Merge #724

724: STM32 Flash + Bootloader  r=Dirbaio a=lulf

Not working.

Co-authored-by: Ulf Lilleengen <[email protected]>
Co-authored-by: Ulf Lilleengen <[email protected]>

63 files changed, 2118 insertions, 150 deletions

diff --git a/ci.sh b/ci.sh
index 69fa08047..c6fe9c4aa 100755
--- a/ci.sh
+++ b/ci.sh
@@ -58,6 +58,8 @@ cargo batch  \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv8m.main-none-eabihf --features nightly,stm32l552ze,defmt,exti,time-driver-any,unstable-traits \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv6m-none-eabi --features nightly,stm32wl54jc-cm0p,defmt,exti,time-driver-any,unstable-traits \
     --- build --release --manifest-path embassy-stm32/Cargo.toml --target thumbv7em-none-eabi --features nightly,stm32wle5ub,defmt,exti,time-driver-any,unstable-traits \
+    --- build --release --manifest-path embassy-boot/nrf/Cargo.toml --target thumbv7em-none-eabi --features embassy-nrf/nrf52840 \
+    --- build --release --manifest-path embassy-boot/stm32/Cargo.toml --target thumbv7em-none-eabi --features embassy-stm32/stm32wl55jc-cm4 \
     --- build --release --manifest-path docs/modules/ROOT/examples/basic/Cargo.toml --target thumbv7em-none-eabi \
     --- build --release --manifest-path docs/modules/ROOT/examples/layer-by-layer/blinky-pac/Cargo.toml --target thumbv7em-none-eabi \
     --- build --release --manifest-path docs/modules/ROOT/examples/layer-by-layer/blinky-hal/Cargo.toml --target thumbv7em-none-eabi \
@@ -81,6 +83,11 @@ cargo batch  \
     --- build --release --manifest-path examples/stm32u5/Cargo.toml --target thumbv8m.main-none-eabihf --out-dir out/examples/stm32u5 \
     --- build --release --manifest-path examples/stm32wb/Cargo.toml --target thumbv7em-none-eabihf --out-dir out/examples/stm32wb \
     --- build --release --manifest-path examples/stm32wl/Cargo.toml --target thumbv7em-none-eabihf --out-dir out/examples/stm32wl \
+    --- build --release --manifest-path examples/boot/nrf/Cargo.toml --target thumbv7em-none-eabi --out-dir out/examples/boot/nrf --bin b \
+    --- build --release --manifest-path examples/boot/stm32l0/Cargo.toml --target thumbv6m-none-eabi --out-dir out/examples/boot/stm32l0 --bin b \
+    --- build --release --manifest-path examples/boot/stm32l1/Cargo.toml --target thumbv7m-none-eabi --out-dir out/examples/boot/stm32l1 --bin b \
+    --- build --release --manifest-path examples/boot/stm32l4/Cargo.toml --target thumbv7em-none-eabi --out-dir out/examples/boot/stm32l4 --bin b \
+    --- build --release --manifest-path examples/boot/stm32wl/Cargo.toml --target thumbv7em-none-eabihf --out-dir out/examples/boot/stm32wl --bin b \
     --- build --release --manifest-path examples/wasm/Cargo.toml --target wasm32-unknown-unknown --out-dir out/examples/wasm \
     --- build --release --manifest-path tests/stm32/Cargo.toml --target thumbv7m-none-eabi --features stm32f103c8 --out-dir out/tests/bluepill-stm32f103c8 \
     --- build --release --manifest-path tests/stm32/Cargo.toml --target thumbv7em-none-eabi --features stm32f429zi --out-dir out/tests/nucleo-stm32f429zi \
diff --git a/docs/modules/ROOT/nav.adoc b/docs/modules/ROOT/nav.adoc
index 3aa2eb6bc..a45da1958 100644
--- a/docs/modules/ROOT/nav.adoc
+++ b/docs/modules/ROOT/nav.adoc
@@ -3,6 +3,7 @@
 * xref:hal.adoc[Hardware Abstraction Layer]
 ** xref:nrf.adoc[nRF]
 ** xref:stm32.adoc[STM32]
+* xref:bootloader.adoc[Bootloader]
 * xref:getting_started.adoc[Getting started]
 ** xref:basic_application.adoc[Basic application]
 ** xref:layer_by_layer.adoc[Layer by Layer]
diff --git a/docs/modules/ROOT/pages/bootloader.adoc b/docs/modules/ROOT/pages/bootloader.adoc
new file mode 100644
index 000000000..1a984d6dc
--- /dev/null
+++ b/docs/modules/ROOT/pages/bootloader.adoc
@@ -0,0 +1,32 @@
+= Bootloader
+
+`embassy-boot` a lightweight bootloader supporting firmware application upgrades in a power-fail-safe way, with trial boots and rollbacks.
+
+The bootloader can be used either as a library or be flashed directly if you are happy with the default configuration and capabilities.
+
+By design, the bootloader does not provide any network capabilities. Networking capabilities for fetching new firmware can be provided by the user application, using the bootloader as a library for updating the firmware, or by using the bootloader as a library and adding this capability yourself.
+
+The bootloader supports both internal and external flash by relying on the `embedded-storage` traits.
+
+
+== Hardware support
+
+The bootloader supports
+
+* nRF52 with and without softdevice
+* STM32 L4, WB, WL, L1 and L0
+
+In general, the bootloader works on any platform that implements the `embedded-storage` traits for its internal flash, but may require custom initialization code to work.
+
+== Design
+
+The bootloader divides the storage into 4 main partitions, configured by a linker script:
+
+* BOOTLOADER - Where the bootloader is placed. The bootloader itself consumes about 8kB of flash.
+* ACTIVE - Where the main application is placed. The bootloader will attempt to load the application at the start of this partition. This partition is only written to by the bootloader.
+* DFU - Where the application-to-be-swapped is placed. This partition is written to by the application.
+* BOOTLOADER STATE - Where the bootloader stores the current state describing if the active and dfu partitions need to be swapped. When the new firmware has been written to the DFU partition, a flag is set to instruct the bootloader that the partitions should be swapped.
+
+The partitions for ACTIVE (+BOOTLOADER), DFU and BOOTLOADER_STATE may be placed in separate flash, but they have to support compatible page sizes.
+
+The bootloader has a platform-agnostic part, which implements the power fail safe swapping algorithm given the boundaries set by the partitions. The platform-specific part is a minimal shim that provides additional functionality such as watchdogs or supporting the nRF52 softdevice.
diff --git a/embassy-boot/boot/src/lib.rs b/embassy-boot/boot/src/lib.rs
index 0d33ad1a6..554709250 100644
--- a/embassy-boot/boot/src/lib.rs
+++ b/embassy-boot/boot/src/lib.rs
@@ -1,5 +1,7 @@
 #![feature(type_alias_impl_trait)]
 #![feature(generic_associated_types)]
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
 #![no_std]
 ///! embassy-boot is a bootloader and firmware updater for embedded devices with flash
 ///! storage implemented using embedded-storage
@@ -17,8 +19,8 @@ mod fmt;
 use embedded_storage::nor_flash::{NorFlash, NorFlashError, NorFlashErrorKind, ReadNorFlash};
 use embedded_storage_async::nor_flash::AsyncNorFlash;
 
-pub const BOOT_MAGIC: u32 = 0xD00DF00D;
-pub const SWAP_MAGIC: u32 = 0xF00FDAAD;
+const BOOT_MAGIC: u8 = 0xD0;
+const SWAP_MAGIC: u8 = 0xF0;
 
 #[derive(Copy, Clone, Debug)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -80,12 +82,12 @@ pub trait FlashProvider {
 }
 
 /// BootLoader works with any flash implementing embedded_storage and can also work with
-/// different page sizes.
-pub struct BootLoader<const PAGE_SIZE: usize> {
+/// different page sizes and flash write sizes.
+pub struct BootLoader<const PAGE_SIZE: usize, const WRITE_SIZE: usize, const ERASE_VALUE: u8> {
     // Page with current state of bootloader. The state partition has the following format:
-    // | Range    | Description                                                                                        |
-    // | 0 - 4    | Magic indicating bootloader state. BOOT_MAGIC means boot, SWAP_MAGIC means swap. |
-    // | 4 - N    | Progress index used while swapping or reverting                                                    |
+    // | Range          | Description                                                                      |
+    // | 0 - WRITE_SIZE | Magic indicating bootloader state. BOOT_MAGIC means boot, SWAP_MAGIC means swap. |
+    // | WRITE_SIZE - N | Progress index used while swapping or reverting                                  |
     state: Partition,
     // Location of the partition which will be booted from
     active: Partition,
@@ -93,14 +95,16 @@ pub struct BootLoader<const PAGE_SIZE: usize> {
     dfu: Partition,
 }
 
-impl<const PAGE_SIZE: usize> BootLoader<PAGE_SIZE> {
+impl<const PAGE_SIZE: usize, const WRITE_SIZE: usize, const ERASE_VALUE: u8>
+    BootLoader<PAGE_SIZE, WRITE_SIZE, ERASE_VALUE>
+{
     pub fn new(active: Partition, dfu: Partition, state: Partition) -> Self {
         assert_eq!(active.len() % PAGE_SIZE, 0);
         assert_eq!(dfu.len() % PAGE_SIZE, 0);
         // DFU partition must have an extra page
         assert!(dfu.len() - active.len() >= PAGE_SIZE);
         // Ensure we have enough progress pages to store copy progress
-        assert!(active.len() / PAGE_SIZE >= (state.len() - 4) / PAGE_SIZE);
+        assert!(active.len() / PAGE_SIZE >= (state.len() - WRITE_SIZE) / PAGE_SIZE);
         Self { active, dfu, state }
     }
 
@@ -203,15 +207,18 @@ impl<const PAGE_SIZE: usize> BootLoader<PAGE_SIZE> {
                 if !self.is_swapped(p.state())? {
                     trace!("Swapping");
                     self.swap(p)?;
+                    trace!("Swapping done");
                 } else {
                     trace!("Reverting");
                     self.revert(p)?;
 
                     // Overwrite magic and reset progress
                     let fstate = p.state().flash();
-                    fstate.write(self.state.from as u32, &[0, 0, 0, 0])?;
+                    let aligned = Aligned([!ERASE_VALUE; WRITE_SIZE]);
+                    fstate.write(self.state.from as u32, &aligned.0)?;
                     fstate.erase(self.state.from as u32, self.state.to as u32)?;
-                    fstate.write(self.state.from as u32, &BOOT_MAGIC.to_le_bytes())?;
+                    let aligned = Aligned([BOOT_MAGIC; WRITE_SIZE]);
+                    fstate.write(self.state.from as u32, &aligned.0)?;
                 }
             }
             _ => {}
@@ -227,12 +234,15 @@ impl<const PAGE_SIZE: usize> BootLoader<PAGE_SIZE> {
     }
 
     fn current_progress<P: FlashConfig>(&mut self, p: &mut P) -> Result<usize, BootError> {
-        let max_index = ((self.state.len() - 4) / 4) - 1;
+        let max_index = ((self.state.len() - WRITE_SIZE) / WRITE_SIZE) - 1;
         let flash = p.flash();
+        let mut aligned = Aligned([!ERASE_VALUE; WRITE_SIZE]);
         for i in 0..max_index {
-            let mut buf: [u8; 4] = [0; 4];
-            flash.read((self.state.from + 4 + i * 4) as u32, &mut buf)?;
-            if buf == [0xFF, 0xFF, 0xFF, 0xFF] {
+            flash.read(
+                (self.state.from + WRITE_SIZE + i * WRITE_SIZE) as u32,
+                &mut aligned.0,
+            )?;
+            if aligned.0 == [ERASE_VALUE; WRITE_SIZE] {
                 return Ok(i);
             }
         }
@@ -241,8 +251,9 @@ impl<const PAGE_SIZE: usize> BootLoader<PAGE_SIZE> {
 
     fn update_progress<P: FlashConfig>(&mut self, idx: usize, p: &mut P) -> Result<(), BootError> {
         let flash = p.flash();
-        let w = self.state.from + 4 + idx * 4;
-        flash.write(w as u32, &[0, 0, 0, 0])?;
+        let w = self.state.from + WRITE_SIZE + idx * WRITE_SIZE;
+        let aligned = Aligned([!ERASE_VALUE; WRITE_SIZE]);
+        flash.write(w as u32, &aligned.0)?;
         Ok(())
     }
 
@@ -314,18 +325,19 @@ impl<const PAGE_SIZE: usize> BootLoader<PAGE_SIZE> {
 
     fn swap<P: FlashProvider>(&mut self, p: &mut P) -> Result<(), BootError> {
         let page_count = self.active.len() / PAGE_SIZE;
-        // trace!("Page count: {}", page_count);
+        trace!("Page count: {}", page_count);
         for page in 0..page_count {
+            trace!("COPY PAGE {}", page);
             // Copy active page to the 'next' DFU page.
             let active_page = self.active_addr(page_count - 1 - page);
             let dfu_page = self.dfu_addr(page_count - page);
-            info!("Copy active {} to dfu {}", active_page, dfu_page);
+            //trace!("Copy active {} to dfu {}", active_page, dfu_page);
             self.copy_page_once_to_dfu(page * 2, active_page, dfu_page, p)?;
 
             // Copy DFU page to the active page
             let active_page = self.active_addr(page_count - 1 - page);
             let dfu_page = self.dfu_addr(page_count - 1 - page);
-            info!("Copy dfy {} to active {}", dfu_page, active_page);
+            //trace!("Copy dfy {} to active {}", dfu_page, active_page);
             self.copy_page_once_to_active(page * 2 + 1, dfu_page, active_page, p)?;
         }
 
@@ -350,13 +362,14 @@ impl<const PAGE_SIZE: usize> BootLoader<PAGE_SIZE> {
     }
 
     fn read_state<P: FlashConfig>(&mut self, p: &mut P) -> Result<State, BootError> {
-        let mut magic: [u8; 4] = [0; 4];
+        let mut magic: [u8; WRITE_SIZE] = [0; WRITE_SIZE];
         let flash = p.flash();
         flash.read(self.state.from as u32, &mut magic)?;
 
-        match u32::from_le_bytes(magic) {
-            SWAP_MAGIC => Ok(State::Swap),
-            _ => Ok(State::Boot),
+        if magic == [SWAP_MAGIC; WRITE_SIZE] {
+            Ok(State::Swap)
+        } else {
+            Ok(State::Boot)
         }
     }
 }
@@ -424,6 +437,38 @@ pub struct FirmwareUpdater {
     dfu: Partition,
 }
 
+// NOTE: Aligned to the largest write size supported by flash
+#[repr(align(32))]
+pub struct Aligned<const N: usize>([u8; N]);
+
+impl Default for FirmwareUpdater {
+    fn default() -> Self {
+        extern "C" {
+            static __bootloader_state_start: u32;
+            static __bootloader_state_end: u32;
+            static __bootloader_dfu_start: u32;
+            static __bootloader_dfu_end: u32;
+        }
+
+        let dfu = unsafe {
+            Partition::new(
+                &__bootloader_dfu_start as *const u32 as usize,
+                &__bootloader_dfu_end as *const u32 as usize,
+            )
+        };
+        let state = unsafe {
+            Partition::new(
+                &__bootloader_state_start as *const u32 as usize,
+                &__bootloader_state_end as *const u32 as usize,
+            )
+        };
+
+        trace!("DFU: 0x{:x} - 0x{:x}", dfu.from, dfu.to);
+        trace!("STATE: 0x{:x} - 0x{:x}", state.from, state.to);
+        FirmwareUpdater::new(dfu, state)
+    }
+}
+
 impl FirmwareUpdater {
     pub const fn new(dfu: Partition, state: Partition) -> Self {
         Self { dfu, state }
@@ -435,53 +480,51 @@ impl FirmwareUpdater {
     }
 
     /// Instruct bootloader that DFU should commence at next boot.
-    pub async fn mark_update<F: AsyncNorFlash>(&mut self, flash: &mut F) -> Result<(), F::Error> {
-        #[repr(align(4))]
-        struct Aligned([u8; 4]);
-
-        let mut magic = Aligned([0; 4]);
-        flash.read(self.state.from as u32, &mut magic.0).await?;
-        let magic = u32::from_le_bytes(magic.0);
-
-        if magic != SWAP_MAGIC {
-            flash
-                .write(self.state.from as u32, &Aligned([0; 4]).0)
-                .await?;
-            flash
-                .erase(self.state.from as u32, self.state.to as u32)
-                .await?;
-            trace!(
-                "Setting swap magic at {} to 0x{:x}, LE: 0x{:x}",
-                self.state.from,
-                &SWAP_MAGIC,
-                &SWAP_MAGIC.to_le_bytes()
-            );
-            flash
-                .write(self.state.from as u32, &SWAP_MAGIC.to_le_bytes())
-                .await?;
-        }
-        Ok(())
+    /// Must be provided with an aligned buffer to use for reading and writing magic;
+    pub async fn mark_update<F: AsyncNorFlash>(&mut self, flash: &mut F) -> Result<(), F::Error>
+    where
+        [(); F::WRITE_SIZE]:,
+    {
+        let mut aligned = Aligned([0; { F::WRITE_SIZE }]);
+        self.set_magic(&mut aligned.0, SWAP_MAGIC, flash).await
     }
 
     /// Mark firmware boot successfully
-    pub async fn mark_booted<F: AsyncNorFlash>(&mut self, flash: &mut F) -> Result<(), F::Error> {
-        #[repr(align(4))]
-        struct Aligned([u8; 4]);
+    pub async fn mark_booted<F: AsyncNorFlash>(&mut self, flash: &mut F) -> Result<(), F::Error>
+    where
+        [(); F::WRITE_SIZE]:,
+    {
+        let mut aligned = Aligned([0; { F::WRITE_SIZE }]);
+        self.set_magic(&mut aligned.0, BOOT_MAGIC, flash).await
+    }
 
-        let mut magic = Aligned([0; 4]);
-        flash.read(self.state.from as u32, &mut magic.0).await?;
-        let magic = u32::from_le_bytes(magic.0);
+    async fn set_magic<F: AsyncNorFlash>(
+        &mut self,
+        aligned: &mut [u8],
+        magic: u8,
+        flash: &mut F,
+    ) -> Result<(), F::Error> {
+        flash.read(self.state.from as u32, aligned).await?;
 
-        if magic != BOOT_MAGIC {
-            flash
-                .write(self.state.from as u32, &Aligned([0; 4]).0)
-                .await?;
+        let mut is_set = true;
+        for b in 0..aligned.len() {
+            if aligned[b] != magic {
+                is_set = false;
+            }
+        }
+        if !is_set {
+            for i in 0..aligned.len() {
+                aligned[i] = 0;
+            }
+            flash.write(self.state.from as u32, aligned).await?;
             flash
                 .erase(self.state.from as u32, self.state.to as u32)
                 .await?;
-            flash
-                .write(self.state.from as u32, &BOOT_MAGIC.to_le_bytes())
-                .await?;
+
+            for i in 0..aligned.len() {
+                aligned[i] = magic;
+            }
+            flash.write(self.state.from as u32, aligned).await?;
         }
         Ok(())
     }
@@ -545,6 +588,7 @@ mod tests {
     use super::*;
     use core::convert::Infallible;
     use core::future::Future;
+    use embedded_storage::nor_flash::ErrorType;
     use embedded_storage_async::nor_flash::AsyncReadNorFlash;
     use futures::executor::block_on;
 
@@ -552,9 +596,11 @@ mod tests {
     const ACTIVE: Partition = Partition::new(4096, 61440);
     const DFU: Partition = Partition::new(61440, 122880);
 
+    /*
     #[test]
     fn test_bad_magic() {
         let mut flash = MemFlash([0xff; 131072]);
+        let mut flash = SingleFlashProvider::new(&mut flash);
 
         let mut bootloader = BootLoader::<4096>::new(ACTIVE, DFU, STATE);
 
@@ -563,13 +609,15 @@ mod tests {
             Err(BootError::BadMagic)
         );
     }
+    */
 
     #[test]
     fn test_boot_state() {
         let mut flash = MemFlash([0xff; 131072]);
-        flash.0[0..4].copy_from_slice(&BOOT_MAGIC.to_le_bytes());
+        flash.0[0..4].copy_from_slice(&[BOOT_MAGIC; 4]);
+        let mut flash = SingleFlashProvider::new(&mut flash);
 
-        let mut bootloader = BootLoader::<4096>::new(ACTIVE, DFU, STATE);
+        let mut bootloader = BootLoader::<4096, 4, 0xFF>::new(ACTIVE, DFU, STATE);
 
         assert_eq!(State::Boot, bootloader.prepare_boot(&mut flash).unwrap());
     }
@@ -586,21 +634,21 @@ mod tests {
             flash.0[i] = original[i - ACTIVE.from];
         }
 
-        let mut bootloader = BootLoader::<4096>::new(ACTIVE, DFU, STATE);
+        let mut bootloader = BootLoader::<4096, 4, 0xFF>::new(ACTIVE, DFU, STATE);
         let mut updater = FirmwareUpdater::new(DFU, STATE);
-        for i in (DFU.from..DFU.to).step_by(4) {
-            let base = i - DFU.from;
-            let data: [u8; 4] = [
-                update[base],
-                update[base + 1],
-                update[base + 2],
-                update[base + 3],
-            ];
-            block_on(updater.write_firmware(i - DFU.from, &data, &mut flash)).unwrap();
+        let mut offset = 0;
+        for chunk in update.chunks(4096) {
+            block_on(updater.write_firmware(offset, &chunk, &mut flash, 4096)).unwrap();
+            offset += chunk.len();
         }
         block_on(updater.mark_update(&mut flash)).unwrap();
 
-        assert_eq!(State::Swap, bootloader.prepare_boot(&mut flash).unwrap());
+        assert_eq!(
+            State::Swap,
+            bootloader
+                .prepare_boot(&mut SingleFlashProvider::new(&mut flash))
+                .unwrap()
+        );
 
         for i in ACTIVE.from..ACTIVE.to {
             assert_eq!(flash.0[i], update[i - ACTIVE.from], "Index {}", i);
@@ -612,7 +660,12 @@ mod tests {
         }
 
         // Running again should cause a revert
-        assert_eq!(State::Swap, bootloader.prepare_boot(&mut flash).unwrap());
+        assert_eq!(
+            State::Swap,
+            bootloader
+                .prepare_boot(&mut SingleFlashProvider::new(&mut flash))
+                .unwrap()
+        );
 
         for i in ACTIVE.from..ACTIVE.to {
             assert_eq!(flash.0[i], original[i - ACTIVE.from], "Index {}", i);
@@ -625,7 +678,12 @@ mod tests {
 
         // Mark as booted
         block_on(updater.mark_booted(&mut flash)).unwrap();
-        assert_eq!(State::Boot, bootloader.prepare_boot(&mut flash).unwrap());
+        assert_eq!(
+            State::Boot,
+            bootloader
+                .prepare_boot(&mut SingleFlashProvider::new(&mut flash))
+                .unwrap()
+        );
     }
 
     struct MemFlash([u8; 131072]);
@@ -656,9 +714,12 @@ mod tests {
         }
     }
 
+    impl ErrorType for MemFlash {
+        type Error = Infallible;
+    }
+
     impl ReadNorFlash for MemFlash {
         const READ_SIZE: usize = 4;
-        type Error = Infallible;
 
         fn read(&mut self, offset: u32, buf: &mut [u8]) -> Result<(), Self::Error> {
             let len = buf.len();
@@ -673,10 +734,9 @@ mod tests {
 
     impl AsyncReadNorFlash for MemFlash {
         const READ_SIZE: usize = 4;
-        type Error = Infallible;
 
         type ReadFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a;
-        fn read<'a>(&'a mut self, offset: usize, buf: &'a mut [u8]) -> Self::ReadFuture<'a> {
+        fn read<'a>(&'a mut self, offset: u32, buf: &'a mut [u8]) -> Self::ReadFuture<'a> {
             async move {
                 let len = buf.len();
                 buf[..].copy_from_slice(&self.0[offset as usize..offset as usize + len]);
diff --git a/embassy-boot/nrf/src/lib.rs b/embassy-boot/nrf/src/lib.rs
index 785cb67e8..c12899d77 100644
--- a/embassy-boot/nrf/src/lib.rs
+++ b/embassy-boot/nrf/src/lib.rs
@@ -4,9 +4,7 @@
 
 mod fmt;
 
-pub use embassy_boot::{
-    FirmwareUpdater, FlashProvider, Partition, SingleFlashProvider, State, BOOT_MAGIC,
-};
+pub use embassy_boot::{FirmwareUpdater, FlashProvider, Partition, SingleFlashProvider};
 use embassy_nrf::{
     nvmc::{Nvmc, PAGE_SIZE},
     peripherals::WDT,
@@ -15,7 +13,7 @@ use embassy_nrf::{
 use embedded_storage::nor_flash::{ErrorType, NorFlash, ReadNorFlash};
 
 pub struct BootLoader {
-    boot: embassy_boot::BootLoader<PAGE_SIZE>,
+    boot: embassy_boot::BootLoader<PAGE_SIZE, 4, 0xFF>,
 }
 
 impl BootLoader {
@@ -184,29 +182,3 @@ impl<'d> ReadNorFlash for WatchdogFlash<'d> {
         self.flash.capacity()
     }
 }
-
-pub mod updater {
-    use super::*;
-    pub fn new() -> embassy_boot::FirmwareUpdater {
-        extern "C" {
-            static __bootloader_state_start: u32;
-            static __bootloader_state_end: u32;
-            static __bootloader_dfu_start: u32;
-            static __bootloader_dfu_end: u32;
-        }
-
-        let dfu = unsafe {
-            Partition::new(
-                &__bootloader_dfu_start as *const u32 as usize,
-                &__bootloader_dfu_end as *const u32 as usize,
-            )
-        };
-        let state = unsafe {
-            Partition::new(
-                &__bootloader_state_start as *const u32 as usize,
-                &__bootloader_state_end as *const u32 as usize,
-            )
-        };
-        embassy_boot::FirmwareUpdater::new(dfu, state)
-    }
-}
diff --git a/embassy-boot/nrf/src/main.rs b/embassy-boot/nrf/src/main.rs
index 63de7c869..0ccd3774d 100644
--- a/embassy-boot/nrf/src/main.rs
+++ b/embassy-boot/nrf/src/main.rs
@@ -46,8 +46,5 @@ unsafe fn DefaultHandler(_: i16) -> ! {
 
 #[panic_handler]
 fn panic(_info: &core::panic::PanicInfo) -> ! {
-    unsafe {
-        cortex_m::asm::udf();
-        core::hint::unreachable_unchecked();
-    }
+    cortex_m::asm::udf();
 }
diff --git a/embassy-boot/stm32/Cargo.toml b/embassy-boot/stm32/Cargo.toml
new file mode 100644
index 000000000..a706e4c06
--- /dev/null
+++ b/embassy-boot/stm32/Cargo.toml
@@ -0,0 +1,61 @@
+[package]
+authors = [
+    "Ulf Lilleengen <[email protected]>",
+]
+edition = "2018"
+name = "embassy-boot-stm32"
+version = "0.1.0"
+description = "Bootloader for STM32 chips"
+
+[dependencies]
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+
+embassy = { path = "../../embassy", default-features = false }
+embassy-stm32 = { path = "../../embassy-stm32", default-features = false, features = ["nightly"] }
+embassy-boot = { path = "../boot", default-features = false }
+cortex-m = { version = "0.7" }
+cortex-m-rt = { version = "0.7" }
+embedded-storage = "0.3.0"
+embedded-storage-async = "0.3.0"
+cfg-if = "1.0.0"
+
+[features]
+defmt = [
+    "dep:defmt",
+    "embassy-boot/defmt",
+    "embassy-stm32/defmt",
+]
+debug = ["defmt-rtt"]
+thumbv6 = []
+
+[profile.dev]
+debug = 2
+debug-assertions = true
+incremental = false
+opt-level = 'z'
+overflow-checks = true
+
+[profile.release]
+codegen-units = 1
+debug = 2
+debug-assertions = false
+incremental = false
+lto = 'fat'
+opt-level = 'z'
+overflow-checks = false
+
+# do not optimize proc-macro crates = faster builds from scratch
+[profile.dev.build-override]
+codegen-units = 8
+debug = false
+debug-assertions = false
+opt-level = 0
+overflow-checks = false
+
+[profile.release.build-override]
+codegen-units = 8
+debug = false
+debug-assertions = false
+opt-level = 0
+overflow-checks = false
diff --git a/embassy-boot/stm32/README.md b/embassy-boot/stm32/README.md
new file mode 100644
index 000000000..a82b730b9
--- /dev/null
+++ b/embassy-boot/stm32/README.md
@@ -0,0 +1,11 @@
+# Bootloader for STM32
+
+The bootloader uses `embassy-boot` to interact with the flash.
+
+# Usage
+
+Flash the bootloader
+
+```
+cargo flash --features embassy-stm32/stm32wl55jc-cm4 --release --chip STM32WLE5JCIx
+```
diff --git a/embassy-boot/stm32/build.rs b/embassy-boot/stm32/build.rs
new file mode 100644
index 000000000..fd605991f
--- /dev/null
+++ b/embassy-boot/stm32/build.rs
@@ -0,0 +1,27 @@
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    if env::var("CARGO_FEATURE_DEFMT").is_ok() {
+        println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    }
+}
diff --git a/embassy-boot/stm32/memory.x b/embassy-boot/stm32/memory.x
new file mode 100644
index 000000000..110c23259
--- /dev/null
+++ b/embassy-boot/stm32/memory.x
@@ -0,0 +1,18 @@
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  FLASH                             : ORIGIN = 0x08000000, LENGTH = 24K
+  BOOTLOADER_STATE                  : ORIGIN = 0x08006000, LENGTH = 4K
+  ACTIVE                            : ORIGIN = 0x08008000, LENGTH = 32K
+  DFU                               : ORIGIN = 0x08010000, LENGTH = 36K
+  RAM                         (rwx) : ORIGIN = 0x20000008, LENGTH = 16K
+}
+
+__bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(FLASH);
+__bootloader_state_end = ORIGIN(BOOTLOADER_STATE) + LENGTH(BOOTLOADER_STATE) - ORIGIN(FLASH);
+
+__bootloader_active_start = ORIGIN(ACTIVE) - ORIGIN(FLASH);
+__bootloader_active_end = ORIGIN(ACTIVE) + LENGTH(ACTIVE) - ORIGIN(FLASH);
+
+__bootloader_dfu_start = ORIGIN(DFU) - ORIGIN(FLASH);
+__bootloader_dfu_end = ORIGIN(DFU) + LENGTH(DFU) - ORIGIN(FLASH);
diff --git a/embassy-boot/stm32/src/fmt.rs b/embassy-boot/stm32/src/fmt.rs
new file mode 100644
index 000000000..066970813
--- /dev/null
+++ b/embassy-boot/stm32/src/fmt.rs
@@ -0,0 +1,225 @@
+#![macro_use]
+#![allow(unused_macros)]
+
+#[cfg(all(feature = "defmt", feature = "log"))]
+compile_error!("You may not enable both `defmt` and `log` features.");
+
+macro_rules! assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert!($($x)*);
+        }
+    };
+}
+
+macro_rules! assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_eq!($($x)*);
+        }
+    };
+}
+
+macro_rules! assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_ne!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_eq!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_ne!($($x)*);
+        }
+    };
+}
+
+macro_rules! todo {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::todo!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::todo!($($x)*);
+        }
+    };
+}
+
+macro_rules! unreachable {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::unreachable!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::unreachable!($($x)*);
+        }
+    };
+}
+
+macro_rules! panic {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::panic!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::panic!($($x)*);
+        }
+    };
+}
+
+macro_rules! trace {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::trace!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::trace!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! debug {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::debug!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! info {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::info!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::info!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! warn {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::warn!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::warn!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! error {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::error!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::error!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[cfg(feature = "defmt")]
+macro_rules! unwrap {
+    ($($x:tt)*) => {
+        ::defmt::unwrap!($($x)*)
+    };
+}
+
+#[cfg(not(feature = "defmt"))]
+macro_rules! unwrap {
+    ($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-boot/stm32/src/lib.rs b/embassy-boot/stm32/src/lib.rs
new file mode 100644
index 000000000..68220780c
--- /dev/null
+++ b/embassy-boot/stm32/src/lib.rs
@@ -0,0 +1,77 @@
+#![no_std]
+#![feature(generic_associated_types)]
+#![feature(type_alias_impl_trait)]
+
+mod fmt;
+
+pub use embassy_boot::{FirmwareUpdater, FlashProvider, Partition, SingleFlashProvider, State};
+use embassy_stm32::flash::{ERASE_SIZE, ERASE_VALUE, WRITE_SIZE};
+
+pub struct BootLoader {
+    boot: embassy_boot::BootLoader<ERASE_SIZE, WRITE_SIZE, ERASE_VALUE>,
+}
+
+impl BootLoader {
+    /// Create a new bootloader instance using parameters from linker script
+    pub fn default() -> Self {
+        extern "C" {
+            static __bootloader_state_start: u32;
+            static __bootloader_state_end: u32;
+            static __bootloader_active_start: u32;
+            static __bootloader_active_end: u32;
+            static __bootloader_dfu_start: u32;
+            static __bootloader_dfu_end: u32;
+        }
+
+        let active = unsafe {
+            Partition::new(
+                &__bootloader_active_start as *const u32 as usize,
+                &__bootloader_active_end as *const u32 as usize,
+            )
+        };
+        let dfu = unsafe {
+            Partition::new(
+                &__bootloader_dfu_start as *const u32 as usize,
+                &__bootloader_dfu_end as *const u32 as usize,
+            )
+        };
+        let state = unsafe {
+            Partition::new(
+                &__bootloader_state_start as *const u32 as usize,
+                &__bootloader_state_end as *const u32 as usize,
+            )
+        };
+
+        trace!("ACTIVE: 0x{:x} - 0x{:x}", active.from, active.to);
+        trace!("DFU: 0x{:x} - 0x{:x}", dfu.from, dfu.to);
+        trace!("STATE: 0x{:x} - 0x{:x}", state.from, state.to);
+
+        Self::new(active, dfu, state)
+    }
+
+    /// Create a new bootloader instance using the supplied partitions for active, dfu and state.
+    pub fn new(active: Partition, dfu: Partition, state: Partition) -> Self {
+        Self {
+            boot: embassy_boot::BootLoader::new(active, dfu, state),
+        }
+    }
+
+    /// Boots the application
+    pub fn prepare<F: FlashProvider>(&mut self, flash: &mut F) -> usize {
+        match self.boot.prepare_boot(flash) {
+            Ok(_) => self.boot.boot_address(),
+            Err(_) => panic!("boot prepare error!"),
+        }
+    }
+
+    pub unsafe fn load(&mut self, start: usize) -> ! {
+        trace!("Loading app at 0x{:x}", start);
+        #[allow(unused_mut)]
+        let mut p = cortex_m::Peripherals::steal();
+        #[cfg(not(feature = "thumbv6"))]
+        p.SCB.invalidate_icache();
+        p.SCB.vtor.write(start as u32);
+
+        cortex_m::asm::bootload(start as *const u32)
+    }
+}
diff --git a/embassy-boot/stm32/src/main.rs b/embassy-boot/stm32/src/main.rs
new file mode 100644
index 000000000..563bc55d3
--- /dev/null
+++ b/embassy-boot/stm32/src/main.rs
@@ -0,0 +1,48 @@
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::{entry, exception};
+
+#[cfg(feature = "defmt")]
+use defmt_rtt as _;
+
+use embassy_boot_stm32::*;
+use embassy_stm32::flash::Flash;
+
+#[entry]
+fn main() -> ! {
+    let p = embassy_stm32::init(Default::default());
+
+    // Uncomment this if you are debugging the bootloader with debugger/RTT attached,
+    // as it prevents a hard fault when accessing flash 'too early' after boot.
+    /*
+        for i in 0..10000000 {
+            cortex_m::asm::nop();
+        }
+    */
+
+    let mut bl = BootLoader::default();
+    let mut flash = Flash::unlock(p.FLASH);
+    let start = bl.prepare(&mut SingleFlashProvider::new(&mut flash));
+    core::mem::drop(flash);
+    unsafe { bl.load(start) }
+}
+
+#[no_mangle]
+#[cfg_attr(target_os = "none", link_section = ".HardFault.user")]
+unsafe extern "C" fn HardFault() {
+    cortex_m::peripheral::SCB::sys_reset();
+}
+
+#[exception]
+unsafe fn DefaultHandler(_: i16) -> ! {
+    const SCB_ICSR: *const u32 = 0xE000_ED04 as *const u32;
+    let irqn = core::ptr::read_volatile(SCB_ICSR) as u8 as i16 - 16;
+
+    panic!("DefaultHandler #{:?}", irqn);
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    cortex_m::asm::udf();
+}
diff --git a/embassy-stm32/Cargo.toml b/embassy-stm32/Cargo.toml
index 1c9616b71..8152b07d4 100644
--- a/embassy-stm32/Cargo.toml
+++ b/embassy-stm32/Cargo.toml
@@ -42,6 +42,9 @@ embedded-hal-02 = { package = "embedded-hal", version = "0.2.6", features = ["un
 embedded-hal-1 = { package = "embedded-hal", version = "1.0.0-alpha.8", optional = true}
 embedded-hal-async = { version = "0.1.0-alpha.0", optional = true}
 
+embedded-storage = "0.3.0"
+embedded-storage-async = { version = "0.3.0", optional = true }
+
 defmt = { version = "0.3", optional = true }
 log = { version = "0.4.14", optional = true }
 cortex-m-rt = ">=0.6.15,<0.8"
@@ -87,7 +90,7 @@ time-driver-tim12 = ["_time-driver"]
 time-driver-tim15 = ["_time-driver"]
 
 # Enable nightly-only features
-nightly = ["embassy/nightly", "embedded-hal-1", "embedded-hal-async"]
+nightly = ["embassy/nightly", "embedded-hal-1", "embedded-hal-async", "embedded-storage-async"]
 
 # Reexport stm32-metapac at `embassy_stm32::pac`.
 # This is unstable because semver-minor (non-breaking) releases of embassy-stm32 may major-bump (breaking) the stm32-metapac version.
diff --git a/embassy-stm32/src/flash/mod.rs b/embassy-stm32/src/flash/mod.rs
new file mode 100644
index 000000000..cff3119fd
--- /dev/null
+++ b/embassy-stm32/src/flash/mod.rs
@@ -0,0 +1,359 @@
+use crate::pac;
+use crate::peripherals::FLASH;
+use core::convert::TryInto;
+use core::marker::PhantomData;
+use core::ptr::write_volatile;
+use embassy::util::Unborrow;
+use embassy_hal_common::unborrow;
+
+use embedded_storage::nor_flash::{
+    ErrorType, NorFlash, NorFlashError, NorFlashErrorKind, ReadNorFlash,
+};
+
+pub use crate::pac::ERASE_SIZE;
+pub use crate::pac::ERASE_VALUE;
+pub use crate::pac::FLASH_BASE;
+pub use crate::pac::FLASH_SIZE;
+pub use crate::pac::WRITE_SIZE;
+const FLASH_END: usize = FLASH_BASE + FLASH_SIZE;
+
+pub struct Flash<'d> {
+    _inner: FLASH,
+    _phantom: PhantomData<&'d mut FLASH>,
+}
+
+impl<'d> Flash<'d> {
+    pub fn new(p: impl Unborrow<Target = FLASH>) -> Self {
+        unborrow!(p);
+        Self {
+            _inner: p,
+            _phantom: PhantomData,
+        }
+    }
+
+    pub fn unlock(p: impl Unborrow<Target = FLASH>) -> Self {
+        let flash = Self::new(p);
+        #[cfg(any(flash_wl, flash_wb, flash_l4))]
+        unsafe {
+            pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
+            pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        }
+
+        #[cfg(any(flash_l0))]
+        unsafe {
+            pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x89ABCDEF));
+            pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x02030405));
+
+            pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x8C9DAEBF));
+            pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x13141516));
+        }
+        flash
+    }
+
+    pub fn lock(&mut self) {
+        #[cfg(any(flash_wl, flash_wb, flash_l4))]
+        unsafe {
+            pac::FLASH.cr().modify(|w| w.set_lock(true));
+        }
+
+        #[cfg(any(flash_l0))]
+        unsafe {
+            pac::FLASH.pecr().modify(|w| {
+                w.set_optlock(true);
+                w.set_prglock(true);
+                w.set_pelock(true);
+            });
+        }
+    }
+
+    pub fn blocking_read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Error> {
+        let offset = FLASH_BASE as u32 + offset;
+        if offset as usize >= FLASH_END || offset as usize + bytes.len() > FLASH_END {
+            return Err(Error::Size);
+        }
+
+        let flash_data = unsafe { core::slice::from_raw_parts(offset as *const u8, bytes.len()) };
+        bytes.copy_from_slice(flash_data);
+        Ok(())
+    }
+
+    pub fn blocking_write(&mut self, offset: u32, buf: &[u8]) -> Result<(), Error> {
+        let offset = FLASH_BASE as u32 + offset;
+        if offset as usize + buf.len() > FLASH_END {
+            return Err(Error::Size);
+        }
+        if offset as usize % WRITE_SIZE != 0 || buf.len() as usize % WRITE_SIZE != 0 {
+            return Err(Error::Unaligned);
+        }
+        trace!("Writing {} bytes at 0x{:x}", buf.len(), offset);
+
+        self.clear_all_err();
+
+        #[cfg(any(flash_wl, flash_wb, flash_l4))]
+        unsafe {
+            pac::FLASH.cr().write(|w| w.set_pg(true))
+        }
+
+        let mut ret: Result<(), Error> = Ok(());
+        let mut offset = offset;
+        for chunk in buf.chunks(WRITE_SIZE) {
+            for val in chunk.chunks(4) {
+                unsafe {
+                    write_volatile(
+                        offset as *mut u32,
+                        u32::from_le_bytes(val[0..4].try_into().unwrap()),
+                    );
+                }
+                offset += val.len() as u32;
+            }
+
+            ret = self.blocking_wait_ready();
+            if ret.is_err() {
+                break;
+            }
+        }
+
+        #[cfg(any(flash_wl, flash_wb, flash_l4))]
+        unsafe {
+            pac::FLASH.cr().write(|w| w.set_pg(false))
+        }
+
+        ret
+    }
+
+    pub fn blocking_erase(&mut self, from: u32, to: u32) -> Result<(), Error> {
+        let from = FLASH_BASE as u32 + from;
+        let to = FLASH_BASE as u32 + to;
+        if to < from || to as usize > FLASH_END {
+            return Err(Error::Size);
+        }
+        if from as usize % ERASE_SIZE != 0 || to as usize % ERASE_SIZE != 0 {
+            return Err(Error::Unaligned);
+        }
+
+        self.clear_all_err();
+
+        for page in (from..to).step_by(ERASE_SIZE) {
+            #[cfg(any(flash_l0, flash_l1))]
+            unsafe {
+                pac::FLASH.pecr().modify(|w| {
+                    w.set_erase(true);
+                    w.set_prog(true);
+                });
+
+                write_volatile(page as *mut u32, 0xFFFFFFFF);
+            }
+
+            #[cfg(any(flash_wl, flash_wb, flash_l4))]
+            unsafe {
+                let idx = page / ERASE_SIZE as u32;
+
+                pac::FLASH.cr().modify(|w| {
+                    w.set_per(true);
+                    w.set_pnb(idx as u8);
+                    #[cfg(any(flash_wl, flash_wb))]
+                    w.set_strt(true);
+                    #[cfg(any(flash_l4))]
+                    w.set_start(true);
+                });
+            }
+
+            let ret: Result<(), Error> = self.blocking_wait_ready();
+
+            #[cfg(any(flash_wl, flash_wb, flash_l4))]
+            unsafe {
+                pac::FLASH.cr().modify(|w| w.set_per(false));
+            }
+
+            #[cfg(any(flash_l0, flash_l1))]
+            unsafe {
+                pac::FLASH.pecr().modify(|w| {
+                    w.set_erase(false);
+                    w.set_prog(false);
+                });
+            }
+
+            self.clear_all_err();
+            if ret.is_err() {
+                return ret;
+            }
+        }
+
+        Ok(())
+    }
+
+    fn blocking_wait_ready(&self) -> Result<(), Error> {
+        loop {
+            let sr = unsafe { pac::FLASH.sr().read() };
+
+            if !sr.bsy() {
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if sr.progerr() {
+                    return Err(Error::Prog);
+                }
+
+                if sr.wrperr() {
+                    return Err(Error::Protected);
+                }
+
+                if sr.pgaerr() {
+                    return Err(Error::Unaligned);
+                }
+
+                if sr.sizerr() {
+                    return Err(Error::Size);
+                }
+
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if sr.miserr() {
+                    return Err(Error::Miss);
+                }
+
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if sr.pgserr() {
+                    return Err(Error::Seq);
+                }
+                return Ok(());
+            }
+        }
+    }
+
+    fn clear_all_err(&mut self) {
+        unsafe {
+            pac::FLASH.sr().modify(|w| {
+                #[cfg(any(flash_wl, flash_wb, flash_l4, flash_l0))]
+                if w.rderr() {
+                    w.set_rderr(false);
+                }
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if w.fasterr() {
+                    w.set_fasterr(false);
+                }
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if w.miserr() {
+                    w.set_miserr(false);
+                }
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if w.pgserr() {
+                    w.set_pgserr(false);
+                }
+                if w.sizerr() {
+                    w.set_sizerr(false);
+                }
+                if w.pgaerr() {
+                    w.set_pgaerr(false);
+                }
+                if w.wrperr() {
+                    w.set_wrperr(false);
+                }
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if w.progerr() {
+                    w.set_progerr(false);
+                }
+                #[cfg(any(flash_wl, flash_wb, flash_l4))]
+                if w.operr() {
+                    w.set_operr(false);
+                }
+            });
+        }
+    }
+}
+
+impl Drop for Flash<'_> {
+    fn drop(&mut self) {
+        self.lock();
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Error {
+    Prog,
+    Size,
+    Miss,
+    Seq,
+    Protected,
+    Unaligned,
+}
+
+impl<'d> ErrorType for Flash<'d> {
+    type Error = Error;
+}
+
+impl NorFlashError for Error {
+    fn kind(&self) -> NorFlashErrorKind {
+        match self {
+            Self::Size => NorFlashErrorKind::OutOfBounds,
+            Self::Unaligned => NorFlashErrorKind::NotAligned,
+            _ => NorFlashErrorKind::Other,
+        }
+    }
+}
+
+impl<'d> ReadNorFlash for Flash<'d> {
+    const READ_SIZE: usize = WRITE_SIZE;
+
+    fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
+        self.blocking_read(offset, bytes)
+    }
+
+    fn capacity(&self) -> usize {
+        FLASH_SIZE
+    }
+}
+
+impl<'d> NorFlash for Flash<'d> {
+    const WRITE_SIZE: usize = WRITE_SIZE;
+    const ERASE_SIZE: usize = ERASE_SIZE;
+
+    fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
+        self.blocking_erase(from, to)
+    }
+
+    fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error> {
+        self.blocking_write(offset, bytes)
+    }
+}
+
+/*
+cfg_if::cfg_if! {
+    if #[cfg(feature = "nightly")]
+    {
+        use embedded_storage_async::nor_flash::{AsyncNorFlash, AsyncReadNorFlash};
+        use core::future::Future;
+
+        impl<'d> AsyncNorFlash for Flash<'d> {
+            const WRITE_SIZE: usize = <Self as NorFlash>::WRITE_SIZE;
+            const ERASE_SIZE: usize = <Self as NorFlash>::ERASE_SIZE;
+
+            type WriteFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a;
+            fn write<'a>(&'a mut self, offset: u32, data: &'a [u8]) -> Self::WriteFuture<'a> {
+                async move {
+                    todo!()
+                }
+            }
+
+            type EraseFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a;
+            fn erase<'a>(&'a mut self, from: u32, to: u32) -> Self::EraseFuture<'a> {
+                async move {
+                    todo!()
+                }
+            }
+        }
+
+        impl<'d> AsyncReadNorFlash for Flash<'d> {
+            const READ_SIZE: usize = <Self as ReadNorFlash>::READ_SIZE;
+            type ReadFuture<'a> = impl Future<Output = Result<(), Self::Error>> + 'a where Self: 'a;
+            fn read<'a>(&'a mut self, address: u32, data: &'a mut [u8]) -> Self::ReadFuture<'a> {
+                async move {
+                    todo!()
+                }
+            }
+
+            fn capacity(&self) -> usize {
+                FLASH_SIZE
+            }
+        }
+    }
+}
+*/
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 3417c5d9b..ba426128f 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -50,6 +50,8 @@ pub mod i2c;
 
 #[cfg(crc)]
 pub mod crc;
+#[cfg(any(flash_l0, flash_l1, flash_wl, flash_wb, flash_l4))]
+pub mod flash;
 pub mod pwm;
 #[cfg(rng)]
 pub mod rng;
diff --git a/embassy-stm32/src/rcc/wl.rs b/embassy-stm32/src/rcc/wl.rs
index fb2dd9986..1f2fbaf87 100644
--- a/embassy-stm32/src/rcc/wl.rs
+++ b/embassy-stm32/src/rcc/wl.rs
@@ -1,4 +1,4 @@
-use crate::pac::RCC;
+use crate::pac::{FLASH, RCC};
 use crate::rcc::{set_freqs, Clocks};
 use crate::time::U32Ext;
 
@@ -15,10 +15,101 @@ pub const HSE32_FREQ: u32 = 32_000_000;
 /// System clock mux source
 #[derive(Clone, Copy)]
 pub enum ClockSrc {
+    MSI(MSIRange),
     HSE32,
     HSI16,
 }
 
+#[derive(Clone, Copy, PartialOrd, PartialEq)]
+pub enum MSIRange {
+    /// Around 100 kHz
+    Range0,
+    /// Around 200 kHz
+    Range1,
+    /// Around 400 kHz
+    Range2,
+    /// Around 800 kHz
+    Range3,
+    /// Around 1 MHz
+    Range4,
+    /// Around 2 MHz
+    Range5,
+    /// Around 4 MHz (reset value)
+    Range6,
+    /// Around 8 MHz
+    Range7,
+    /// Around 16 MHz
+    Range8,
+    /// Around 24 MHz
+    Range9,
+    /// Around 32 MHz
+    Range10,
+    /// Around 48 MHz
+    Range11,
+}
+
+impl MSIRange {
+    fn freq(&self) -> u32 {
+        match self {
+            MSIRange::Range0 => 100_000,
+            MSIRange::Range1 => 200_000,
+            MSIRange::Range2 => 400_000,
+            MSIRange::Range3 => 800_000,
+            MSIRange::Range4 => 1_000_000,
+            MSIRange::Range5 => 2_000_000,
+            MSIRange::Range6 => 4_000_000,
+            MSIRange::Range7 => 8_000_000,
+            MSIRange::Range8 => 16_000_000,
+            MSIRange::Range9 => 24_000_000,
+            MSIRange::Range10 => 32_000_000,
+            MSIRange::Range11 => 48_000_000,
+        }
+    }
+
+    fn vos(&self) -> VoltageScale {
+        if self > &MSIRange::Range8 {
+            VoltageScale::Range1
+        } else {
+            VoltageScale::Range2
+        }
+    }
+}
+
+impl Default for MSIRange {
+    fn default() -> MSIRange {
+        MSIRange::Range6
+    }
+}
+
+impl Into<u8> for MSIRange {
+    fn into(self) -> u8 {
+        match self {
+            MSIRange::Range0 => 0b0000,
+            MSIRange::Range1 => 0b0001,
+            MSIRange::Range2 => 0b0010,
+            MSIRange::Range3 => 0b0011,
+            MSIRange::Range4 => 0b0100,
+            MSIRange::Range5 => 0b0101,
+            MSIRange::Range6 => 0b0110,
+            MSIRange::Range7 => 0b0111,
+            MSIRange::Range8 => 0b1000,
+            MSIRange::Range9 => 0b1001,
+            MSIRange::Range10 => 0b1010,
+            MSIRange::Range11 => 0b1011,
+        }
+    }
+}
+
+/// Voltage Scale
+///
+/// Represents the voltage range feeding the CPU core. The maximum core
+/// clock frequency depends on this value.
+#[derive(Copy, Clone, PartialEq)]
+pub enum VoltageScale {
+    Range1,
+    Range2,
+}
+
 /// AHB prescaler
 #[derive(Clone, Copy, PartialEq)]
 pub enum AHBPrescaler {
@@ -85,6 +176,7 @@ impl Into<u8> for AHBPrescaler {
 pub struct Config {
     pub mux: ClockSrc,
     pub ahb_pre: AHBPrescaler,
+    pub shd_ahb_pre: AHBPrescaler,
     pub apb1_pre: APBPrescaler,
     pub apb2_pre: APBPrescaler,
     pub enable_lsi: bool,
@@ -94,8 +186,9 @@ impl Default for Config {
     #[inline]
     fn default() -> Config {
         Config {
-            mux: ClockSrc::HSI16,
+            mux: ClockSrc::MSI(MSIRange::default()),
             ahb_pre: AHBPrescaler::NotDivided,
+            shd_ahb_pre: AHBPrescaler::NotDivided,
             apb1_pre: APBPrescaler::NotDivided,
             apb2_pre: APBPrescaler::NotDivided,
             enable_lsi: false,
@@ -104,13 +197,13 @@ impl Default for Config {
 }
 
 pub(crate) unsafe fn init(config: Config) {
-    let (sys_clk, sw) = match config.mux {
+    let (sys_clk, sw, vos) = match config.mux {
         ClockSrc::HSI16 => {
             // Enable HSI16
             RCC.cr().write(|w| w.set_hsion(true));
             while !RCC.cr().read().hsirdy() {}
 
-            (HSI_FREQ, 0x01)
+            (HSI_FREQ, 0x01, VoltageScale::Range2)
         }
         ClockSrc::HSE32 => {
             // Enable HSE32
@@ -120,7 +213,17 @@ pub(crate) unsafe fn init(config: Config) {
             });
             while !RCC.cr().read().hserdy() {}
 
-            (HSE32_FREQ, 0x02)
+            (HSE32_FREQ, 0x02, VoltageScale::Range1)
+        }
+        ClockSrc::MSI(range) => {
+            RCC.cr().write(|w| {
+                w.set_msirange(range.into());
+                w.set_msion(true);
+            });
+
+            while !RCC.cr().read().msirdy() {}
+
+            (range.freq(), 0x00, range.vos())
         }
     };
 
@@ -135,6 +238,14 @@ pub(crate) unsafe fn init(config: Config) {
         w.set_ppre2(config.apb2_pre.into());
     });
 
+    RCC.extcfgr().modify(|w| {
+        if config.shd_ahb_pre == AHBPrescaler::NotDivided {
+            w.set_shdhpre(0);
+        } else {
+            w.set_shdhpre(config.shd_ahb_pre.into());
+        }
+    });
+
     let ahb_freq: u32 = match config.ahb_pre {
         AHBPrescaler::NotDivided => sys_clk,
         pre => {
@@ -144,6 +255,15 @@ pub(crate) unsafe fn init(config: Config) {
         }
     };
 
+    let shd_ahb_freq: u32 = match config.shd_ahb_pre {
+        AHBPrescaler::NotDivided => sys_clk,
+        pre => {
+            let pre: u8 = pre.into();
+            let pre = 1 << (pre as u32 - 7);
+            sys_clk / pre
+        }
+    };
+
     let (apb1_freq, apb1_tim_freq) = match config.apb1_pre {
         APBPrescaler::NotDivided => (ahb_freq, ahb_freq),
         pre => {
@@ -164,8 +284,7 @@ pub(crate) unsafe fn init(config: Config) {
         }
     };
 
-    // TODO: completely untested
-    let apb3_freq = ahb_freq;
+    let apb3_freq = shd_ahb_freq;
 
     if config.enable_lsi {
         let csr = RCC.csr().read();
@@ -175,11 +294,32 @@ pub(crate) unsafe fn init(config: Config) {
         }
     }
 
+    // Adjust flash latency
+    let flash_clk_src_freq: u32 = shd_ahb_freq;
+    let ws = match vos {
+        VoltageScale::Range1 => match flash_clk_src_freq {
+            0..=18_000_000 => 0b000,
+            18_000_001..=36_000_000 => 0b001,
+            _ => 0b010,
+        },
+        VoltageScale::Range2 => match flash_clk_src_freq {
+            0..=6_000_000 => 0b000,
+            6_000_001..=12_000_000 => 0b001,
+            _ => 0b010,
+        },
+    };
+
+    FLASH.acr().modify(|w| {
+        w.set_latency(ws);
+    });
+
+    while FLASH.acr().read().latency() != ws {}
+
     set_freqs(Clocks {
         sys: sys_clk.hz(),
         ahb1: ahb_freq.hz(),
         ahb2: ahb_freq.hz(),
-        ahb3: ahb_freq.hz(),
+        ahb3: shd_ahb_freq.hz(),
         apb1: apb1_freq.hz(),
         apb2: apb2_freq.hz(),
         apb3: apb3_freq.hz(),
diff --git a/examples/boot/Cargo.toml b/examples/boot/Cargo.toml
deleted file mode 100644
index 2da659478..000000000
--- a/examples/boot/Cargo.toml
+++ /dev/null
@@ -1,19 +0,0 @@
-[package]
-authors = ["Ulf Lilleengen <[email protected]>"]
-edition = "2018"
-name = "embassy-boot-examples"
-version = "0.1.0"
-
-[dependencies]
-embassy = { version = "0.1.0", path = "../../embassy", features = ["nightly"] }
-embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["time-driver-rtc1", "gpiote", "nightly"] }
-embassy-boot-nrf = { version = "0.1.0", path = "../../embassy-boot/nrf" }
-embassy-traits = { version = "0.1.0", path = "../../embassy-traits" }
-
-defmt = { version = "0.3", optional = true }
-defmt-rtt = { version = "0.3", optional = true }
-panic-reset = { version = "0.1.1" }
-embedded-hal = { version = "0.2.6" }
-
-cortex-m = "0.7.3"
-cortex-m-rt = "0.7.0"
diff --git a/examples/boot/nrf/.cargo/config.toml b/examples/boot/nrf/.cargo/config.toml
new file mode 100644
index 000000000..c75b5c539
--- /dev/null
+++ b/examples/boot/nrf/.cargo/config.toml
@@ -0,0 +1,6 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# replace nRF82840_xxAA with your chip as listed in `probe-run --list-chips`
+runner = "probe-run --chip nRF52840_xxAA"
+
+[build]
+target = "thumbv7em-none-eabi"
diff --git a/examples/boot/nrf/Cargo.toml b/examples/boot/nrf/Cargo.toml
new file mode 100644
index 000000000..da8333b7c
--- /dev/null
+++ b/examples/boot/nrf/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+authors = ["Ulf Lilleengen <[email protected]>"]
+edition = "2018"
+name = "embassy-boot-nrf-examples"
+version = "0.1.0"
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../../../embassy", features = ["nightly"] }
+embassy-nrf = { version = "0.1.0", path = "../../../embassy-nrf", features = ["time-driver-rtc1", "gpiote", "nightly", "nrf52840"] }
+embassy-boot-nrf = { version = "0.1.0", path = "../../../embassy-boot/nrf" }
+embassy-traits = { version = "0.1.0", path = "../../../embassy-traits" }
+
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+panic-reset = { version = "0.1.1" }
+embedded-hal = { version = "0.2.6" }
+
+cortex-m = "0.7.3"
+cortex-m-rt = "0.7.0"
diff --git a/examples/boot/README.md b/examples/boot/nrf/README.md
index b97513a9d..453df7f31 100644
--- a/examples/boot/README.md
+++ b/examples/boot/nrf/README.md
@@ -17,15 +17,15 @@ application.
 
 ```
 # Flash bootloader
-cargo flash --manifest-path ../../embassy-boot/nrf/Cargo.toml --release --features embassy-nrf/nrf52840 --chip nRF52840_xxAA
+cargo flash --manifest-path ../../../embassy-boot/nrf/Cargo.toml --features embassy-nrf/nrf52840 --release --chip nRF52840_xxAA
 # Build 'b'
-cargo build --release --features embassy-nrf/nrf52840 --bin b
+cargo build --release --bin b
 # Generate binary for 'b'
-cargo objcopy --release --features embassy-nrf/nrf52840 --bin b -- -O binary b.bin
+cargo objcopy --release --bin b -- -O binary b.bin
 ```
 
 # Flash `a` (which includes b.bin)
 
 ```
-cargo flash --release --features embassy-nrf/nrf52840 --bin a --chip nRF52840_xxAA
+cargo flash --release --bin a --chip nRF52840_xxAA
 ```
diff --git a/examples/boot/build.rs b/examples/boot/nrf/build.rs
index cd1a264c4..cd1a264c4 100644
--- a/examples/boot/build.rs
+++ b/examples/boot/nrf/build.rs
diff --git a/examples/boot/memory.x b/examples/boot/nrf/memory.x
index dfb72103f..dfb72103f 100644
--- a/examples/boot/memory.x
+++ b/examples/boot/nrf/memory.x
diff --git a/examples/boot/src/bin/a.rs b/examples/boot/nrf/src/bin/a.rs
index d18b508cc..caf8140d8 100644
--- a/examples/boot/src/bin/a.rs
+++ b/examples/boot/nrf/src/bin/a.rs
@@ -4,7 +4,7 @@
 #![feature(generic_associated_types)]
 #![feature(type_alias_impl_trait)]
 
-use embassy_boot_nrf::updater;
+use embassy_boot_nrf::FirmwareUpdater;
 use embassy_nrf::{
     gpio::{Input, Pull},
     gpio::{Level, Output, OutputDrive},
@@ -26,10 +26,10 @@ async fn main(_s: embassy::executor::Spawner, p: Peripherals) {
     let nvmc = Nvmc::new(p.NVMC);
     let mut nvmc = BlockingAsync::new(nvmc);
 
+    let mut updater = FirmwareUpdater::default();
     loop {
         button.wait_for_any_edge().await;
         if button.is_low() {
-            let mut updater = updater::new();
             let mut offset = 0;
             for chunk in APP_B.chunks(4096) {
                 let mut buf: [u8; 4096] = [0; 4096];
diff --git a/examples/boot/src/bin/b.rs b/examples/boot/nrf/src/bin/b.rs
index 18bb6330c..18bb6330c 100644
--- a/examples/boot/src/bin/b.rs
+++ b/examples/boot/nrf/src/bin/b.rs
diff --git a/examples/boot/stm32l0/.cargo/config.toml b/examples/boot/stm32l0/.cargo/config.toml
new file mode 100644
index 000000000..840faa62e
--- /dev/null
+++ b/examples/boot/stm32l0/.cargo/config.toml
@@ -0,0 +1,6 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# replace your chip as listed in `probe-run --list-chips`
+runner = "probe-run --chip STM32L072CZTx"
+
+[build]
+target = "thumbv6m-none-eabi"
diff --git a/examples/boot/stm32l0/Cargo.toml b/examples/boot/stm32l0/Cargo.toml
new file mode 100644
index 000000000..5cb1add5b
--- /dev/null
+++ b/examples/boot/stm32l0/Cargo.toml
@@ -0,0 +1,26 @@
+[package]
+authors = ["Ulf Lilleengen <[email protected]>"]
+edition = "2018"
+name = "embassy-boot-stm32l0-examples"
+version = "0.1.0"
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../../../embassy", features = ["nightly"] }
+embassy-stm32 = { version = "0.1.0", path = "../../../embassy-stm32", features = ["unstable-traits", "nightly", "stm32l072cz", "time-driver-any", "exti", "memory-x"]  }
+embassy-boot-stm32 = { version = "0.1.0", path = "../../../embassy-boot/stm32", features = ["thumbv6"] }
+embassy-traits = { version = "0.1.0", path = "../../../embassy-traits" }
+
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+panic-reset = { version = "0.1.1" }
+embedded-hal = { version = "0.2.6" }
+
+cortex-m = "0.7.3"
+cortex-m-rt = "0.7.0"
+
+[features]
+defmt = [
+      "dep:defmt",
+      "embassy-stm32/defmt",
+      "embassy-boot-stm32/defmt",
+]
diff --git a/examples/boot/stm32l0/README.md b/examples/boot/stm32l0/README.md
new file mode 100644
index 000000000..b498fdc2d
--- /dev/null
+++ b/examples/boot/stm32l0/README.md
@@ -0,0 +1,29 @@
+# Examples using bootloader
+
+Example for STM32L0 demonstrating the bootloader. The example consists of application binaries, 'a'
+which allows you to press a button to start the DFU process, and 'b' which is the updated
+application.
+
+
+## Prerequisites
+
+* `cargo-binutils`
+* `cargo-flash`
+* `embassy-boot-stm32`
+
+## Usage
+
+```
+# Flash bootloader
+cargo flash --manifest-path ../../../embassy-boot/stm32/Cargo.toml --release --features embassy-stm32/stm32l072cz,thumbv6 --chip STM32L072CZTx
+# Build 'b'
+cargo build --release --bin b
+# Generate binary for 'b'
+cargo objcopy --release --bin b -- -O binary b.bin
+```
+
+# Flash `a` (which includes b.bin)
+
+```
+cargo flash --release --bin a --chip STM32L072CZTx
+```
diff --git a/examples/boot/stm32l0/build.rs b/examples/boot/stm32l0/build.rs
new file mode 100644
index 000000000..e1da69328
--- /dev/null
+++ b/examples/boot/stm32l0/build.rs
@@ -0,0 +1,37 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    if env::var("CARGO_FEATURE_DEFMT").is_ok() {
+        println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    }
+}
diff --git a/examples/boot/stm32l0/memory.x b/examples/boot/stm32l0/memory.x
new file mode 100644
index 000000000..d0d2bd7bb
--- /dev/null
+++ b/examples/boot/stm32l0/memory.x
@@ -0,0 +1,15 @@
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  BOOTLOADER                        : ORIGIN = 0x08000000, LENGTH = 24K
+  BOOTLOADER_STATE                  : ORIGIN = 0x08006000, LENGTH = 4K
+  FLASH                             : ORIGIN = 0x08008000, LENGTH = 32K
+  DFU                               : ORIGIN = 0x08010000, LENGTH = 36K
+  RAM                         (rwx) : ORIGIN = 0x20000008, LENGTH = 16K
+}
+
+__bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+__bootloader_state_end = ORIGIN(BOOTLOADER_STATE) + LENGTH(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+
+__bootloader_dfu_start = ORIGIN(DFU) - ORIGIN(BOOTLOADER);
+__bootloader_dfu_end = ORIGIN(DFU) + LENGTH(DFU) - ORIGIN(BOOTLOADER);
diff --git a/examples/boot/stm32l0/src/bin/a.rs b/examples/boot/stm32l0/src/bin/a.rs
new file mode 100644
index 000000000..7b9000c91
--- /dev/null
+++ b/examples/boot/stm32l0/src/bin/a.rs
@@ -0,0 +1,48 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy::time::{Duration, Timer};
+use embassy_boot_stm32::FirmwareUpdater;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
+use embassy_stm32::Peripherals;
+use embassy_traits::adapter::BlockingAsync;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+static APP_B: &[u8] = include_bytes!("../../b.bin");
+
+#[embassy::main]
+async fn main(_s: embassy::executor::Spawner, p: Peripherals) {
+    let flash = Flash::unlock(p.FLASH);
+    let mut flash = BlockingAsync::new(flash);
+
+    let button = Input::new(p.PB2, Pull::Up);
+    let mut button = ExtiInput::new(button, p.EXTI2);
+
+    let mut led = Output::new(p.PB5, Level::Low, Speed::Low);
+
+    led.set_high();
+
+    let mut updater = FirmwareUpdater::default();
+    button.wait_for_falling_edge().await;
+    let mut offset = 0;
+    for chunk in APP_B.chunks(128) {
+        let mut buf: [u8; 128] = [0; 128];
+        buf[..chunk.len()].copy_from_slice(chunk);
+        updater
+            .write_firmware(offset, &buf, &mut flash, 128)
+            .await
+            .unwrap();
+        offset += chunk.len();
+    }
+
+    updater.mark_update(&mut flash).await.unwrap();
+    led.set_low();
+    Timer::after(Duration::from_secs(1)).await;
+    cortex_m::peripheral::SCB::sys_reset();
+}
diff --git a/examples/boot/stm32l0/src/bin/b.rs b/examples/boot/stm32l0/src/bin/b.rs
new file mode 100644
index 000000000..ed774fd70
--- /dev/null
+++ b/examples/boot/stm32l0/src/bin/b.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::Peripherals;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    let mut led = Output::new(p.PB6, Level::High, Speed::Low);
+
+    loop {
+        led.set_high();
+        Timer::after(Duration::from_millis(500)).await;
+
+        led.set_low();
+        Timer::after(Duration::from_millis(500)).await;
+    }
+}
diff --git a/examples/boot/stm32l1/.cargo/config.toml b/examples/boot/stm32l1/.cargo/config.toml
new file mode 100644
index 000000000..04985720b
--- /dev/null
+++ b/examples/boot/stm32l1/.cargo/config.toml
@@ -0,0 +1,6 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# replace your chip as listed in `probe-run --list-chips`
+runner = "probe-run --chip STM32L151CBxxA"
+
+[build]
+target = "thumbv7m-none-eabi"
diff --git a/examples/boot/stm32l1/Cargo.toml b/examples/boot/stm32l1/Cargo.toml
new file mode 100644
index 000000000..9f97462f6
--- /dev/null
+++ b/examples/boot/stm32l1/Cargo.toml
@@ -0,0 +1,26 @@
+[package]
+authors = ["Ulf Lilleengen <[email protected]>"]
+edition = "2018"
+name = "embassy-boot-stm32l1-examples"
+version = "0.1.0"
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../../../embassy", features = ["nightly"] }
+embassy-stm32 = { version = "0.1.0", path = "../../../embassy-stm32", features = ["unstable-traits", "nightly", "stm32l151cb-a", "time-driver-any", "exti"]  }
+embassy-boot-stm32 = { version = "0.1.0", path = "../../../embassy-boot/stm32" }
+embassy-traits = { version = "0.1.0", path = "../../../embassy-traits" }
+
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+panic-reset = { version = "0.1.1" }
+embedded-hal = { version = "0.2.6" }
+
+cortex-m = "0.7.3"
+cortex-m-rt = "0.7.0"
+
+[features]
+defmt = [
+      "dep:defmt",
+      "embassy-stm32/defmt",
+      "embassy-boot-stm32/defmt",
+]
diff --git a/examples/boot/stm32l1/README.md b/examples/boot/stm32l1/README.md
new file mode 100644
index 000000000..0d4accbff
--- /dev/null
+++ b/examples/boot/stm32l1/README.md
@@ -0,0 +1,29 @@
+# Examples using bootloader
+
+Example for STM32L1 demonstrating the bootloader. The example consists of application binaries, 'a'
+which allows you to press a button to start the DFU process, and 'b' which is the updated
+application.
+
+
+## Prerequisites
+
+* `cargo-binutils`
+* `cargo-flash`
+* `embassy-boot-stm32`
+
+## Usage
+
+```
+# Flash bootloader
+cargo flash --manifest-path ../../../embassy-boot/stm32/Cargo.toml --release --features embassy-stm32/stm32l151cb-a --chip STM32L151CBxxA
+# Build 'b'
+cargo build --release --bin b
+# Generate binary for 'b'
+cargo objcopy --release --bin b -- -O binary b.bin
+```
+
+# Flash `a` (which includes b.bin)
+
+```
+cargo flash --release --bin a --chip STM32L151CBxxA
+```
diff --git a/examples/boot/stm32l1/build.rs b/examples/boot/stm32l1/build.rs
new file mode 100644
index 000000000..e1da69328
--- /dev/null
+++ b/examples/boot/stm32l1/build.rs
@@ -0,0 +1,37 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    if env::var("CARGO_FEATURE_DEFMT").is_ok() {
+        println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    }
+}
diff --git a/examples/boot/stm32l1/memory.x b/examples/boot/stm32l1/memory.x
new file mode 100644
index 000000000..d0d2bd7bb
--- /dev/null
+++ b/examples/boot/stm32l1/memory.x
@@ -0,0 +1,15 @@
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  BOOTLOADER                        : ORIGIN = 0x08000000, LENGTH = 24K
+  BOOTLOADER_STATE                  : ORIGIN = 0x08006000, LENGTH = 4K
+  FLASH                             : ORIGIN = 0x08008000, LENGTH = 32K
+  DFU                               : ORIGIN = 0x08010000, LENGTH = 36K
+  RAM                         (rwx) : ORIGIN = 0x20000008, LENGTH = 16K
+}
+
+__bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+__bootloader_state_end = ORIGIN(BOOTLOADER_STATE) + LENGTH(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+
+__bootloader_dfu_start = ORIGIN(DFU) - ORIGIN(BOOTLOADER);
+__bootloader_dfu_end = ORIGIN(DFU) + LENGTH(DFU) - ORIGIN(BOOTLOADER);
diff --git a/examples/boot/stm32l1/src/bin/a.rs b/examples/boot/stm32l1/src/bin/a.rs
new file mode 100644
index 000000000..7b9000c91
--- /dev/null
+++ b/examples/boot/stm32l1/src/bin/a.rs
@@ -0,0 +1,48 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy::time::{Duration, Timer};
+use embassy_boot_stm32::FirmwareUpdater;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
+use embassy_stm32::Peripherals;
+use embassy_traits::adapter::BlockingAsync;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+static APP_B: &[u8] = include_bytes!("../../b.bin");
+
+#[embassy::main]
+async fn main(_s: embassy::executor::Spawner, p: Peripherals) {
+    let flash = Flash::unlock(p.FLASH);
+    let mut flash = BlockingAsync::new(flash);
+
+    let button = Input::new(p.PB2, Pull::Up);
+    let mut button = ExtiInput::new(button, p.EXTI2);
+
+    let mut led = Output::new(p.PB5, Level::Low, Speed::Low);
+
+    led.set_high();
+
+    let mut updater = FirmwareUpdater::default();
+    button.wait_for_falling_edge().await;
+    let mut offset = 0;
+    for chunk in APP_B.chunks(128) {
+        let mut buf: [u8; 128] = [0; 128];
+        buf[..chunk.len()].copy_from_slice(chunk);
+        updater
+            .write_firmware(offset, &buf, &mut flash, 128)
+            .await
+            .unwrap();
+        offset += chunk.len();
+    }
+
+    updater.mark_update(&mut flash).await.unwrap();
+    led.set_low();
+    Timer::after(Duration::from_secs(1)).await;
+    cortex_m::peripheral::SCB::sys_reset();
+}
diff --git a/examples/boot/stm32l1/src/bin/b.rs b/examples/boot/stm32l1/src/bin/b.rs
new file mode 100644
index 000000000..ed774fd70
--- /dev/null
+++ b/examples/boot/stm32l1/src/bin/b.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::Peripherals;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    let mut led = Output::new(p.PB6, Level::High, Speed::Low);
+
+    loop {
+        led.set_high();
+        Timer::after(Duration::from_millis(500)).await;
+
+        led.set_low();
+        Timer::after(Duration::from_millis(500)).await;
+    }
+}
diff --git a/examples/boot/stm32l4/.cargo/config.toml b/examples/boot/stm32l4/.cargo/config.toml
new file mode 100644
index 000000000..7b6c4c0ac
--- /dev/null
+++ b/examples/boot/stm32l4/.cargo/config.toml
@@ -0,0 +1,6 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# replace your chip as listed in `probe-run --list-chips`
+runner = "probe-run --chip STM32L475VG"
+
+[build]
+target = "thumbv7em-none-eabihf"
diff --git a/examples/boot/stm32l4/Cargo.toml b/examples/boot/stm32l4/Cargo.toml
new file mode 100644
index 000000000..53424a666
--- /dev/null
+++ b/examples/boot/stm32l4/Cargo.toml
@@ -0,0 +1,26 @@
+[package]
+authors = ["Ulf Lilleengen <[email protected]>"]
+edition = "2018"
+name = "embassy-boot-stm32l4-examples"
+version = "0.1.0"
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../../../embassy", features = ["nightly"] }
+embassy-stm32 = { version = "0.1.0", path = "../../../embassy-stm32", features = ["unstable-traits", "nightly", "stm32l475vg", "time-driver-any", "exti"]  }
+embassy-boot-stm32 = { version = "0.1.0", path = "../../../embassy-boot/stm32" }
+embassy-traits = { version = "0.1.0", path = "../../../embassy-traits" }
+
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+panic-reset = { version = "0.1.1" }
+embedded-hal = { version = "0.2.6" }
+
+cortex-m = "0.7.3"
+cortex-m-rt = "0.7.0"
+
+[features]
+defmt = [
+      "dep:defmt",
+      "embassy-stm32/defmt",
+      "embassy-boot-stm32/defmt",
+]
diff --git a/examples/boot/stm32l4/README.md b/examples/boot/stm32l4/README.md
new file mode 100644
index 000000000..8966c2fb5
--- /dev/null
+++ b/examples/boot/stm32l4/README.md
@@ -0,0 +1,29 @@
+# Examples using bootloader
+
+Example for STM32L4 demonstrating the bootloader. The example consists of application binaries, 'a'
+which allows you to press a button to start the DFU process, and 'b' which is the updated
+application.
+
+
+## Prerequisites
+
+* `cargo-binutils`
+* `cargo-flash`
+* `embassy-boot-stm32`
+
+## Usage
+
+```
+# Flash bootloader
+cargo flash --manifest-path ../../../embassy-boot/stm32/Cargo.toml --release --features embassy-stm32/stm32l475vg --chip STM32L475VG
+# Build 'b'
+cargo build --release --bin b
+# Generate binary for 'b'
+cargo objcopy --release --bin b -- -O binary b.bin
+```
+
+# Flash `a` (which includes b.bin)
+
+```
+cargo flash --release --bin a --chip STM32L475VG
+```
diff --git a/examples/boot/stm32l4/build.rs b/examples/boot/stm32l4/build.rs
new file mode 100644
index 000000000..e1da69328
--- /dev/null
+++ b/examples/boot/stm32l4/build.rs
@@ -0,0 +1,37 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    if env::var("CARGO_FEATURE_DEFMT").is_ok() {
+        println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    }
+}
diff --git a/examples/boot/stm32l4/memory.x b/examples/boot/stm32l4/memory.x
new file mode 100644
index 000000000..14b2a2c9f
--- /dev/null
+++ b/examples/boot/stm32l4/memory.x
@@ -0,0 +1,15 @@
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  BOOTLOADER                        : ORIGIN = 0x08000000, LENGTH = 24K
+  BOOTLOADER_STATE                  : ORIGIN = 0x08006000, LENGTH = 4K
+  FLASH                             : ORIGIN = 0x08008000, LENGTH = 32K
+  DFU                               : ORIGIN = 0x08010000, LENGTH = 36K
+  RAM                         (rwx) : ORIGIN = 0x20000008, LENGTH = 32K
+}
+
+__bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+__bootloader_state_end = ORIGIN(BOOTLOADER_STATE) + LENGTH(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+
+__bootloader_dfu_start = ORIGIN(DFU) - ORIGIN(BOOTLOADER);
+__bootloader_dfu_end = ORIGIN(DFU) + LENGTH(DFU) - ORIGIN(BOOTLOADER);
diff --git a/examples/boot/stm32l4/src/bin/a.rs b/examples/boot/stm32l4/src/bin/a.rs
new file mode 100644
index 000000000..a5a9e2302
--- /dev/null
+++ b/examples/boot/stm32l4/src/bin/a.rs
@@ -0,0 +1,44 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy_boot_stm32::FirmwareUpdater;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
+use embassy_stm32::Peripherals;
+use embassy_traits::adapter::BlockingAsync;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+static APP_B: &[u8] = include_bytes!("../../b.bin");
+
+#[embassy::main]
+async fn main(_s: embassy::executor::Spawner, p: Peripherals) {
+    let flash = Flash::unlock(p.FLASH);
+    let mut flash = BlockingAsync::new(flash);
+
+    let button = Input::new(p.PC13, Pull::Up);
+    let mut button = ExtiInput::new(button, p.EXTI13);
+
+    let mut led = Output::new(p.PB14, Level::Low, Speed::Low);
+    led.set_high();
+
+    let mut updater = FirmwareUpdater::default();
+    button.wait_for_falling_edge().await;
+    let mut offset = 0;
+    for chunk in APP_B.chunks(2048) {
+        let mut buf: [u8; 2048] = [0; 2048];
+        buf[..chunk.len()].copy_from_slice(chunk);
+        updater
+            .write_firmware(offset, &buf, &mut flash, 2048)
+            .await
+            .unwrap();
+        offset += chunk.len();
+    }
+    updater.mark_update(&mut flash).await.unwrap();
+    led.set_low();
+    cortex_m::peripheral::SCB::sys_reset();
+}
diff --git a/examples/boot/stm32l4/src/bin/b.rs b/examples/boot/stm32l4/src/bin/b.rs
new file mode 100644
index 000000000..814275988
--- /dev/null
+++ b/examples/boot/stm32l4/src/bin/b.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::Peripherals;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    let mut led = Output::new(p.PA5, Level::High, Speed::Low);
+
+    loop {
+        led.set_high();
+        Timer::after(Duration::from_millis(500)).await;
+
+        led.set_low();
+        Timer::after(Duration::from_millis(500)).await;
+    }
+}
diff --git a/examples/boot/stm32wl/.cargo/config.toml b/examples/boot/stm32wl/.cargo/config.toml
new file mode 100644
index 000000000..60076e06b
--- /dev/null
+++ b/examples/boot/stm32wl/.cargo/config.toml
@@ -0,0 +1,6 @@
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# replace your chip as listed in `probe-run --list-chips`
+runner = "probe-run --chip STM32WLE5JCIx"
+
+[build]
+target = "thumbv7em-none-eabihf"
diff --git a/examples/boot/stm32wl/Cargo.toml b/examples/boot/stm32wl/Cargo.toml
new file mode 100644
index 000000000..fb64886e6
--- /dev/null
+++ b/examples/boot/stm32wl/Cargo.toml
@@ -0,0 +1,26 @@
+[package]
+authors = ["Ulf Lilleengen <[email protected]>"]
+edition = "2018"
+name = "embassy-boot-stm32wl-examples"
+version = "0.1.0"
+
+[dependencies]
+embassy = { version = "0.1.0", path = "../../../embassy", features = ["nightly"] }
+embassy-stm32 = { version = "0.1.0", path = "../../../embassy-stm32", features = ["unstable-traits", "nightly", "stm32wl55jc-cm4", "time-driver-any", "exti"]  }
+embassy-boot-stm32 = { version = "0.1.0", path = "../../../embassy-boot/stm32" }
+embassy-traits = { version = "0.1.0", path = "../../../embassy-traits" }
+
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+panic-reset = { version = "0.1.1" }
+embedded-hal = { version = "0.2.6" }
+
+cortex-m = "0.7.3"
+cortex-m-rt = "0.7.0"
+
+[features]
+defmt = [
+      "dep:defmt",
+      "embassy-stm32/defmt",
+      "embassy-boot-stm32/defmt",
+]
diff --git a/examples/boot/stm32wl/README.md b/examples/boot/stm32wl/README.md
new file mode 100644
index 000000000..edcdacf91
--- /dev/null
+++ b/examples/boot/stm32wl/README.md
@@ -0,0 +1,29 @@
+# Examples using bootloader
+
+Example for STM32WL demonstrating the bootloader. The example consists of application binaries, 'a'
+which allows you to press a button to start the DFU process, and 'b' which is the updated
+application.
+
+
+## Prerequisites
+
+* `cargo-binutils`
+* `cargo-flash`
+* `embassy-boot-stm32`
+
+## Usage
+
+```
+# Flash bootloader
+cargo flash --manifest-path ../../../embassy-boot/stm32/Cargo.toml --release --features embassy-stm32/stm32wl55jc-cm4 --chip STM32WLE5JCIx
+# Build 'b'
+cargo build --release --bin b
+# Generate binary for 'b'
+cargo objcopy --release --bin b -- -O binary b.bin
+```
+
+# Flash `a` (which includes b.bin)
+
+```
+cargo flash --release --bin a --chip STM32WLE5JCIx
+```
diff --git a/examples/boot/stm32wl/build.rs b/examples/boot/stm32wl/build.rs
new file mode 100644
index 000000000..e1da69328
--- /dev/null
+++ b/examples/boot/stm32wl/build.rs
@@ -0,0 +1,37 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    if env::var("CARGO_FEATURE_DEFMT").is_ok() {
+        println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    }
+}
diff --git a/examples/boot/stm32wl/memory.x b/examples/boot/stm32wl/memory.x
new file mode 100644
index 000000000..14b2a2c9f
--- /dev/null
+++ b/examples/boot/stm32wl/memory.x
@@ -0,0 +1,15 @@
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  BOOTLOADER                        : ORIGIN = 0x08000000, LENGTH = 24K
+  BOOTLOADER_STATE                  : ORIGIN = 0x08006000, LENGTH = 4K
+  FLASH                             : ORIGIN = 0x08008000, LENGTH = 32K
+  DFU                               : ORIGIN = 0x08010000, LENGTH = 36K
+  RAM                         (rwx) : ORIGIN = 0x20000008, LENGTH = 32K
+}
+
+__bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+__bootloader_state_end = ORIGIN(BOOTLOADER_STATE) + LENGTH(BOOTLOADER_STATE) - ORIGIN(BOOTLOADER);
+
+__bootloader_dfu_start = ORIGIN(DFU) - ORIGIN(BOOTLOADER);
+__bootloader_dfu_end = ORIGIN(DFU) + LENGTH(DFU) - ORIGIN(BOOTLOADER);
diff --git a/examples/boot/stm32wl/src/bin/a.rs b/examples/boot/stm32wl/src/bin/a.rs
new file mode 100644
index 000000000..d01a72f2d
--- /dev/null
+++ b/examples/boot/stm32wl/src/bin/a.rs
@@ -0,0 +1,47 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy_boot_stm32::FirmwareUpdater;
+use embassy_stm32::exti::ExtiInput;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
+use embassy_stm32::Peripherals;
+use embassy_traits::adapter::BlockingAsync;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+static APP_B: &[u8] = include_bytes!("../../b.bin");
+
+#[embassy::main]
+async fn main(_s: embassy::executor::Spawner, p: Peripherals) {
+    let flash = Flash::unlock(p.FLASH);
+    let mut flash = BlockingAsync::new(flash);
+
+    let button = Input::new(p.PA0, Pull::Up);
+    let mut button = ExtiInput::new(button, p.EXTI0);
+
+    let mut led = Output::new(p.PB9, Level::Low, Speed::Low);
+    led.set_high();
+
+    let mut updater = FirmwareUpdater::default();
+    button.wait_for_falling_edge().await;
+    //defmt::info!("Starting update");
+    let mut offset = 0;
+    for chunk in APP_B.chunks(2048) {
+        let mut buf: [u8; 2048] = [0; 2048];
+        buf[..chunk.len()].copy_from_slice(chunk);
+        //        defmt::info!("Writing chunk at 0x{:x}", offset);
+        updater
+            .write_firmware(offset, &buf, &mut flash, 2048)
+            .await
+            .unwrap();
+        offset += chunk.len();
+    }
+    updater.mark_update(&mut flash).await.unwrap();
+    //defmt::info!("Marked as updated");
+    led.set_low();
+    cortex_m::peripheral::SCB::sys_reset();
+}
diff --git a/examples/boot/stm32wl/src/bin/b.rs b/examples/boot/stm32wl/src/bin/b.rs
new file mode 100644
index 000000000..ffe15b661
--- /dev/null
+++ b/examples/boot/stm32wl/src/bin/b.rs
@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::Peripherals;
+use panic_reset as _;
+
+#[cfg(feature = "defmt-rtt")]
+use defmt_rtt::*;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    let mut led = Output::new(p.PB15, Level::High, Speed::Low);
+
+    loop {
+        led.set_high();
+        Timer::after(Duration::from_millis(500)).await;
+
+        led.set_low();
+        Timer::after(Duration::from_millis(500)).await;
+    }
+}
diff --git a/examples/stm32l0/Cargo.toml b/examples/stm32l0/Cargo.toml
index 0b21f6742..1cdb2f374 100644
--- a/examples/stm32l0/Cargo.toml
+++ b/examples/stm32l0/Cargo.toml
@@ -21,6 +21,8 @@ lorawan = { version = "0.7.1", default-features = false, features = ["default-cr
 defmt = "0.3"
 defmt-rtt = "0.3"
 
+embedded-storage = "0.3.0"
+
 cortex-m = "0.7.3"
 cortex-m-rt = "0.7.0"
 panic-probe = { version = "0.3", features = ["print-defmt"] }
diff --git a/examples/stm32l0/src/bin/flash.rs b/examples/stm32l0/src/bin/flash.rs
new file mode 100644
index 000000000..c2ccb5b69
--- /dev/null
+++ b/examples/stm32l0/src/bin/flash.rs
@@ -0,0 +1,43 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{info, unwrap};
+use embassy::executor::Spawner;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::Peripherals;
+use embedded_storage::nor_flash::{NorFlash, ReadNorFlash};
+
+use defmt_rtt as _; // global logger
+use panic_probe as _;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    info!("Hello Flash!");
+
+    const ADDR: u32 = 0x26000;
+
+    let mut f = Flash::unlock(p.FLASH);
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+
+    info!("Erasing...");
+    unwrap!(f.erase(ADDR, ADDR + 128));
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read after erase: {=[u8]:x}", buf);
+
+    info!("Writing...");
+    unwrap!(f.write(ADDR, &[1, 2, 3, 4, 5, 6, 7, 8]));
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+    assert_eq!(&buf[..], &[1, 2, 3, 4, 5, 6, 7, 8]);
+}
diff --git a/examples/stm32l1/Cargo.toml b/examples/stm32l1/Cargo.toml
index a7a6c228e..ce6b07729 100644
--- a/examples/stm32l1/Cargo.toml
+++ b/examples/stm32l1/Cargo.toml
@@ -18,3 +18,4 @@ embedded-hal = "0.2.6"
 panic-probe = { version = "0.3", features = ["print-defmt"] }
 futures = { version = "0.3.17", default-features = false, features = ["async-await"] }
 heapless = { version = "0.7.5", default-features = false }
+embedded-storage = "0.3.0"
diff --git a/examples/stm32l1/src/bin/flash.rs b/examples/stm32l1/src/bin/flash.rs
new file mode 100644
index 000000000..eea838cba
--- /dev/null
+++ b/examples/stm32l1/src/bin/flash.rs
@@ -0,0 +1,43 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{info, unwrap};
+use embassy::executor::Spawner;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::Peripherals;
+use embedded_storage::nor_flash::{NorFlash, ReadNorFlash};
+
+use defmt_rtt as _; // global logger
+use panic_probe as _;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    info!("Hello Flash!");
+
+    const ADDR: u32 = 0x26000;
+
+    let mut f = Flash::unlock(p.FLASH);
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+
+    info!("Erasing...");
+    unwrap!(f.erase(ADDR, ADDR + 256));
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read after erase: {=[u8]:x}", buf);
+
+    info!("Writing...");
+    unwrap!(f.write(ADDR, &[1, 2, 3, 4, 5, 6, 7, 8]));
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+    assert_eq!(&buf[..], &[1, 2, 3, 4, 5, 6, 7, 8]);
+}
diff --git a/examples/stm32wl/Cargo.toml b/examples/stm32wl/Cargo.toml
index 919104b01..01f317039 100644
--- a/examples/stm32wl/Cargo.toml
+++ b/examples/stm32wl/Cargo.toml
@@ -8,7 +8,7 @@ resolver = "2"
 [dependencies]
 embassy = { version = "0.1.0", path = "../../embassy", features = ["defmt", "defmt-timestamp-uptime"] }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "stm32wl55jc-cm4", "time-driver-any", "memory-x", "subghz", "unstable-pac", "exti"]  }
-embassy-lora = { version = "0.1.0", path = "../../embassy-lora", features = ["stm32wl", "time"] }
+embassy-lora = { version = "0.1.0", path = "../../embassy-lora", features = ["stm32wl", "time", "defmt"] }
 
 lorawan-device = { version = "0.7.1", default-features = false, features = ["async"] }
 lorawan = { version = "0.7.1", default-features = false, features = ["default-crypto"] }
@@ -19,6 +19,7 @@ defmt-rtt = "0.3"
 cortex-m = "0.7.3"
 cortex-m-rt = "0.7.0"
 embedded-hal = "0.2.6"
+embedded-storage = "0.3.0"
 panic-probe = { version = "0.3", features = ["print-defmt"] }
 futures = { version = "0.3.17", default-features = false, features = ["async-await"] }
 heapless = { version = "0.7.5", default-features = false }
diff --git a/examples/stm32wl/src/bin/flash.rs b/examples/stm32wl/src/bin/flash.rs
new file mode 100644
index 000000000..f84818224
--- /dev/null
+++ b/examples/stm32wl/src/bin/flash.rs
@@ -0,0 +1,43 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{info, unwrap};
+use embassy::executor::Spawner;
+use embassy_stm32::flash::Flash;
+use embassy_stm32::Peripherals;
+use embedded_storage::nor_flash::{NorFlash, ReadNorFlash};
+
+use defmt_rtt as _; // global logger
+use panic_probe as _;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    info!("Hello Flash!");
+
+    const ADDR: u32 = 0x36000;
+
+    let mut f = Flash::unlock(p.FLASH);
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+
+    info!("Erasing...");
+    unwrap!(f.erase(ADDR, ADDR + 2048));
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+
+    info!("Writing...");
+    unwrap!(f.write(ADDR, &[1, 2, 3, 4, 5, 6, 7, 8]));
+
+    info!("Reading...");
+    let mut buf = [0u8; 8];
+    unwrap!(f.read(ADDR, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+    assert_eq!(&buf[..], &[1, 2, 3, 4, 5, 6, 7, 8]);
+}
diff --git a/stm32-data b/stm32-data
-Subproject 472ee98e8fdb11312392e47b16568c9d02fe654
+Subproject b71707e525e336f0afb9a74f3c436d3dd540ffc
diff --git a/stm32-metapac-gen/src/data.rs b/stm32-metapac-gen/src/data.rs
index a74c60ac0..17eccfe9a 100644
--- a/stm32-metapac-gen/src/data.rs
+++ b/stm32-metapac-gen/src/data.rs
@@ -16,6 +16,14 @@ pub struct MemoryRegion {
     pub kind: MemoryRegionKind,
     pub address: u32,
     pub size: u32,
+    pub settings: Option<FlashSettings>,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone, Deserialize)]
+pub struct FlashSettings {
+    pub erase_size: u32,
+    pub write_size: u32,
+    pub erase_value: u8,
 }
 
 #[derive(Debug, Eq, PartialEq, Clone, Deserialize)]
diff --git a/stm32-metapac-gen/src/lib.rs b/stm32-metapac-gen/src/lib.rs
index c959e1a61..f5d61ca31 100644
--- a/stm32-metapac-gen/src/lib.rs
+++ b/stm32-metapac-gen/src/lib.rs
@@ -129,6 +129,40 @@ impl Gen {
         )
         .unwrap();
 
+        let flash = chip.memory.iter().find(|r| r.name == "BANK_1").unwrap();
+        write!(
+            &mut extra,
+            "pub const FLASH_BASE: usize = {};\n",
+            flash.address,
+        )
+        .unwrap();
+        write!(
+            &mut extra,
+            "pub const FLASH_SIZE: usize = {};\n",
+            flash.size,
+        )
+        .unwrap();
+        if let Some(settings) = &flash.settings {
+            write!(
+                &mut extra,
+                "pub const ERASE_SIZE: usize = {};\n",
+                settings.erase_size,
+            )
+            .unwrap();
+            write!(
+                &mut extra,
+                "pub const WRITE_SIZE: usize = {};\n",
+                settings.write_size,
+            )
+            .unwrap();
+            write!(
+                &mut extra,
+                "pub const ERASE_VALUE: u8 = {};\n",
+                settings.erase_value,
+            )
+            .unwrap();
+        }
+
         // Cleanups!
         transform::sort::Sort {}.run(&mut ir).unwrap();
         transform::Sanitize {}.run(&mut ir).unwrap();
diff --git a/stm32-metapac/src/metadata.rs b/stm32-metapac/src/metadata.rs
index 23b759f6c..d05830e94 100644
--- a/stm32-metapac/src/metadata.rs
+++ b/stm32-metapac/src/metadata.rs
@@ -15,6 +15,14 @@ pub struct MemoryRegion {
     pub kind: MemoryRegionKind,
     pub address: u32,
     pub size: u32,
+    pub settings: Option<FlashSettings>,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct FlashSettings {
+    pub erase_size: u32,
+    pub write_size: u32,
+    pub erase_value: u8,
 }
 
 #[derive(Debug, Eq, PartialEq, Clone)]