diff --git a/Cargo.toml b/Cargo.toml
index 5ba9ba7d..3e036b61 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,9 @@
 members = [
     "embassy",
     "embassy-nrf",
+    "embassy-stm32f4",
     "embassy-nrf-examples",
+    "embassy-stm32f4-examples",
     "embassy-macros",
 ]
 
diff --git a/embassy-stm32f4-examples/Cargo.toml b/embassy-stm32f4-examples/Cargo.toml
new file mode 100644
index 00000000..6502a77a
--- /dev/null
+++ b/embassy-stm32f4-examples/Cargo.toml
@@ -0,0 +1,39 @@
+[package]
+authors = ["Dario Nieuwenhuis <dirbaio@dirbaio.net>"]
+edition = "2018"
+name = "embassy-stm32f4-examples"
+version = "0.1.0"
+
+[features]
+default = [
+    "defmt-default",
+]
+defmt-default = []
+defmt-trace = []
+defmt-debug = []
+defmt-info = []
+defmt-warn = []
+defmt-error = []
+
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../embassy", features = ["defmt", "defmt-trace"] }
+embassy-stm32f4 = { version = "*", path = "../embassy-stm32f4", features = ["stm32f405"] }
+
+defmt = "0.1.3"
+defmt-rtt = "0.1.0"
+
+cortex-m        = { version = "0.6.3" }
+cortex-m-rt = "0.6.13"
+embedded-hal    = { version = "0.2.4" }
+panic-probe = "0.1.0"
+stm32f4xx-hal  = { version = "0.8.3", features = ["rt", "stm32f405"], git = "https://github.com/stm32-rs/stm32f4xx-hal.git"}
+futures = { version = "0.3.8", default-features = false, features = ["async-await"] }
+cortex-m-rtic = "0.5"
+rtt-target = { version = "0.3", features = ["cortex-m"] }
+
+
+
+[[bin]]
+name = "serial"
+path = "src/serial.rs"
\ No newline at end of file
diff --git a/embassy-stm32f4-examples/src/serial.rs b/embassy-stm32f4-examples/src/serial.rs
new file mode 100644
index 00000000..baed2e52
--- /dev/null
+++ b/embassy-stm32f4-examples/src/serial.rs
@@ -0,0 +1,64 @@
+#![no_std]
+#![no_main]
+#![feature(trait_alias)]
+#![feature(type_alias_impl_trait)]
+
+// extern crate panic_halt;
+
+use cortex_m::singleton;
+use cortex_m_rt::entry;
+use embassy::executor::{task, Executor};
+use embassy::util::Forever;
+use embassy_stm32f4::interrupt;
+use embassy_stm32f4::serial;
+use stm32f4xx_hal::stm32;
+use stm32f4xx_hal::{prelude::*, serial::config};
+
+#[task]
+async fn run(dp: stm32::Peripherals, cp: cortex_m::Peripherals) {
+    // https://gist.github.com/thalesfragoso/a07340c5df6eee3b04c42fdc69ecdcb1
+    let gpioa = dp.GPIOA.split();
+    let rcc = dp.RCC.constrain();
+
+    let clocks = rcc
+        .cfgr
+        .use_hse(16.mhz())
+        .sysclk(48.mhz())
+        .pclk1(24.mhz())
+        .freeze();
+
+    let mut serial = serial::Serial::new(
+        gpioa.pa9.into_alternate_af7(),
+        gpioa.pa10.into_alternate_af7(),
+        interrupt::take!(DMA2_STREAM7),
+        interrupt::take!(DMA2_STREAM2),
+        interrupt::take!(USART1),
+        dp.DMA2,
+        dp.USART1,
+        config::Parity::ParityNone,
+        9600.bps(),
+        clocks,
+    );
+
+    let buf = singleton!(: [u8; 30] = [0; 30]).unwrap();
+
+    buf[5] = 0x01;
+
+    serial.send(buf).await;
+}
+
+static EXECUTOR: Forever<Executor> = Forever::new();
+
+#[entry]
+fn main() -> ! {
+    let dp = stm32::Peripherals::take().unwrap();
+    let cp = cortex_m::peripheral::Peripherals::take().unwrap();
+
+    let executor = EXECUTOR.put(Executor::new(cortex_m::asm::sev));
+    executor.spawn(run(dp, cp));
+
+    loop {
+        executor.run();
+        cortex_m::asm::wfe();
+    }
+}
diff --git a/embassy-stm32f4/Cargo.toml b/embassy-stm32f4/Cargo.toml
new file mode 100644
index 00000000..44cf3db9
--- /dev/null
+++ b/embassy-stm32f4/Cargo.toml
@@ -0,0 +1,43 @@
+[package]
+name = "embassy-stm32f4"
+version = "0.1.0"
+authors = ["Dario Nieuwenhuis <dirbaio@dirbaio.net>"]
+edition = "2018"
+
+[features]
+defmt-trace = [ ]
+defmt-debug = [ ]
+defmt-info = [ ]
+defmt-warn = [ ]
+defmt-error = [ ]
+
+stm32f401 = ["stm32f4xx-hal/stm32f401"]
+stm32f405 = ["stm32f4xx-hal/stm32f405"]
+stm32f407 = ["stm32f4xx-hal/stm32f407"]
+stm32f410 = ["stm32f4xx-hal/stm32f410"]
+stm32f411 = ["stm32f4xx-hal/stm32f411"]
+stm32f412 = ["stm32f4xx-hal/stm32f412"]
+stm32f413 = ["stm32f4xx-hal/stm32f413"]
+stm32f415 = ["stm32f4xx-hal/stm32f405"]
+stm32f417 = ["stm32f4xx-hal/stm32f407"]
+stm32f423 = ["stm32f4xx-hal/stm32f413"]
+stm32f427 = ["stm32f4xx-hal/stm32f427"]
+stm32f429 = ["stm32f4xx-hal/stm32f429"]
+stm32f437 = ["stm32f4xx-hal/stm32f427"]
+stm32f439 = ["stm32f4xx-hal/stm32f429"]
+stm32f446 = ["stm32f4xx-hal/stm32f446"]
+stm32f469 = ["stm32f4xx-hal/stm32f469"]
+stm32f479 = ["stm32f4xx-hal/stm32f469"]
+
+default = ["stm32f405"]
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../embassy" }
+
+defmt = { version = "0.1.3", optional = true }
+log = { version = "0.4.11", optional = true }
+cortex-m-rt = "0.6.13"
+cortex-m        = { version = "0.6.4" }
+embedded-hal    = { version = "0.2.4" }
+embedded-dma    = { version = "0.1.2" }
+stm32f4xx-hal  = { version = "0.8.3", features = ["rt"], git = "https://github.com/stm32-rs/stm32f4xx-hal.git"}
diff --git a/embassy-stm32f4/src/fmt.rs b/embassy-stm32f4/src/fmt.rs
new file mode 100644
index 00000000..4da69766
--- /dev/null
+++ b/embassy-stm32f4/src/fmt.rs
@@ -0,0 +1,118 @@
+#![macro_use]
+
+#[cfg(all(feature = "defmt", feature = "log"))]
+compile_error!("You may not enable both `defmt` and `log` features.");
+
+pub use fmt::*;
+
+#[cfg(feature = "defmt")]
+mod fmt {
+    pub use defmt::{
+        assert, assert_eq, assert_ne, debug, debug_assert, debug_assert_eq, debug_assert_ne, error,
+        info, panic, todo, trace, unreachable, unwrap, warn,
+    };
+}
+
+#[cfg(feature = "log")]
+mod fmt {
+    pub use core::{
+        assert, assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, panic, todo,
+        unreachable,
+    };
+    pub use log::{debug, error, info, trace, warn};
+}
+
+#[cfg(not(any(feature = "defmt", feature = "log")))]
+mod fmt {
+    #![macro_use]
+
+    pub use core::{
+        assert, assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, panic, todo,
+        unreachable,
+    };
+
+    #[macro_export]
+    macro_rules! trace {
+        ($($msg:expr),+ $(,)?) => {
+            ()
+        };
+    }
+
+    #[macro_export]
+    macro_rules! debug {
+        ($($msg:expr),+ $(,)?) => {
+            ()
+        };
+    }
+
+    #[macro_export]
+    macro_rules! info {
+        ($($msg:expr),+ $(,)?) => {
+            ()
+        };
+    }
+
+    #[macro_export]
+    macro_rules! warn {
+        ($($msg:expr),+ $(,)?) => {
+            ()
+        };
+    }
+
+    #[macro_export]
+    macro_rules! error {
+        ($($msg:expr),+ $(,)?) => {
+            ()
+        };
+    }
+}
+
+#[cfg(not(feature = "defmt"))]
+#[macro_export]
+macro_rules! unwrap {
+    ($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
+    }
+}
diff --git a/embassy-stm32f4/src/interrupt.rs b/embassy-stm32f4/src/interrupt.rs
new file mode 100644
index 00000000..502d666e
--- /dev/null
+++ b/embassy-stm32f4/src/interrupt.rs
@@ -0,0 +1,193 @@
+//! Interrupt management
+//!
+//! This module implements an API for managing interrupts compatible with
+//! nrf_softdevice::interrupt. Intended for switching between the two at compile-time.
+
+use core::sync::atomic::{compiler_fence, Ordering};
+
+use crate::pac::NVIC_PRIO_BITS;
+
+// Re-exports
+pub use crate::pac::Interrupt;
+pub use crate::pac::Interrupt::*; // needed for cortex-m-rt #[interrupt]
+pub use cortex_m::interrupt::{CriticalSection, Mutex};
+pub use embassy::interrupt::{declare, take, OwnedInterrupt};
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum Priority {
+    Level0 = 0,
+    Level1 = 1,
+    Level2 = 2,
+    Level3 = 3,
+    Level4 = 4,
+    Level5 = 5,
+    Level6 = 6,
+    Level7 = 7,
+    Level8 = 8,
+    Level9 = 9,
+    Level10 = 10,
+    Level11 = 11,
+    Level12 = 12,
+    Level13 = 13,
+    Level14 = 14,
+    Level15 = 15,
+}
+
+impl From<u8> for Priority {
+    fn from(priority: u8) -> Self {
+        match priority >> (8 - NVIC_PRIO_BITS) {
+            0 => Self::Level0,
+            1 => Self::Level1,
+            2 => Self::Level2,
+            3 => Self::Level3,
+            4 => Self::Level4,
+            5 => Self::Level5,
+            6 => Self::Level6,
+            7 => Self::Level7,
+            8 => Self::Level8,
+            9 => Self::Level9,
+            10 => Self::Level10,
+            11 => Self::Level11,
+            12 => Self::Level12,
+            13 => Self::Level13,
+            14 => Self::Level14,
+            15 => Self::Level15,
+            _ => unreachable!(),
+        }
+    }
+}
+
+impl From<Priority> for u8 {
+    fn from(p: Priority) -> Self {
+        (p as u8) << (8 - NVIC_PRIO_BITS)
+    }
+}
+
+#[inline]
+pub fn free<F, R>(f: F) -> R
+where
+    F: FnOnce(&CriticalSection) -> R,
+{
+    unsafe {
+        // TODO: assert that we're in privileged level
+        // Needed because disabling irqs in non-privileged level is a noop, which would break safety.
+
+        let primask: u32;
+        asm!("mrs {}, PRIMASK", out(reg) primask);
+
+        asm!("cpsid i");
+
+        // Prevent compiler from reordering operations inside/outside the critical section.
+        compiler_fence(Ordering::SeqCst);
+
+        let r = f(&CriticalSection::new());
+
+        compiler_fence(Ordering::SeqCst);
+
+        if primask & 1 == 0 {
+            asm!("cpsie i");
+        }
+
+        r
+    }
+}
+
+#[cfg(feature = "stm32f405")]
+mod irqs {
+    use super::*;
+    declare!(WWDG);
+    declare!(PVD);
+    declare!(TAMP_STAMP);
+    declare!(RTC_WKUP);
+    //    declare!(FLASH);
+    declare!(RCC);
+    declare!(EXTI0);
+    declare!(EXTI1);
+    declare!(EXTI2);
+    declare!(EXTI3);
+    declare!(EXTI4);
+    declare!(DMA1_STREAM0);
+    declare!(DMA1_STREAM1);
+    declare!(DMA1_STREAM2);
+    declare!(DMA1_STREAM3);
+    declare!(DMA1_STREAM4);
+    declare!(DMA1_STREAM5);
+    declare!(DMA1_STREAM6);
+    declare!(ADC);
+    declare!(CAN1_TX);
+    declare!(CAN1_RX0);
+    declare!(CAN1_RX1);
+    declare!(CAN1_SCE);
+    declare!(EXTI9_5);
+    declare!(TIM1_BRK_TIM9);
+    declare!(TIM1_UP_TIM10);
+    declare!(TIM1_TRG_COM_TIM11);
+    declare!(TIM1_CC);
+    declare!(TIM2);
+    declare!(TIM3);
+    declare!(TIM4);
+    declare!(I2C1_EV);
+    declare!(I2C1_ER);
+    declare!(I2C2_EV);
+    declare!(I2C2_ER);
+    declare!(SPI1);
+    declare!(SPI2);
+    declare!(USART1);
+    declare!(USART2);
+    declare!(USART3);
+    declare!(EXTI15_10);
+    declare!(RTC_ALARM);
+    declare!(OTG_FS_WKUP);
+    declare!(TIM8_BRK_TIM12);
+    declare!(TIM8_UP_TIM13);
+    declare!(TIM8_TRG_COM_TIM14);
+    declare!(TIM8_CC);
+    declare!(DMA1_STREAM7);
+    //    declare!(FMC);
+    declare!(SDIO);
+    declare!(TIM5);
+    declare!(SPI3);
+    declare!(UART4);
+    declare!(UART5);
+    declare!(TIM6_DAC);
+    declare!(TIM7);
+    declare!(DMA2_STREAM0);
+    declare!(DMA2_STREAM1);
+    declare!(DMA2_STREAM2);
+    declare!(DMA2_STREAM3);
+    declare!(DMA2_STREAM4);
+    declare!(ETH);
+    declare!(ETH_WKUP);
+    declare!(CAN2_TX);
+    declare!(CAN2_RX0);
+    declare!(CAN2_RX1);
+    declare!(CAN2_SCE);
+    declare!(OTG_FS);
+    declare!(DMA2_STREAM5);
+    declare!(DMA2_STREAM6);
+    declare!(DMA2_STREAM7);
+    declare!(USART6);
+    declare!(I2C3_EV);
+    declare!(I2C3_ER);
+    declare!(OTG_HS_EP1_OUT);
+    declare!(OTG_HS_EP1_IN);
+    declare!(OTG_HS_WKUP);
+    declare!(OTG_HS);
+    declare!(DCMI);
+    declare!(CRYP);
+    declare!(HASH_RNG);
+    declare!(FPU);
+    //    declare!(UART7);
+    //    declare!(UART8);
+    //    declare!(SPI4);
+    //    declare!(SPI5);
+    //    declare!(SPI6);
+    //    declare!(SAI1);
+    declare!(LCD_TFT);
+    declare!(LCD_TFT_1);
+    //    declare!(DMA2D);
+}
+
+pub use irqs::*;
diff --git a/embassy-stm32f4/src/lib.rs b/embassy-stm32f4/src/lib.rs
new file mode 100644
index 00000000..0f4a70bb
--- /dev/null
+++ b/embassy-stm32f4/src/lib.rs
@@ -0,0 +1,317 @@
+#![no_std]
+#![feature(generic_associated_types)]
+#![feature(asm)]
+#![feature(type_alias_impl_trait)]
+#![feature(let_chains)]
+
+#[cfg(not(any(
+    feature = "stm32f401",
+    feature = "stm32f405",
+    feature = "stm32f407",
+    feature = "stm32f410",
+    feature = "stm32f411",
+    feature = "stm32f412",
+    feature = "stm32f413",
+    feature = "stm32f415",
+    feature = "stm32f417",
+    feature = "stm32f423",
+    feature = "stm32f427",
+    feature = "stm32f429",
+    feature = "stm32f437",
+    feature = "stm32f439",
+    feature = "stm32f446",
+    feature = "stm32f469",
+    feature = "stm32f479",
+)))]
+compile_error!(
+    "No chip feature activated. You must activate exactly one of the following features: "
+);
+
+#[cfg(any(
+    all(feature = "stm32f401", feature = "stm32f405"),
+    all(feature = "stm32f401", feature = "stm32f407"),
+    all(feature = "stm32f401", feature = "stm32f410"),
+    all(feature = "stm32f401", feature = "stm32f411"),
+    all(feature = "stm32f401", feature = "stm32f412"),
+    all(feature = "stm32f401", feature = "stm32f413"),
+    all(feature = "stm32f401", feature = "stm32f415"),
+    all(feature = "stm32f401", feature = "stm32f417"),
+    all(feature = "stm32f401", feature = "stm32f423"),
+    all(feature = "stm32f401", feature = "stm32f427"),
+    all(feature = "stm32f401", feature = "stm32f429"),
+    all(feature = "stm32f401", feature = "stm32f437"),
+    all(feature = "stm32f401", feature = "stm32f439"),
+    all(feature = "stm32f401", feature = "stm32f446"),
+    all(feature = "stm32f401", feature = "stm32f469"),
+    all(feature = "stm32f401", feature = "stm32f479"),
+    all(feature = "stm32f405", feature = "stm32f401"),
+    all(feature = "stm32f405", feature = "stm32f407"),
+    all(feature = "stm32f405", feature = "stm32f410"),
+    all(feature = "stm32f405", feature = "stm32f411"),
+    all(feature = "stm32f405", feature = "stm32f412"),
+    all(feature = "stm32f405", feature = "stm32f413"),
+    all(feature = "stm32f405", feature = "stm32f415"),
+    all(feature = "stm32f405", feature = "stm32f417"),
+    all(feature = "stm32f405", feature = "stm32f423"),
+    all(feature = "stm32f405", feature = "stm32f427"),
+    all(feature = "stm32f405", feature = "stm32f429"),
+    all(feature = "stm32f405", feature = "stm32f437"),
+    all(feature = "stm32f405", feature = "stm32f439"),
+    all(feature = "stm32f405", feature = "stm32f446"),
+    all(feature = "stm32f405", feature = "stm32f469"),
+    all(feature = "stm32f405", feature = "stm32f479"),
+    all(feature = "stm32f407", feature = "stm32f401"),
+    all(feature = "stm32f407", feature = "stm32f405"),
+    all(feature = "stm32f407", feature = "stm32f410"),
+    all(feature = "stm32f407", feature = "stm32f411"),
+    all(feature = "stm32f407", feature = "stm32f412"),
+    all(feature = "stm32f407", feature = "stm32f413"),
+    all(feature = "stm32f407", feature = "stm32f415"),
+    all(feature = "stm32f407", feature = "stm32f417"),
+    all(feature = "stm32f407", feature = "stm32f423"),
+    all(feature = "stm32f407", feature = "stm32f427"),
+    all(feature = "stm32f407", feature = "stm32f429"),
+    all(feature = "stm32f407", feature = "stm32f437"),
+    all(feature = "stm32f407", feature = "stm32f439"),
+    all(feature = "stm32f407", feature = "stm32f446"),
+    all(feature = "stm32f407", feature = "stm32f469"),
+    all(feature = "stm32f407", feature = "stm32f479"),
+    all(feature = "stm32f410", feature = "stm32f401"),
+    all(feature = "stm32f410", feature = "stm32f405"),
+    all(feature = "stm32f410", feature = "stm32f407"),
+    all(feature = "stm32f410", feature = "stm32f411"),
+    all(feature = "stm32f410", feature = "stm32f412"),
+    all(feature = "stm32f410", feature = "stm32f413"),
+    all(feature = "stm32f410", feature = "stm32f415"),
+    all(feature = "stm32f410", feature = "stm32f417"),
+    all(feature = "stm32f410", feature = "stm32f423"),
+    all(feature = "stm32f410", feature = "stm32f427"),
+    all(feature = "stm32f410", feature = "stm32f429"),
+    all(feature = "stm32f410", feature = "stm32f437"),
+    all(feature = "stm32f410", feature = "stm32f439"),
+    all(feature = "stm32f410", feature = "stm32f446"),
+    all(feature = "stm32f410", feature = "stm32f469"),
+    all(feature = "stm32f410", feature = "stm32f479"),
+    all(feature = "stm32f411", feature = "stm32f401"),
+    all(feature = "stm32f411", feature = "stm32f405"),
+    all(feature = "stm32f411", feature = "stm32f407"),
+    all(feature = "stm32f411", feature = "stm32f410"),
+    all(feature = "stm32f411", feature = "stm32f412"),
+    all(feature = "stm32f411", feature = "stm32f413"),
+    all(feature = "stm32f411", feature = "stm32f415"),
+    all(feature = "stm32f411", feature = "stm32f417"),
+    all(feature = "stm32f411", feature = "stm32f423"),
+    all(feature = "stm32f411", feature = "stm32f427"),
+    all(feature = "stm32f411", feature = "stm32f429"),
+    all(feature = "stm32f411", feature = "stm32f437"),
+    all(feature = "stm32f411", feature = "stm32f439"),
+    all(feature = "stm32f411", feature = "stm32f446"),
+    all(feature = "stm32f411", feature = "stm32f469"),
+    all(feature = "stm32f411", feature = "stm32f479"),
+    all(feature = "stm32f412", feature = "stm32f401"),
+    all(feature = "stm32f412", feature = "stm32f405"),
+    all(feature = "stm32f412", feature = "stm32f407"),
+    all(feature = "stm32f412", feature = "stm32f410"),
+    all(feature = "stm32f412", feature = "stm32f411"),
+    all(feature = "stm32f412", feature = "stm32f413"),
+    all(feature = "stm32f412", feature = "stm32f415"),
+    all(feature = "stm32f412", feature = "stm32f417"),
+    all(feature = "stm32f412", feature = "stm32f423"),
+    all(feature = "stm32f412", feature = "stm32f427"),
+    all(feature = "stm32f412", feature = "stm32f429"),
+    all(feature = "stm32f412", feature = "stm32f437"),
+    all(feature = "stm32f412", feature = "stm32f439"),
+    all(feature = "stm32f412", feature = "stm32f446"),
+    all(feature = "stm32f412", feature = "stm32f469"),
+    all(feature = "stm32f412", feature = "stm32f479"),
+    all(feature = "stm32f413", feature = "stm32f401"),
+    all(feature = "stm32f413", feature = "stm32f405"),
+    all(feature = "stm32f413", feature = "stm32f407"),
+    all(feature = "stm32f413", feature = "stm32f410"),
+    all(feature = "stm32f413", feature = "stm32f411"),
+    all(feature = "stm32f413", feature = "stm32f412"),
+    all(feature = "stm32f413", feature = "stm32f415"),
+    all(feature = "stm32f413", feature = "stm32f417"),
+    all(feature = "stm32f413", feature = "stm32f423"),
+    all(feature = "stm32f413", feature = "stm32f427"),
+    all(feature = "stm32f413", feature = "stm32f429"),
+    all(feature = "stm32f413", feature = "stm32f437"),
+    all(feature = "stm32f413", feature = "stm32f439"),
+    all(feature = "stm32f413", feature = "stm32f446"),
+    all(feature = "stm32f413", feature = "stm32f469"),
+    all(feature = "stm32f413", feature = "stm32f479"),
+    all(feature = "stm32f415", feature = "stm32f401"),
+    all(feature = "stm32f415", feature = "stm32f405"),
+    all(feature = "stm32f415", feature = "stm32f407"),
+    all(feature = "stm32f415", feature = "stm32f410"),
+    all(feature = "stm32f415", feature = "stm32f411"),
+    all(feature = "stm32f415", feature = "stm32f412"),
+    all(feature = "stm32f415", feature = "stm32f413"),
+    all(feature = "stm32f415", feature = "stm32f417"),
+    all(feature = "stm32f415", feature = "stm32f423"),
+    all(feature = "stm32f415", feature = "stm32f427"),
+    all(feature = "stm32f415", feature = "stm32f429"),
+    all(feature = "stm32f415", feature = "stm32f437"),
+    all(feature = "stm32f415", feature = "stm32f439"),
+    all(feature = "stm32f415", feature = "stm32f446"),
+    all(feature = "stm32f415", feature = "stm32f469"),
+    all(feature = "stm32f415", feature = "stm32f479"),
+    all(feature = "stm32f417", feature = "stm32f401"),
+    all(feature = "stm32f417", feature = "stm32f405"),
+    all(feature = "stm32f417", feature = "stm32f407"),
+    all(feature = "stm32f417", feature = "stm32f410"),
+    all(feature = "stm32f417", feature = "stm32f411"),
+    all(feature = "stm32f417", feature = "stm32f412"),
+    all(feature = "stm32f417", feature = "stm32f413"),
+    all(feature = "stm32f417", feature = "stm32f415"),
+    all(feature = "stm32f417", feature = "stm32f423"),
+    all(feature = "stm32f417", feature = "stm32f427"),
+    all(feature = "stm32f417", feature = "stm32f429"),
+    all(feature = "stm32f417", feature = "stm32f437"),
+    all(feature = "stm32f417", feature = "stm32f439"),
+    all(feature = "stm32f417", feature = "stm32f446"),
+    all(feature = "stm32f417", feature = "stm32f469"),
+    all(feature = "stm32f417", feature = "stm32f479"),
+    all(feature = "stm32f423", feature = "stm32f401"),
+    all(feature = "stm32f423", feature = "stm32f405"),
+    all(feature = "stm32f423", feature = "stm32f407"),
+    all(feature = "stm32f423", feature = "stm32f410"),
+    all(feature = "stm32f423", feature = "stm32f411"),
+    all(feature = "stm32f423", feature = "stm32f412"),
+    all(feature = "stm32f423", feature = "stm32f413"),
+    all(feature = "stm32f423", feature = "stm32f415"),
+    all(feature = "stm32f423", feature = "stm32f417"),
+    all(feature = "stm32f423", feature = "stm32f427"),
+    all(feature = "stm32f423", feature = "stm32f429"),
+    all(feature = "stm32f423", feature = "stm32f437"),
+    all(feature = "stm32f423", feature = "stm32f439"),
+    all(feature = "stm32f423", feature = "stm32f446"),
+    all(feature = "stm32f423", feature = "stm32f469"),
+    all(feature = "stm32f423", feature = "stm32f479"),
+    all(feature = "stm32f427", feature = "stm32f401"),
+    all(feature = "stm32f427", feature = "stm32f405"),
+    all(feature = "stm32f427", feature = "stm32f407"),
+    all(feature = "stm32f427", feature = "stm32f410"),
+    all(feature = "stm32f427", feature = "stm32f411"),
+    all(feature = "stm32f427", feature = "stm32f412"),
+    all(feature = "stm32f427", feature = "stm32f413"),
+    all(feature = "stm32f427", feature = "stm32f415"),
+    all(feature = "stm32f427", feature = "stm32f417"),
+    all(feature = "stm32f427", feature = "stm32f423"),
+    all(feature = "stm32f427", feature = "stm32f429"),
+    all(feature = "stm32f427", feature = "stm32f437"),
+    all(feature = "stm32f427", feature = "stm32f439"),
+    all(feature = "stm32f427", feature = "stm32f446"),
+    all(feature = "stm32f427", feature = "stm32f469"),
+    all(feature = "stm32f427", feature = "stm32f479"),
+    all(feature = "stm32f429", feature = "stm32f401"),
+    all(feature = "stm32f429", feature = "stm32f405"),
+    all(feature = "stm32f429", feature = "stm32f407"),
+    all(feature = "stm32f429", feature = "stm32f410"),
+    all(feature = "stm32f429", feature = "stm32f411"),
+    all(feature = "stm32f429", feature = "stm32f412"),
+    all(feature = "stm32f429", feature = "stm32f413"),
+    all(feature = "stm32f429", feature = "stm32f415"),
+    all(feature = "stm32f429", feature = "stm32f417"),
+    all(feature = "stm32f429", feature = "stm32f423"),
+    all(feature = "stm32f429", feature = "stm32f427"),
+    all(feature = "stm32f429", feature = "stm32f437"),
+    all(feature = "stm32f429", feature = "stm32f439"),
+    all(feature = "stm32f429", feature = "stm32f446"),
+    all(feature = "stm32f429", feature = "stm32f469"),
+    all(feature = "stm32f429", feature = "stm32f479"),
+    all(feature = "stm32f437", feature = "stm32f401"),
+    all(feature = "stm32f437", feature = "stm32f405"),
+    all(feature = "stm32f437", feature = "stm32f407"),
+    all(feature = "stm32f437", feature = "stm32f410"),
+    all(feature = "stm32f437", feature = "stm32f411"),
+    all(feature = "stm32f437", feature = "stm32f412"),
+    all(feature = "stm32f437", feature = "stm32f413"),
+    all(feature = "stm32f437", feature = "stm32f415"),
+    all(feature = "stm32f437", feature = "stm32f417"),
+    all(feature = "stm32f437", feature = "stm32f423"),
+    all(feature = "stm32f437", feature = "stm32f427"),
+    all(feature = "stm32f437", feature = "stm32f429"),
+    all(feature = "stm32f437", feature = "stm32f439"),
+    all(feature = "stm32f437", feature = "stm32f446"),
+    all(feature = "stm32f437", feature = "stm32f469"),
+    all(feature = "stm32f437", feature = "stm32f479"),
+    all(feature = "stm32f439", feature = "stm32f401"),
+    all(feature = "stm32f439", feature = "stm32f405"),
+    all(feature = "stm32f439", feature = "stm32f407"),
+    all(feature = "stm32f439", feature = "stm32f410"),
+    all(feature = "stm32f439", feature = "stm32f411"),
+    all(feature = "stm32f439", feature = "stm32f412"),
+    all(feature = "stm32f439", feature = "stm32f413"),
+    all(feature = "stm32f439", feature = "stm32f415"),
+    all(feature = "stm32f439", feature = "stm32f417"),
+    all(feature = "stm32f439", feature = "stm32f423"),
+    all(feature = "stm32f439", feature = "stm32f427"),
+    all(feature = "stm32f439", feature = "stm32f429"),
+    all(feature = "stm32f439", feature = "stm32f437"),
+    all(feature = "stm32f439", feature = "stm32f446"),
+    all(feature = "stm32f439", feature = "stm32f469"),
+    all(feature = "stm32f439", feature = "stm32f479"),
+    all(feature = "stm32f446", feature = "stm32f401"),
+    all(feature = "stm32f446", feature = "stm32f405"),
+    all(feature = "stm32f446", feature = "stm32f407"),
+    all(feature = "stm32f446", feature = "stm32f410"),
+    all(feature = "stm32f446", feature = "stm32f411"),
+    all(feature = "stm32f446", feature = "stm32f412"),
+    all(feature = "stm32f446", feature = "stm32f413"),
+    all(feature = "stm32f446", feature = "stm32f415"),
+    all(feature = "stm32f446", feature = "stm32f417"),
+    all(feature = "stm32f446", feature = "stm32f423"),
+    all(feature = "stm32f446", feature = "stm32f427"),
+    all(feature = "stm32f446", feature = "stm32f429"),
+    all(feature = "stm32f446", feature = "stm32f437"),
+    all(feature = "stm32f446", feature = "stm32f439"),
+    all(feature = "stm32f446", feature = "stm32f469"),
+    all(feature = "stm32f446", feature = "stm32f479"),
+    all(feature = "stm32f469", feature = "stm32f401"),
+    all(feature = "stm32f469", feature = "stm32f405"),
+    all(feature = "stm32f469", feature = "stm32f407"),
+    all(feature = "stm32f469", feature = "stm32f410"),
+    all(feature = "stm32f469", feature = "stm32f411"),
+    all(feature = "stm32f469", feature = "stm32f412"),
+    all(feature = "stm32f469", feature = "stm32f413"),
+    all(feature = "stm32f469", feature = "stm32f415"),
+    all(feature = "stm32f469", feature = "stm32f417"),
+    all(feature = "stm32f469", feature = "stm32f423"),
+    all(feature = "stm32f469", feature = "stm32f427"),
+    all(feature = "stm32f469", feature = "stm32f429"),
+    all(feature = "stm32f469", feature = "stm32f437"),
+    all(feature = "stm32f469", feature = "stm32f439"),
+    all(feature = "stm32f469", feature = "stm32f446"),
+    all(feature = "stm32f469", feature = "stm32f479"),
+    all(feature = "stm32f479", feature = "stm32f401"),
+    all(feature = "stm32f479", feature = "stm32f405"),
+    all(feature = "stm32f479", feature = "stm32f407"),
+    all(feature = "stm32f479", feature = "stm32f410"),
+    all(feature = "stm32f479", feature = "stm32f411"),
+    all(feature = "stm32f479", feature = "stm32f412"),
+    all(feature = "stm32f479", feature = "stm32f413"),
+    all(feature = "stm32f479", feature = "stm32f415"),
+    all(feature = "stm32f479", feature = "stm32f417"),
+    all(feature = "stm32f479", feature = "stm32f423"),
+    all(feature = "stm32f479", feature = "stm32f427"),
+    all(feature = "stm32f479", feature = "stm32f429"),
+    all(feature = "stm32f479", feature = "stm32f437"),
+    all(feature = "stm32f479", feature = "stm32f439"),
+    all(feature = "stm32f479", feature = "stm32f446"),
+    all(feature = "stm32f479", feature = "stm32f469"),
+))]
+compile_error!(
+    "Multile chip features activated. You must activate exactly one of the following features: "
+);
+
+pub use stm32f4xx_hal as hal;
+pub use stm32f4xx_hal::stm32 as pac;
+
+// This mod MUST go first, so that the others see its macros.
+pub(crate) mod fmt;
+
+pub mod interrupt;
+pub mod serial;
+
+pub use cortex_m_rt::interrupt;
diff --git a/embassy-stm32f4/src/serial.rs b/embassy-stm32f4/src/serial.rs
new file mode 100644
index 00000000..cc55ef32
--- /dev/null
+++ b/embassy-stm32f4/src/serial.rs
@@ -0,0 +1,224 @@
+//! Async low power Serial.
+//!
+//! The peripheral is autmatically enabled and disabled as required to save power.
+//! Lowest power consumption can only be guaranteed if the send receive futures
+//! are dropped correctly (e.g. not using `mem::forget()`).
+
+use core::future::Future;
+use core::ptr;
+use core::sync::atomic::{self, Ordering};
+use core::task::{Context, Poll};
+
+use embassy::interrupt::OwnedInterrupt;
+use embassy::util::Signal;
+use embedded_dma::{StaticReadBuffer, StaticWriteBuffer, WriteBuffer};
+
+use crate::hal::dma::config::DmaConfig;
+use crate::hal::dma::traits::{PeriAddress, Stream};
+use crate::hal::dma::{
+    Channel4, MemoryToPeripheral, PeripheralToMemory, Stream2, Stream7, StreamsTuple, Transfer,
+};
+use crate::hal::gpio::gpioa::{PA10, PA9};
+use crate::hal::gpio::{Alternate, AF7};
+use crate::hal::prelude::*;
+use crate::hal::rcc::Clocks;
+use crate::hal::serial::config::{
+    Config as SerialConfig, DmaConfig as SerialDmaConfig, Parity, StopBits, WordLength,
+};
+use crate::hal::serial::{Event as SerialEvent, Serial as HalSerial};
+use crate::hal::time::Bps;
+
+use crate::interrupt;
+
+use crate::pac::Interrupt;
+use crate::pac::{DMA2, USART1};
+
+/// Interface to the Serial peripheral
+pub struct Serial<USART: PeriAddress<MemSize = u8>, TSTREAM: Stream, RSTREAM: Stream> {
+    tx_stream: Option<TSTREAM>,
+    rx_stream: Option<RSTREAM>,
+    usart: Option<USART>,
+    tx_int: interrupt::DMA2_STREAM7Interrupt,
+    rx_int: interrupt::DMA2_STREAM2Interrupt,
+    usart_int: interrupt::USART1Interrupt,
+}
+
+struct State {
+    tx_int: Signal<()>,
+    rx_int: Signal<()>,
+}
+
+static STATE: State = State {
+    tx_int: Signal::new(),
+    rx_int: Signal::new(),
+};
+
+static mut INSTANCE: *const Serial<USART1, Stream7<DMA2>, Stream2<DMA2>> = ptr::null_mut();
+
+impl Serial<USART1, Stream7<DMA2>, Stream2<DMA2>> {
+    pub fn new(
+        txd: PA9<Alternate<AF7>>,
+        rxd: PA10<Alternate<AF7>>,
+        tx_int: interrupt::DMA2_STREAM7Interrupt,
+        rx_int: interrupt::DMA2_STREAM2Interrupt,
+        usart_int: interrupt::USART1Interrupt,
+        dma: DMA2,
+        usart: USART1,
+        parity: Parity,
+        baudrate: Bps,
+        clocks: Clocks,
+    ) -> Self {
+        let mut serial = HalSerial::usart1(
+            usart,
+            (txd, rxd),
+            SerialConfig {
+                baudrate: baudrate,
+                wordlength: WordLength::DataBits8,
+                parity: Parity::ParityNone,
+                stopbits: StopBits::STOP1,
+                dma: SerialDmaConfig::TxRx,
+            },
+            clocks,
+        )
+        .unwrap();
+
+        serial.listen(SerialEvent::Idle);
+        //        serial.listen(SerialEvent::Txe);
+
+        let (usart, _) = serial.release();
+
+        // Register ISR
+        tx_int.set_handler(Self::on_tx_irq);
+        rx_int.set_handler(Self::on_rx_irq);
+        usart_int.set_handler(Self::on_rx_irq);
+        // usart_int.unpend();
+        // usart_int.enable();
+
+        let streams = StreamsTuple::new(dma);
+
+        Serial {
+            tx_stream: Some(streams.7),
+            rx_stream: Some(streams.2),
+            usart: Some(usart),
+            tx_int: tx_int,
+            rx_int: rx_int,
+            usart_int: usart_int,
+        }
+    }
+
+    unsafe fn on_tx_irq() {
+        let s = &(*INSTANCE);
+
+        s.tx_int.disable();
+
+        STATE.tx_int.signal(());
+    }
+
+    unsafe fn on_rx_irq() {
+        let s = &(*INSTANCE);
+
+        atomic::compiler_fence(Ordering::Acquire);
+        s.rx_int.disable();
+        s.usart_int.disable();
+        atomic::compiler_fence(Ordering::Release);
+
+        STATE.rx_int.signal(());
+    }
+
+    unsafe fn on_usart_irq() {
+        let s = &(*INSTANCE);
+
+        atomic::compiler_fence(Ordering::Acquire);
+        s.rx_int.disable();
+        s.usart_int.disable();
+        atomic::compiler_fence(Ordering::Release);
+
+        STATE.rx_int.signal(());
+    }
+
+    /// Sends serial data.
+    ///
+    /// `tx_buffer` is marked as static as per `embedded-dma` requirements.
+    /// It it safe to use a buffer with a non static lifetime if memory is not
+    /// reused until the future has finished.
+    pub fn send<'a, B: 'a>(&'a mut self, tx_buffer: B) -> impl Future<Output = ()> + 'a
+    where
+        B: StaticWriteBuffer<Word = u8>,
+    {
+        unsafe { INSTANCE = self };
+
+        let tx_stream = self.tx_stream.take().unwrap();
+        let usart = self.usart.take().unwrap();
+        STATE.tx_int.reset();
+
+        async move {
+            let mut tx_transfer = Transfer::init(
+                tx_stream,
+                usart,
+                tx_buffer,
+                None,
+                DmaConfig::default()
+                    .transfer_complete_interrupt(true)
+                    .memory_increment(true)
+                    .double_buffer(false),
+            );
+
+            self.tx_int.unpend();
+            self.tx_int.enable();
+            tx_transfer.start(|_usart| {});
+
+            STATE.tx_int.wait().await;
+
+            let (tx_stream, usart, _buf, _) = tx_transfer.free();
+            self.tx_stream.replace(tx_stream);
+            self.usart.replace(usart);
+        }
+    }
+
+    /// Receives serial data.
+    ///
+    /// The future is pending until the buffer is completely filled.
+    /// A common pattern is to use [`stop()`](ReceiveFuture::stop) to cancel
+    /// unfinished transfers after a timeout to prevent lockup when no more data
+    /// is incoming.
+    ///
+    /// `rx_buffer` is marked as static as per `embedded-dma` requirements.
+    /// It it safe to use a buffer with a non static lifetime if memory is not
+    /// reused until the future has finished.
+    pub fn receive<'a, B: 'a>(&'a mut self, rx_buffer: B) -> impl Future<Output = B> + 'a
+    where
+        B: StaticWriteBuffer<Word = u8> + Unpin,
+    {
+        unsafe { INSTANCE = self };
+
+        let rx_stream = self.rx_stream.take().unwrap();
+        let usart = self.usart.take().unwrap();
+        STATE.rx_int.reset();
+
+        async move {
+            let mut rx_transfer = Transfer::init(
+                rx_stream,
+                usart,
+                rx_buffer,
+                None,
+                DmaConfig::default()
+                    .transfer_complete_interrupt(true)
+                    .memory_increment(true)
+                    .double_buffer(false),
+            );
+
+            self.rx_int.unpend();
+            self.rx_int.enable();
+
+            rx_transfer.start(|_usart| {});
+
+            STATE.rx_int.wait().await;
+
+            let (rx_stream, usart, buf, _) = rx_transfer.free();
+            self.rx_stream.replace(rx_stream);
+            self.usart.replace(usart);
+
+            buf
+        }
+    }
+}