diff --git a/mdbook/src/09-led-compass/Cargo.toml b/mdbook/src/09-led-compass/Cargo.toml
index fc7bbe2..d35b513 100644
--- a/mdbook/src/09-led-compass/Cargo.toml
+++ b/mdbook/src/09-led-compass/Cargo.toml
@@ -6,10 +6,13 @@ edition = "2021"
 
 [dependencies]
 microbit-v2 = "0.15.0"
-cortex-m = "0.7.7"
 cortex-m-rt = "0.7.3"
 rtt-target = "0.5.0"
 panic-rtt-target = "0.1.3"
 lsm303agr = "1.1.0"
 libm = "0.2.8"
 embedded-hal = "1.0.0"
+
+[dependencies.cortex-m]
+version = "0.7.7"
+features = ["critical-section-single-core"]
diff --git a/mdbook/src/09-led-compass/src/calibration.rs b/mdbook/src/09-led-compass/src/calibration.rs
index 6bf13f4..c3360f7 100644
--- a/mdbook/src/09-led-compass/src/calibration.rs
+++ b/mdbook/src/09-led-compass/src/calibration.rs
@@ -1,8 +1,8 @@
 //! Translated from <https://github.com/lancaster-university/codal-microbit-v2/blob/006abf5566774fbcf674c0c7df27e8a9d20013de/source/MicroBitCompassCalibrator.cpp>
 
 use core::fmt::Debug;
-use embedded_hal::blocking::delay::DelayUs;
-use embedded_hal::blocking::i2c::{Write, WriteRead};
+use embedded_hal::i2c::I2c;
+use embedded_hal::delay::DelayNs;
 use libm::{fabsf, sqrtf};
 use lsm303agr::interface::I2cInterface;
 use lsm303agr::mode::MagContinuous;
@@ -43,8 +43,8 @@ pub fn calc_calibration<I, T, E>(
     timer: &mut T,
 ) -> Calibration
 where
-    T: DelayUs<u32>,
-    I: Write<Error = E> + WriteRead<Error = E>,
+    T: DelayNs,
+    I: I2c,
     E: Debug,
 {
     let data = get_data(sensor, display, timer);
@@ -57,8 +57,8 @@ fn get_data<I, T, E>(
     timer: &mut T,
 ) -> [Measurement; 25]
 where
-    T: DelayUs<u32>,
-    I: Write<Error = E> + WriteRead<Error = E>,
+    T: DelayNs,
+    I: I2c,
     E: Debug,
 {
     let mut leds = [
diff --git a/mdbook/src/10-punch-o-meter/Cargo.toml b/mdbook/src/10-punch-o-meter/Cargo.toml
index 0bbb5cd..981c1bc 100644
--- a/mdbook/src/10-punch-o-meter/Cargo.toml
+++ b/mdbook/src/10-punch-o-meter/Cargo.toml
@@ -6,9 +6,11 @@ edition = "2021"
 
 [dependencies]
 microbit-v2 = "0.15.0"
-cortex-m = "0.7.7"
 cortex-m-rt = "0.7.3"
 rtt-target = "0.5.0"
 panic-rtt-target = "0.1.3"
 lsm303agr = "1.1.0"
-nb = "1.1.0"
+
+[dependencies.cortex-m]
+version = "0.7.7"
+features = ["inline-asm", "critical-section-single-core"]
diff --git a/mdbook/src/10-punch-o-meter/build.rs b/mdbook/src/10-punch-o-meter/build.rs
deleted file mode 100644
index c8d8c91..0000000
--- a/mdbook/src/10-punch-o-meter/build.rs
+++ /dev/null
@@ -1,30 +0,0 @@
-//! 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,
-//! a rebuild of the application with new memory settings is ensured after updating `memory.x`.
-
-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");
-}
diff --git a/mdbook/src/10-punch-o-meter/memory.x b/mdbook/src/10-punch-o-meter/memory.x
deleted file mode 100644
index 9e2ab65..0000000
--- a/mdbook/src/10-punch-o-meter/memory.x
+++ /dev/null
@@ -1,6 +0,0 @@
-MEMORY
-{
-  /* NOTE K = KiBi = 1024 bytes */
-  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
-  RAM : ORIGIN = 0x20000000, LENGTH = 16K
-}
diff --git a/mdbook/src/10-punch-o-meter/src/main.rs b/mdbook/src/10-punch-o-meter/src/main.rs
index d14dc20..9a38836 100644
--- a/mdbook/src/10-punch-o-meter/src/main.rs
+++ b/mdbook/src/10-punch-o-meter/src/main.rs
@@ -2,14 +2,17 @@
 #![no_main]
 #![no_std]
 
+use cortex_m::asm::wfi;
 use cortex_m_rt::entry;
-use rtt_target::rtt_init_print;
 use panic_rtt_target as _;
+use rtt_target::rtt_init_print;
 
 #[entry]
 fn main() -> ! {
     rtt_init_print!();
     let _board = microbit::Board::take().unwrap();
 
-    loop {}
+    loop {
+        wfi();
+    }
 }