6 files changed, 962 insertions, 1 deletions

diff --git a/embassy-nxp/Cargo.toml b/embassy-nxp/Cargo.toml
index 9fa48c4b9..cdfaee64d 100644
--- a/embassy-nxp/Cargo.toml
+++ b/embassy-nxp/Cargo.toml
@@ -24,7 +24,8 @@ log = { version = "0.4.27", optional = true }
 embassy-time = { version = "0.4.0", path = "../embassy-time", optional = true }
 embassy-time-driver = { version = "0.2", path = "../embassy-time-driver", optional = true }
 embassy-time-queue-utils = { version = "0.2", path = "../embassy-time-queue-utils", optional = true }
-
+embedded-io = "0.6.1"
+embedded-hal-02 = { package = "embedded-hal", version = "0.2.6", features = ["unproven"] }
 ## Chip dependencies
 lpc55-pac = { version = "0.5.0", optional = true }
 nxp-pac = { version = "0.1.0", optional = true, git = "https://github.com/i509VCB/nxp-pac", rev = "be4dd0936c20d5897364a381b1d95a99514c1e7e" }
diff --git a/embassy-nxp/src/chips/lpc55.rs b/embassy-nxp/src/chips/lpc55.rs
index c95218af0..e168ced00 100644
--- a/embassy-nxp/src/chips/lpc55.rs
+++ b/embassy-nxp/src/chips/lpc55.rs
@@ -67,4 +67,13 @@ embassy_hal_internal::peripherals! {
     PIO1_29,
     PIO1_30,
     PIO1_31,
+
+    USART0,
+    USART1,
+    USART2,
+    USART3,
+    USART4,
+    USART5,
+    USART6,
+    USART7
 }
diff --git a/embassy-nxp/src/lib.rs b/embassy-nxp/src/lib.rs
index b2e910f7e..3fcb14b7e 100644
--- a/embassy-nxp/src/lib.rs
+++ b/embassy-nxp/src/lib.rs
@@ -6,6 +6,8 @@ pub(crate) mod fmt;
 pub mod gpio;
 #[cfg(feature = "lpc55")]
 pub mod pint;
+#[cfg(feature = "lpc55")]
+pub mod usart;
 
 #[cfg(feature = "_time_driver")]
 #[cfg_attr(feature = "time-driver-pit", path = "time_driver/pit.rs")]
@@ -115,3 +117,21 @@ impl Iterator for BitIter {
         }
     }
 }
+
+trait SealedMode {}
+
+/// UART mode.
+#[allow(private_bounds)]
+pub trait Mode: SealedMode {}
+
+macro_rules! impl_mode {
+    ($name:ident) => {
+        impl SealedMode for $name {}
+        impl Mode for $name {}
+    };
+}
+
+/// Blocking mode.
+pub struct Blocking;
+
+impl_mode!(Blocking);
diff --git a/embassy-nxp/src/usart.rs b/embassy-nxp/src/usart.rs
new file mode 100644
index 000000000..009c251e2
--- /dev/null
+++ b/embassy-nxp/src/usart.rs
@@ -0,0 +1,6 @@
+//! Universal Synchronous/Asynchronous Receiver/Transmitter (USART) driver.
+#![macro_use]
+
+#[cfg_attr(feature = "lpc55", path = "./usart/lpc55.rs")]
+mod inner;
+pub use inner::*;
diff --git a/embassy-nxp/src/usart/lpc55.rs b/embassy-nxp/src/usart/lpc55.rs
new file mode 100644
index 000000000..3f7456a2e
--- /dev/null
+++ b/embassy-nxp/src/usart/lpc55.rs
@@ -0,0 +1,885 @@
+use core::marker::PhantomData;
+
+use embassy_hal_internal::{Peri, PeripheralType};
+use embedded_io::{self, ErrorKind};
+pub use sealed::SealedInstance;
+
+use crate::gpio::AnyPin;
+use crate::{Blocking, Mode};
+
+/// Serial error
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[non_exhaustive]
+pub enum Error {
+    /// Triggered when the FIFO (or shift-register) is overflowed.
+    Overrun,
+    /// Triggered when there is a parity mismatch between what's received and
+    /// our settings.
+    Parity,
+    /// Triggered when the received character didn't have a valid stop bit.
+    Framing,
+    /// Triggered when the receiver detects noise
+    Noise,
+    /// Triggered when the receiver gets a break
+    Break,
+}
+
+impl embedded_io::Error for Error {
+    fn kind(&self) -> ErrorKind {
+        match self {
+            Error::Overrun => ErrorKind::Other,
+            Error::Parity => ErrorKind::InvalidData,
+            Error::Framing => ErrorKind::InvalidData,
+            Error::Noise => ErrorKind::Other,
+            Error::Break => ErrorKind::Interrupted,
+        }
+    }
+}
+/// Word length.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum DataBits {
+    /// 7 bits data length.
+    DataBits7,
+    /// 8 bits data length.
+    DataBits8,
+    /// 9 bits data length. The 9th bit is commonly used for addressing in multidrop mode.
+    DataBits9,
+}
+
+impl DataBits {
+    fn bits(&self) -> u8 {
+        match self {
+            Self::DataBits7 => 0b00,
+            Self::DataBits8 => 0b01,
+            Self::DataBits9 => 0b10,
+        }
+    }
+}
+
+/// Parity bit.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum Parity {
+    /// No parity.
+    ParityNone,
+    /// Even parity.
+    ParityEven,
+    /// Odd parity.
+    ParityOdd,
+}
+
+impl Parity {
+    fn bits(&self) -> u8 {
+        match self {
+            Self::ParityNone => 0b00,
+            Self::ParityEven => 0b10,
+            Self::ParityOdd => 0b11,
+        }
+    }
+}
+
+/// Stop bits.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum StopBits {
+    /// 1 stop bit.
+    Stop1,
+    /// 2 stop bits. This setting should only be used for asynchronous communication.
+    Stop2,
+}
+
+impl StopBits {
+    fn bits(&self) -> bool {
+        return match self {
+            Self::Stop1 => false,
+            Self::Stop2 => true,
+        };
+    }
+}
+
+/// UART config.
+#[non_exhaustive]
+#[derive(Clone, Debug)]
+pub struct Config {
+    /// Baud rate.
+    pub baudrate: u32,
+    /// Word length.
+    pub data_bits: DataBits,
+    /// Stop bits.
+    pub stop_bits: StopBits,
+    /// Parity bit.
+    pub parity: Parity,
+    /// Invert the tx pin output
+    pub invert_tx: bool,
+    /// Invert the rx pin input
+    pub invert_rx: bool,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            baudrate: 9600,
+            data_bits: DataBits::DataBits8,
+            stop_bits: StopBits::Stop1,
+            parity: Parity::ParityNone,
+            invert_rx: false,
+            invert_tx: false,
+        }
+    }
+}
+
+/// # Type parameters
+/// 'd: the lifetime marker ensuring correct borrow checking for peripherals used at compile time
+/// T: the peripheral instance type allowing usage of peripheral specific registers
+/// M: the operating mode of USART peripheral
+pub struct Usart<'d, T: Instance, M: Mode> {
+    tx: UsartTx<'d, T, M>,
+    rx: UsartRx<'d, T, M>,
+}
+
+pub struct UsartTx<'d, T: Instance, M: Mode> {
+    phantom: PhantomData<(&'d (), T, M)>,
+}
+
+pub struct UsartRx<'d, T: Instance, M: Mode> {
+    phantom: PhantomData<(&'d (), T, M)>,
+}
+
+impl<'d, T: Instance, M: Mode> UsartTx<'d, T, M> {
+    pub fn new(_usart: Peri<'d, T>, tx: Peri<'d, impl TxPin<T>>, config: Config) -> Self {
+        Usart::<T, M>::init(Some(tx.into()), None, config);
+        Self::new_inner()
+    }
+
+    #[inline]
+    fn new_inner() -> Self {
+        Self { phantom: PhantomData }
+    }
+
+    pub fn blocking_write(&mut self, buffer: &[u8]) -> Result<(), Error> {
+        T::blocking_write(buffer)
+    }
+
+    pub fn blocking_flush(&mut self) -> Result<(), Error> {
+        T::blocking_flush()
+    }
+
+    pub fn tx_busy(&self) -> bool {
+        T::tx_busy()
+    }
+}
+
+impl<'d, T: Instance> UsartTx<'d, T, Blocking> {
+    pub fn new_blocking(_usart: Peri<'d, T>, tx: Peri<'d, impl TxPin<T>>, config: Config) -> Self {
+        Usart::<T, Blocking>::init(Some(tx.into()), None, config);
+        Self::new_inner()
+    }
+}
+
+impl<'d, T: Instance, M: Mode> UsartRx<'d, T, M> {
+    pub fn new(_usart: Peri<'d, T>, rx: Peri<'d, impl RxPin<T>>, config: Config) -> Self {
+        Usart::<T, M>::init(None, Some(rx.into()), config);
+        Self::new_inner()
+    }
+
+    #[inline]
+    fn new_inner() -> Self {
+        Self { phantom: PhantomData }
+    }
+
+    pub fn blocking_read(&mut self, mut buffer: &mut [u8]) -> Result<(), Error> {
+        while !buffer.is_empty() {
+            match Self::drain_fifo(self, buffer) {
+                Ok(0) => continue, // Wait for more data
+                Ok(n) => buffer = &mut buffer[n..],
+                Err((_, err)) => return Err(err),
+            }
+        }
+        Ok(())
+    }
+
+    /// Returns:
+    /// - Ok(n) -> read n bytes
+    /// - Err(n, Error) -> read n-1 bytes, but encountered an error while reading nth byte
+    fn drain_fifo(&mut self, buffer: &mut [u8]) -> Result<usize, (usize, Error)> {
+        T::drain_fifo(buffer)
+    }
+}
+
+impl<'d, T: Instance> UsartRx<'d, T, Blocking> {
+    pub fn new_blocking(_usart: Peri<'d, T>, rx: Peri<'d, impl RxPin<T>>, config: Config) -> Self {
+        Usart::<T, Blocking>::init(None, Some(rx.into()), config);
+        Self::new_inner()
+    }
+}
+
+impl<'d, T: Instance> Usart<'d, T, Blocking> {
+    pub fn new_blocking(
+        usart: Peri<'d, T>,
+        tx: Peri<'d, impl TxPin<T>>,
+        rx: Peri<'d, impl RxPin<T>>,
+        config: Config,
+    ) -> Self {
+        Self::new_inner(usart, tx.into(), rx.into(), config)
+    }
+}
+
+impl<'d, T: Instance, M: Mode> Usart<'d, T, M> {
+    fn new_inner(_usart: Peri<'d, T>, mut tx: Peri<'d, AnyPin>, mut rx: Peri<'d, AnyPin>, config: Config) -> Self {
+        Self::init(Some(tx.reborrow()), Some(rx.reborrow()), config);
+        Self {
+            tx: UsartTx::new_inner(),
+            rx: UsartRx::new_inner(),
+        }
+    }
+
+    fn init(_tx: Option<Peri<'_, AnyPin>>, _rx: Option<Peri<'_, AnyPin>>, config: Config) {
+        T::enable_clock();
+        T::reset_flexcomm();
+        let source_clock: u32 = T::select_clock(config.baudrate);
+        T::configure_flexcomm();
+        T::tx_pin_config();
+        T::rx_pin_config();
+        Self::set_baudrate(source_clock, config.baudrate);
+        T::configure_usart(config);
+        T::disable_dma();
+        T::enable_usart();
+    }
+
+    fn set_baudrate(source_clock: u32, baudrate: u32) {
+        // There are two types of dividers: integer divider (baud rate generator register and oversample selection value)
+        // and fractional divider (fractional rate divider).
+        // For oversampling, the default is industry standard 16x oversampling, i.e. OSRVAL = 15
+
+        // The formulas are:
+
+        // FLCK = (clock selected via FCCLKSEL) / (1 + MULT / DIV)
+        // DIV is always 256, then:
+        // FLCK = (clock selected via FCCLKSEL) / (1 + MULT / 256)
+
+        // Baud rate = [FCLK / (OSRVAL+1)] / (BRGVAL + 1) =>
+        // Baud rate = [FCLK / 16] / (BRGVAL + 1)
+
+        // There are 2 unknowns: MULT and BRGVAL.
+        // MULT is responsible for fractional division
+        // BRGVAL is responsible for integer division
+
+        //  The Fractional Rate Generator can be used to obtain more precise baud rates when the
+        //  function clock is not a good multiple of standard (or otherwise desirable) baud rates.
+        //  The FRG is typically set up to produce an integer multiple of the highest required baud
+        //  rate, or a very close approximation. The BRG is then used to obtain the actual baud rate
+        //  needed.
+
+        // Firstly, BRGVAL is calculated to get the raw clock which is a rough approximation that has to be adjusted
+        // so that the desired baud rate is obtained.
+        // Secondly, MULT is calculated to ultimately 'chisel' the clock to get the baud rate.
+        // The deduced formulas are written below.
+
+        let brg_value = (source_clock / (16 * baudrate)).min(255);
+        let raw_clock = source_clock / (16 * brg_value);
+        let mult_value = ((raw_clock * 256 / baudrate) - 256).min(255);
+        T::set_baudrate(mult_value as u8, brg_value as u8);
+    }
+}
+
+impl<'d, T: Instance, M: Mode> Usart<'d, T, M> {
+    /// Transmit the provided buffer blocking execution until done.
+    pub fn blocking_write(&mut self, buffer: &[u8]) -> Result<(), Error> {
+        self.tx.blocking_write(buffer)
+    }
+
+    /// Flush USART TX blocking execution until done.
+    pub fn blocking_flush(&mut self) -> Result<(), Error> {
+        self.tx.blocking_flush()
+    }
+
+    /// Read from USART RX blocking execution until done.
+    pub fn blocking_read(&mut self, buffer: &mut [u8]) -> Result<(), Error> {
+        self.rx.blocking_read(buffer)
+    }
+
+    /// Check if UART is busy transmitting.
+    pub fn tx_busy(&self) -> bool {
+        self.tx.tx_busy()
+    }
+
+    /// Split the Usart into a transmitter and receiver, which is particularly
+    /// useful when having two tasks correlating to transmitting and receiving.
+    pub fn split(self) -> (UsartTx<'d, T, M>, UsartRx<'d, T, M>) {
+        (self.tx, self.rx)
+    }
+
+    /// Split the Usart into a transmitter and receiver by mutable reference,
+    /// which is particularly useful when having two tasks correlating to
+    /// transmitting and receiving.
+    pub fn split_ref(&mut self) -> (&mut UsartTx<'d, T, M>, &mut UsartRx<'d, T, M>) {
+        (&mut self.tx, &mut self.rx)
+    }
+}
+
+impl<'d, T: Instance, M: Mode> embedded_hal_02::blocking::serial::Write<u8> for UsartTx<'d, T, M> {
+    type Error = Error;
+
+    fn bwrite_all(&mut self, buffer: &[u8]) -> Result<(), Self::Error> {
+        self.blocking_write(buffer)
+    }
+
+    fn bflush(&mut self) -> Result<(), Self::Error> {
+        self.blocking_flush()
+    }
+}
+
+impl<'d, T: Instance, M: Mode> embedded_hal_02::blocking::serial::Write<u8> for Usart<'d, T, M> {
+    type Error = Error;
+
+    fn bwrite_all(&mut self, buffer: &[u8]) -> Result<(), Self::Error> {
+        self.blocking_write(buffer)
+    }
+
+    fn bflush(&mut self) -> Result<(), Self::Error> {
+        self.blocking_flush()
+    }
+}
+
+impl<'d, T: Instance> embedded_io::ErrorType for UsartTx<'d, T, Blocking> {
+    type Error = Error;
+}
+
+impl<'d, T: Instance> embedded_io::Write for UsartTx<'d, T, Blocking> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        self.blocking_write(buf).map(|_| buf.len())
+    }
+
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        self.blocking_flush()
+    }
+}
+
+impl<'d, T: Instance> embedded_io::ErrorType for UsartRx<'d, T, Blocking> {
+    type Error = Error;
+}
+
+impl<'d, T: Instance> embedded_io::Read for UsartRx<'d, T, Blocking> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        self.blocking_read(buf).map(|_| buf.len())
+    }
+}
+
+impl<'d, T: Instance> embedded_io::ErrorType for Usart<'d, T, Blocking> {
+    type Error = Error;
+}
+
+impl<'d, T: Instance> embedded_io::Write for Usart<'d, T, Blocking> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        self.blocking_write(buf).map(|_| buf.len())
+    }
+
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        self.blocking_flush()
+    }
+}
+
+impl<'d, T: Instance> embedded_io::Read for Usart<'d, T, Blocking> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        self.blocking_read(buf).map(|_| buf.len())
+    }
+}
+
+type UsartRegBlock = crate::pac::usart0::RegisterBlock;
+
+mod sealed {
+    use crate::usart::inner::UsartRegBlock;
+    use crate::usart::{Config, Error};
+    pub trait SealedInstance {
+        fn usart_reg() -> &'static UsartRegBlock;
+        fn enable_clock();
+        fn select_clock(baudrate: u32) -> u32;
+        fn configure_flexcomm();
+        fn set_baudrate(mult_value: u8, brg_value: u8);
+        fn reset_flexcomm();
+        fn tx_pin_config();
+        fn rx_pin_config();
+
+        fn configure_usart(config: Config) {
+            // See section 34.6.1
+            Self::usart_reg().cfg.modify(|_, w| {
+                // LIN break mode enable
+                w.linmode()
+                    // Disabled. Break detect and generate is configured for normal operation.
+                    .disabled()
+                    //CTS Enable. Determines whether CTS is used for flow control. CTS can be from the
+                    //input pin, or from the USART’s own RTS if loopback mode is enabled.
+                    .ctsen()
+                    // No flow control. The transmitter does not receive any automatic flow control signal.
+                    .disabled()
+                    // Selects synchronous or asynchronous operation.
+                    .syncen()
+                    .asynchronous_mode()
+                    // Selects the clock polarity and sampling edge of received data in synchronous mode.
+                    .clkpol()
+                    .rising_edge()
+                    // Synchronous mode Master select.
+                    .syncmst()
+                    // When synchronous mode is enabled, the USART is a master.
+                    .master()
+                    // Selects data loopback mode
+                    .loop_()
+                    // Normal operation
+                    .normal()
+                    // Output Enable Turnaround time enable for RS-485 operation.
+                    .oeta()
+                    // Disabled. If selected by OESEL, the Output Enable signal deasserted at the end of
+                    // the last stop bit of a transmission.
+                    .disabled()
+                    // Output enable select.
+                    .oesel()
+                    // Standard. The RTS signal is used as the standard flow control function.
+                    .standard()
+                    // Automatic address matching enable.
+                    .autoaddr()
+                    // Disabled. When addressing is enabled by ADDRDET, address matching is done by
+                    // software. This provides the possibility of versatile addressing (e.g. respond to more
+                    // than one address)
+                    .disabled()
+                    // Output enable polarity.
+                    .oepol()
+                    // Low. If selected by OESEL, the output enable is active low.
+                    .low()
+            });
+
+            Self::usart_reg().cfg.modify(|_, w| unsafe {
+                w.datalen()
+                    .bits(config.data_bits.bits())
+                    .paritysel()
+                    .bits(config.parity.bits())
+                    .stoplen()
+                    .bit(config.stop_bits.bits())
+                    .rxpol()
+                    .bit(config.invert_rx)
+                    .txpol()
+                    .bit(config.invert_tx)
+            });
+        }
+        fn disable_dma() {
+            Self::usart_reg()
+                .fifocfg
+                .modify(|_, w| w.dmatx().disabled().dmarx().disabled());
+        }
+        fn enable_usart() {
+            Self::usart_reg()
+                .fifocfg
+                .modify(|_, w| w.enabletx().enabled().enablerx().enabled());
+            Self::usart_reg().cfg.modify(|_, w| w.enable().enabled());
+            while Self::usart_reg().fifostat.read().rxnotempty().bit_is_set() {
+                let _ = Self::usart_reg().fiford.read().bits();
+            }
+        }
+        fn blocking_write(buffer: &[u8]) -> Result<(), Error> {
+            for &b in buffer {
+                while Self::usart_reg().fifostat.read().txnotfull().bit_is_clear() {}
+                Self::usart_reg()
+                    .fifowr
+                    .modify(|_, w| unsafe { w.txdata().bits(b as u16) });
+            }
+            Ok(())
+        }
+        fn blocking_flush() -> Result<(), Error> {
+            while Self::usart_reg().fifostat.read().txempty().bit_is_clear() {}
+            Ok(())
+        }
+        fn tx_busy() -> bool {
+            Self::usart_reg().fifostat.read().txempty().bit_is_clear()
+        }
+        fn drain_fifo(buffer: &mut [u8]) -> Result<usize, (usize, Error)> {
+            for (i, b) in buffer.iter_mut().enumerate() {
+                while Self::usart_reg().fifostat.read().rxnotempty().bit_is_clear() {}
+
+                if Self::usart_reg().fifostat.read().rxerr().bit_is_set() {
+                    return Err((i, Error::Overrun));
+                } else if Self::usart_reg().fifordnopop.read().parityerr().bit_is_set() {
+                    return Err((i, Error::Parity));
+                } else if Self::usart_reg().fifordnopop.read().framerr().bit_is_set() {
+                    return Err((i, Error::Framing));
+                } else if Self::usart_reg().fifordnopop.read().rxnoise().bit_is_set() {
+                    return Err((i, Error::Noise));
+                } else if Self::usart_reg().intstat.read().deltarxbrk().bit_is_set() {
+                    return Err((i, Error::Break));
+                }
+                let dr = Self::usart_reg().fiford.read().bits() as u8;
+                *b = dr;
+            }
+            Ok(buffer.len())
+        }
+    }
+}
+
+/// UART instance.
+#[allow(private_bounds)]
+pub trait Instance: sealed::SealedInstance + PeripheralType {}
+
+#[macro_export]
+macro_rules! impl_instance {
+    (
+        $inst:ident,
+        usart_peripheral: $USARTX:ident,
+        usart_crate: $usartX:ident,
+
+        flexcomm: {
+          field: $FLEXCOMM_FIELD:ident,
+          clock_field: $FLEXCOMM_CLK_FIELD:ident
+        },
+
+        reset: {
+            bit: $RESET_BIT:ident
+        },
+
+        clock: {
+            sel_field: $CLKSEL_FIELD:ident,
+            frg_field: $FRG_FIELD:ident
+        },
+
+        pins: {
+            tx: $TX_IOCON:ident => $TX_FUNC:expr,
+            rx: $RX_IOCON:ident => $RX_FUNC:expr
+        }
+
+    ) => {
+        impl $crate::usart::SealedInstance for $crate::peripherals::$inst {
+            fn usart_reg() -> &'static UsartRegBlock {
+                unsafe { &*$crate::pac::$USARTX::ptr() }
+            }
+
+            fn enable_clock() {
+                critical_section::with(|_cs| {
+                    if syscon_reg().ahbclkctrl0.read().iocon().is_disable() {
+                        syscon_reg().ahbclkctrl0.modify(|_, w| w.iocon().enable());
+                    }
+                    if syscon_reg().ahbclkctrl1.read().$FLEXCOMM_CLK_FIELD().is_disable() {
+                        syscon_reg()
+                            .ahbclkctrl1
+                            .modify(|_, w| w.$FLEXCOMM_CLK_FIELD().enable());
+                    }
+                });
+            }
+
+            fn configure_flexcomm() {
+                let flexcomm = unsafe { &*$crate::pac::$FLEXCOMM_FIELD::ptr() };
+                flexcomm.pselid.modify(|_, w| w.persel().usart());
+            }
+
+            fn reset_flexcomm() {
+                syscon_reg().presetctrl1.modify(|_, w| w.$RESET_BIT().set_bit());
+                syscon_reg().presetctrl1.modify(|_, w| w.$RESET_BIT().clear_bit());
+            }
+
+            fn select_clock(baudrate: u32) -> u32 {
+                // Adaptive clock choice based on baud rate
+                // To get the desired baud rate, it is essential to choose the clock bigger than baud rate so that it can be 'chiseled'
+                // There are two types of dividers: integer divider (baud rate generator register and oversample selection value)
+                // and fractional divider (fractional rate divider).
+
+                // By default, oversampling rate is 16 which is an industry standard.
+                // That means 16 clocks are used to deliver the byte to recipient.
+                // In this way the probability of getting correct bytes instead of noise directly increases as oversampling increases as well.
+
+                // Minimum and maximum values were computed taking these formulas into account:
+                // For minimum value, MULT = 0, BRGVAL = 0
+                // For maximum value, MULT = 255, BRGVAL = 255
+                // Flexcomm Interface function clock = (clock selected via FCCLKSEL) / (1 + MULT / DIV)
+                // By default, OSRVAL = 15 (see above)
+                // Baud rate = [FCLK / (OSRVAL+1)] / (BRGVAL + 1)
+                return match baudrate {
+                    750_001..=6000000 => {
+                        syscon_reg().$CLKSEL_FIELD().write(|w| w.sel().enum_0x3()); // 96 MHz
+                        96_000_000
+                    }
+                    1501..=750_000 => {
+                        syscon_reg().$CLKSEL_FIELD().write(|w| w.sel().enum_0x2()); // 12 MHz
+                        12_000_000
+                    }
+                    121..=1500 => {
+                        syscon_reg().$CLKSEL_FIELD().write(|w| w.sel().enum_0x4()); // 1 MHz
+                        1_000_000
+                    }
+                    _ => {
+                        panic!("{} baudrate is not permitted in this mode", baudrate);
+                    }
+                };
+            }
+
+            fn set_baudrate(mult_value: u8, brg_value: u8) {
+                // FCLK =  (clock selected via FCCLKSEL) / (1+ MULT / DIV)
+                // Remark: To use the fractional baud rate generator, 0xFF must be wirtten to the DIV value
+                // to yield a denominator vale of 256. All other values are not supported
+                syscon_reg()
+                    .$FRG_FIELD()
+                    .modify(|_, w| unsafe { w.div().bits(0xFF).mult().bits(mult_value as u8) });
+
+                // Baud rate = [FCLK / (OSRVAL+1)] / (BRGVAL + 1)
+                // By default, oversampling is 16x, i.e. OSRVAL = 15
+
+                // Typical industry standard USARTs use a 16x oversample clock to transmit and receive
+                // asynchronous data. This is the number of BRG clocks used for one data bit. The
+                // Oversample Select Register (OSR) allows this USART to use a 16x down to a 5x
+                // oversample clock. There is no oversampling in synchronous modes.
+                Self::usart_reg()
+                    .brg
+                    .modify(|_, w| unsafe { w.brgval().bits((brg_value - 1) as u16) });
+            }
+
+            fn tx_pin_config() {
+                iocon_reg().$TX_IOCON.modify(|_, w| unsafe {
+                    w.func()
+                        .bits($TX_FUNC)
+                        .digimode()
+                        .digital()
+                        .slew()
+                        .standard()
+                        .mode()
+                        .inactive()
+                        .invert()
+                        .disabled()
+                        .od()
+                        .normal()
+                });
+            }
+
+            fn rx_pin_config() {
+                iocon_reg().$RX_IOCON.modify(|_, w| unsafe {
+                    w.func()
+                        .bits($RX_FUNC)
+                        .digimode()
+                        .digital()
+                        .slew()
+                        .standard()
+                        .mode()
+                        .inactive()
+                        .invert()
+                        .disabled()
+                        .od()
+                        .normal()
+                });
+            }
+        }
+
+        impl $crate::usart::Instance for $crate::peripherals::$inst {}
+    };
+}
+
+impl_instance!(USART0, usart_peripheral: USART0, usart_crate: usart0,
+    flexcomm: {
+        field: FLEXCOMM0,
+        clock_field: fc0
+    },
+
+    reset: {
+        bit: fc0_rst
+    },
+
+    clock: {
+        sel_field: fcclksel0,
+        frg_field: flexfrg0ctrl
+    },
+
+    pins: {
+        tx: pio1_6 => 1,
+        rx: pio1_5 => 1
+    }
+);
+
+impl_instance!(USART1, usart_peripheral: USART1, usart_crate: usart1,
+    flexcomm: {
+        field: FLEXCOMM1,
+        clock_field: fc1
+    },
+
+    reset: {
+        bit: fc1_rst
+    },
+
+    clock: {
+        sel_field: fcclksel1,
+        frg_field: flexfrg1ctrl
+    },
+
+    pins: {
+        tx: pio1_11 => 2,
+        rx: pio1_10 => 2
+    }
+);
+
+impl_instance!(USART2, usart_peripheral: USART2, usart_crate: usart2,
+    flexcomm: {
+        field: FLEXCOMM2,
+        clock_field: fc2
+    },
+
+    reset: {
+        bit: fc2_rst
+    },
+
+    clock: {
+        sel_field: fcclksel2,
+        frg_field: flexfrg2ctrl
+    },
+
+    pins: {
+        tx: pio0_27 => 1,
+        rx: pio1_24 => 1
+    }
+);
+
+impl_instance!(USART3, usart_peripheral: USART3, usart_crate: usart3,
+    flexcomm: {
+        field: FLEXCOMM3,
+        clock_field: fc3
+    },
+
+    reset: {
+        bit: fc3_rst
+    },
+
+    clock: {
+        sel_field: fcclksel3,
+        frg_field: flexfrg3ctrl
+    },
+
+    pins: {
+        tx: pio0_2 => 1,
+        rx: pio0_3 => 1
+    }
+);
+
+impl_instance!(USART4, usart_peripheral: USART4, usart_crate: usart4,
+    flexcomm: {
+        field: FLEXCOMM4,
+        clock_field: fc4
+    },
+
+    reset: {
+        bit: fc4_rst
+    },
+
+    clock: {
+        sel_field: fcclksel4,
+        frg_field: flexfrg4ctrl
+    },
+
+    pins: {
+        tx: pio0_16 => 1,
+        rx: pio0_5 => 2
+    }
+);
+
+impl_instance!(USART5, usart_peripheral: USART5, usart_crate: usart5,
+    flexcomm: {
+        field: FLEXCOMM5,
+        clock_field: fc5
+    },
+
+    reset: {
+        bit: fc5_rst
+    },
+
+    clock: {
+        sel_field: fcclksel5,
+        frg_field: flexfrg5ctrl
+    },
+
+    pins: {
+        tx: pio0_9 => 3,
+        rx: pio0_8 => 3
+    }
+);
+
+impl_instance!(USART6, usart_peripheral: USART6, usart_crate: usart6,
+    flexcomm: {
+        field: FLEXCOMM6,
+        clock_field: fc6
+    },
+
+    reset: {
+        bit: fc6_rst
+    },
+
+    clock: {
+        sel_field: fcclksel6,
+        frg_field: flexfrg6ctrl
+    },
+
+    pins: {
+        tx: pio1_16 => 2,
+        rx: pio1_13 => 2
+    }
+);
+
+impl_instance!(USART7, usart_peripheral: USART7, usart_crate: usart7,
+    flexcomm: {
+        field: FLEXCOMM7,
+        clock_field: fc7
+    },
+
+    reset: {
+        bit: fc7_rst
+    },
+
+    clock: {
+        sel_field: fcclksel7,
+        frg_field: flexfrg7ctrl
+    },
+
+    pins: {
+        tx: pio0_19 => 7,
+        rx: pio0_20 => 7
+    }
+);
+
+/// Trait for TX pins.
+pub trait TxPin<T: Instance>: crate::gpio::Pin {}
+/// Trait for RX pins.
+pub trait RxPin<T: Instance>: crate::gpio::Pin {}
+
+// TODO: Add RTS, CTS and CLK pin traits
+
+macro_rules! impl_pin {
+    ($pin:ident, $instance:ident, Tx) => {
+        impl TxPin<crate::peripherals::$instance> for crate::peripherals::$pin {}
+    };
+    ($pin:ident, $instance:ident, Rx) => {
+        impl RxPin<crate::peripherals::$instance> for crate::peripherals::$pin {}
+    };
+}
+
+impl_pin!(PIO1_5, USART0, Rx);
+impl_pin!(PIO1_6, USART0, Tx);
+impl_pin!(PIO1_10, USART1, Rx);
+impl_pin!(PIO1_11, USART1, Tx);
+impl_pin!(PIO0_27, USART2, Tx);
+impl_pin!(PIO1_24, USART2, Rx);
+impl_pin!(PIO0_2, USART3, Tx);
+impl_pin!(PIO0_3, USART3, Rx);
+impl_pin!(PIO0_16, USART4, Tx);
+impl_pin!(PIO0_5, USART4, Rx);
+impl_pin!(PIO0_8, USART5, Rx);
+impl_pin!(PIO0_9, USART5, Tx);
+impl_pin!(PIO1_16, USART6, Tx);
+impl_pin!(PIO1_13, USART6, Rx);
+impl_pin!(PIO0_20, USART7, Rx);
+impl_pin!(PIO0_19, USART7, Tx);
+
+/// Get the SYSCON register block.
+///
+/// # Safety
+/// Read/Write operations on a single registers are NOT atomic. You must ensure that the GPIO
+/// registers are not accessed concurrently by multiple threads.
+pub(crate) fn syscon_reg() -> &'static crate::pac::syscon::RegisterBlock {
+    unsafe { &*crate::pac::SYSCON::ptr() }
+}
+
+/// Get the IOCON register block.
+///
+/// # Safety
+/// Read/Write operations on a single registers are NOT atomic. You must ensure that the GPIO
+/// registers are not accessed concurrently by multiple threads.
+pub(crate) fn iocon_reg() -> &'static crate::pac::iocon::RegisterBlock {
+    unsafe { &*crate::pac::IOCON::ptr() }
+}
diff --git a/examples/lpc55s69/src/bin/usart_blocking.rs b/examples/lpc55s69/src/bin/usart_blocking.rs
new file mode 100644
index 000000000..a38ec0c5b
--- /dev/null
+++ b/examples/lpc55s69/src/bin/usart_blocking.rs
@@ -0,0 +1,40 @@
+#![no_std]
+#![no_main]
+
+use core::str::from_utf8_mut;
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_nxp::usart::{Config, Usart};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_halt as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_nxp::init(Default::default());
+    let mut usart = Usart::new_blocking(p.USART2, p.PIO0_27, p.PIO1_24, Config::default());
+    let tx_buf = b"Hello, Ferris!";
+    let mut rx_buf = [0u8; 14];
+
+    loop {
+        info!("Write a message");
+        usart.blocking_write(tx_buf).unwrap();
+        usart.blocking_flush().unwrap();
+
+        Timer::after_millis(500).await;
+
+        info!("Read a message");
+        usart.blocking_read(&mut rx_buf).unwrap();
+
+        match from_utf8_mut(&mut rx_buf) {
+            Ok(str) => {
+                info!("The message is: {}", str);
+            }
+            Err(_) => {
+                error!("Error in converting to UTF8");
+            }
+        }
+
+        Timer::after_millis(500).await;
+    }
+}