+                break;
+            }
+        }
+    }
+}