diff --git a/down-the-stack/dk_template/src/lib_solution.rs b/down-the-stack/dk_template/src/lib_solution.rs
new file mode 100644
index 0000000..5884013
--- /dev/null
+++ b/down-the-stack/dk_template/src/lib_solution.rs
@@ -0,0 +1,299 @@
+//! Hardware Abstraction Layer (HAL) for the nRF52840 Development Kit
+
+#![deny(missing_docs)]
+#![deny(warnings)]
+#![no_std]
+
+use core::{
+    ops,
+    fmt,
+    sync::atomic::{self, Ordering},
+    time::Duration,
+};
+
+use cortex_m::asm;
+use embedded_hal::digital::v2::{OutputPin as _, StatefulOutputPin};
+pub use hal::pac::{
+    UARTE1, uarte0::{
+        baudrate::BAUDRATE_A as Baudrate, config::PARITY_A as Parity}};
+use hal::{
+    gpio::{p0, Level, Output, Input, PullUp, Pin, Port, PushPull},
+    timer::OneShot, prelude::InputPin,
+};
+
+use defmt;
+use defmt_rtt as _; // global logger
+
+/// Components on the board
+pub struct Board {
+    /// LEDs
+    pub leds: Leds,
+    // --- Exercise --- 🔽
+    /// Buttons
+    pub buttons: Buttons,
+    // --- Exercise --- 🔼 
+    /// Timer
+    pub timer: Timer,
+    // --- Exercise --- 🔽
+    /// uarte interface
+    pub uarte: Uarte,
+    // --- Exercise --- 🔼 
+}
+
+/// All LEDs on the board
+pub struct Leds {
+    /// LED1: pin P0.13, green LED
+    pub led_1: Led,
+    /// LED2: pin P0.14, green LED
+    pub led_2: Led,
+    /// LED3: pin P0.15, green LED
+    pub led_3: Led,
+    /// LED4: pin P0.16, green LED
+    pub led_4: Led,
+}
+
+/// A single LED
+pub struct Led {
+    inner: Pin<Output<PushPull>>,
+}
+
+impl Led {
+    /// Turns on the LED
+    pub fn on(&mut self) {
+        defmt::trace!(
+            "setting P{}.{} low (LED on)",
+            port_as_char(&self.inner.port()),
+            self.inner.pin()
+        );
+
+        // NOTE this operations returns a `Result` but never returns the `Err` variant
+        let _ = self.inner.set_low();
+    }
+
+    /// Turns off the LED
+    pub fn off(&mut self) {
+        defmt::trace!(
+            "setting P{}.{} high (LED off)",
+            port_as_char(&self.inner.port()),
+            self.inner.pin()
+        );
+
+        // NOTE this operations returns a `Result` but never returns the `Err` variant
+        let _ = self.inner.set_high();
+    }
+
+    /// Returns `true` if the LED is in the OFF state
+    pub fn is_off(&self) -> bool {
+        self.inner.is_set_high() == Ok(true)
+    }
+
+    /// Returns `true` if the LED is in the ON state
+    pub fn is_on(&self) -> bool {
+        !self.is_off()
+    }
+
+    /// Toggles the state (on/off) of the LED
+    pub fn toggle(&mut self) {
+        if self.is_off() {
+            self.on();
+        } else {
+            self.off()
+        }
+    }
+}
+// --- Exercise ---  🔽
+/// All buttons on the board
+pub struct Buttons {
+    /// BUTTON1: pin P0.11, green LED
+    pub b_1: Button,
+    /// BUTTON2: pin P0.12, green LED
+    pub b_2: Button,
+    /// BUTTON3: pin P0.24, green LED
+    pub b_3: Button,
+    /// BUTTON4: pin P0.25, green LED
+    pub b_4: Button,
+}
+
+/// A single button
+pub struct Button {
+    inner: Pin<Input<PullUp>>,
+}
+
+impl Button {
+    /// returns true if button is pushed 
+    pub fn is_pushed(&self) -> bool {
+        self.inner.is_low() == Ok(true)
+    }
+}
+// --- Exercise --- 🔼 
+
+/// A timer for creating blocking delays
+pub struct Timer {
+    inner: hal::Timer<hal::pac::TIMER0, OneShot>,
+}
+
+
+impl Timer {
+    /// Blocks program execution for at least the specified `duration`
+    pub fn wait(&mut self, duration: Duration) {
+        defmt::trace!("blocking for {:?} ...", duration);
+
+        // 1 cycle = 1 microsecond because the underlying HAL driver
+        // always sets the timer to 1 MHz.
+        const NANOS_IN_ONE_MICRO: u32 = 1_000;
+        let subsec_micros = duration.subsec_nanos() / NANOS_IN_ONE_MICRO;
+        if subsec_micros != 0 {
+            self.inner.delay(subsec_micros);
+        }
+
+        const MICROS_IN_ONE_SEC: u32 = 1_000_000;
+        // maximum number of seconds that fit in a single `delay` call without overflowing the `u32`
+        // argument
+        const MAX_SECS: u32 = u32::MAX / MICROS_IN_ONE_SEC;
+        let mut secs = duration.as_secs();
+        while secs != 0 {
+            let cycles = if secs > MAX_SECS as u64 {
+                secs -= MAX_SECS as u64;
+                MAX_SECS * MICROS_IN_ONE_SEC
+            } else {
+                let cycles = secs as u32 * MICROS_IN_ONE_SEC;
+                secs = 0;
+                cycles
+            };
+
+            self.inner.delay(cycles)
+        }
+
+        defmt::trace!("... DONE");
+    }
+}
+
+impl ops::Deref for Timer {
+    type Target = hal::Timer<hal::pac::TIMER0, OneShot>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl ops::DerefMut for Timer {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.inner
+    }
+}
+
+/// Uarte peripheral
+pub struct Uarte {
+    inner: hal::Uarte<hal::pac::UARTE0>,
+}
+
+impl fmt::Write for Uarte {
+
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        // Copy all data into an on-stack buffer so we never try to EasyDMA from
+        // flash.
+        let mut buf: [u8; 16] = [0; 16];
+        for block in s.as_bytes().chunks(16) {
+            buf[..block.len()].copy_from_slice(block);
+            self.inner.write(&buf[..block.len()]).map_err(|_| fmt::Error)?;
+        }
+
+        Ok(())
+    }
+}
+
+/// Initializes the board
+///
+/// This return an `Err`or if called more than once
+pub fn init() -> Result<Board, ()> {
+    if let Some(periph) = hal::pac::Peripherals::take() {
+
+        let pins = p0::Parts::new(periph.P0);
+
+        // NOTE LEDs turn on when the pin output level is low
+        let led_1 = pins.p0_13.degrade().into_push_pull_output(Level::High);
+        let led_2 = pins.p0_14.degrade().into_push_pull_output(Level::High);
+        let led_3 = pins.p0_15.degrade().into_push_pull_output(Level::High);
+        let led_4 = pins.p0_16.degrade().into_push_pull_output(Level::High);
+        
+        // --- Exercise --- 🔽
+        // Buttons
+        let b_1 = pins.p0_11.degrade().into_pullup_input();
+        let b_2 = pins.p0_12.degrade().into_pullup_input();
+        let b_3 = pins.p0_24.degrade().into_pullup_input();
+        let b_4 = pins.p0_25.degrade().into_pullup_input();
+        // --- Exercise --- 🔼 
+
+        defmt::debug!("I/O pins have been configured for digital output");
+
+        let timer = hal::Timer::new(periph.TIMER0);
+
+        // --- Exercise --- 🔽
+        // Uarte
+        let pins =  hal::uarte::Pins {
+            rxd: pins.p0_08.degrade().into_floating_input(),
+            txd: pins.p0_06.degrade().into_push_pull_output(Level::High),
+            cts: Some(pins.p0_07.degrade().into_floating_input()),
+            rts: Some(pins.p0_05.degrade().into_push_pull_output(Level::High)),
+        };
+       
+
+        let uarte = hal::uarte::Uarte::new(periph.UARTE0, pins, Parity::INCLUDED, Baudrate::BAUD115200);
+        // --- Exercise --- 🔼 
+
+        Ok(Board {
+            leds: Leds {
+                led_1: Led { inner: led_1 },
+                led_2: Led { inner: led_2 },
+                led_3: Led { inner: led_3 },
+                led_4: Led { inner: led_4 },
+            },
+
+            // --- Exercise --- 🔽
+            buttons: Buttons {
+                b_1: Button { inner: b_1},
+                b_2: Button { inner: b_2},
+                b_3: Button { inner: b_3},
+                b_4: Button { inner: b_4},
+            },
+            // --- Exercise --- 🔼 
+
+            timer: Timer { inner: timer },
+
+            // --- Exercise ---  🔽
+            uarte: Uarte { inner: uarte },
+            // --- Exercise --- 🔼 
+        })
+    } else {
+        Err(())
+    }
+}
+
+/// Exits the application when the program is executed through the `probe-run` Cargo runner
+pub fn exit() -> ! {
+    unsafe {
+        // turn off the USB D+ pull-up before pausing the device with a breakpoint
+        // this disconnects the nRF device from the USB host so the USB host won't attempt further
+        // USB communication (and see an unresponsive device). probe-run will also reset the nRF's
+        // USBD peripheral when it sees the device in a halted state which has the same effect as
+        // this line but that can take a while and the USB host may issue a power cycle of the USB
+        // port / hub / root in the meantime, which can bring down the probe and break probe-run
+        const USBD_USBPULLUP: *mut u32 = 0x4002_7504 as *mut u32;
+        USBD_USBPULLUP.write_volatile(0)
+    }
+    defmt::println!("`dk::exit()` called; exiting ...");
+    // force any pending memory operation to complete before the BKPT instruction that follows
+    atomic::compiler_fence(Ordering::SeqCst);
+    loop {
+        asm::bkpt()
+    }
+}
+
+// Helper functions
+
+fn port_as_char(port: &Port) -> char {
+    match port {
+        Port::Port0 => '0',
+        Port::Port1 => '1',
+    }
+}