diff --git a/.cargo/config b/hangman/.cargo/config
similarity index 100%
rename from .cargo/config
rename to hangman/.cargo/config
diff --git a/Cargo.lock b/hangman/Cargo.lock
similarity index 99%
rename from Cargo.lock
rename to hangman/Cargo.lock
index 129b5a9..2afe5aa 100644
--- a/Cargo.lock
+++ b/hangman/Cargo.lock
@@ -710,6 +710,7 @@ dependencies = [
  "embedded-alloc",
  "embedded-storage",
  "embedded-storage-async",
+ "hangman-utils",
  "hex",
  "median",
  "nrf-softdevice",
@@ -723,6 +724,14 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "hangman-utils"
+version = "0.1.0"
+dependencies = [
+ "defmt",
+ "num-traits",
+]
+
 [[package]]
 name = "hash32"
 version = "0.2.1"
diff --git a/Cargo.toml b/hangman/Cargo.toml
similarity index 97%
rename from Cargo.toml
rename to hangman/Cargo.toml
index 7f16520..d28ae6c 100644
--- a/Cargo.toml
+++ b/hangman/Cargo.toml
@@ -26,6 +26,7 @@ embassy-usb = { version = "0.1", features = ["defmt"], optional = true}
 embedded-alloc = "0.5"
 embedded-storage = "0.3"
 embedded-storage-async = "0.4"
+hangman-utils = { path = "../hangman_utils" }
 hex = { version = "0.4", default-features = false }
 median = { version = "0.3", default-features = false }
 nrf-softdevice = { version = "0.1", features = ["s113", "ble-gatt-server", "ble-peripheral", "critical-section-impl", "defmt"] }
diff --git a/Embed.toml b/hangman/Embed.toml
similarity index 100%
rename from Embed.toml
rename to hangman/Embed.toml
diff --git a/build.rs b/hangman/build.rs
similarity index 100%
rename from build.rs
rename to hangman/build.rs
diff --git a/flash.sh b/hangman/flash.sh
similarity index 100%
rename from flash.sh
rename to hangman/flash.sh
diff --git a/memory.x b/hangman/memory.x
similarity index 100%
rename from memory.x
rename to hangman/memory.x
diff --git a/src/battery_voltage.rs b/hangman/src/battery_voltage.rs
similarity index 100%
rename from src/battery_voltage.rs
rename to hangman/src/battery_voltage.rs
diff --git a/src/bin/README.md b/hangman/src/bin/README.md
similarity index 100%
rename from src/bin/README.md
rename to hangman/src/bin/README.md
diff --git a/src/bin/blinky_p0.rs b/hangman/src/bin/blinky_p0.rs
similarity index 100%
rename from src/bin/blinky_p0.rs
rename to hangman/src/bin/blinky_p0.rs
diff --git a/src/bin/blinky_p1.rs b/hangman/src/bin/blinky_p1.rs
similarity index 100%
rename from src/bin/blinky_p1.rs
rename to hangman/src/bin/blinky_p1.rs
diff --git a/src/bin/calibration_p0.rs b/hangman/src/bin/calibration_p0.rs
similarity index 100%
rename from src/bin/calibration_p0.rs
rename to hangman/src/bin/calibration_p0.rs
diff --git a/src/bin/calibration_p1.rs b/hangman/src/bin/calibration_p1.rs
similarity index 100%
rename from src/bin/calibration_p1.rs
rename to hangman/src/bin/calibration_p1.rs
diff --git a/src/bin/dongle.rs b/hangman/src/bin/dongle.rs
similarity index 100%
rename from src/bin/dongle.rs
rename to hangman/src/bin/dongle.rs
diff --git a/src/bin/proto0_0.rs b/hangman/src/bin/proto0_0.rs
similarity index 100%
rename from src/bin/proto0_0.rs
rename to hangman/src/bin/proto0_0.rs
diff --git a/src/bin/proto1_0.rs b/hangman/src/bin/proto1_0.rs
similarity index 100%
rename from src/bin/proto1_0.rs
rename to hangman/src/bin/proto1_0.rs
diff --git a/src/ble/advertising.rs b/hangman/src/ble/advertising.rs
similarity index 100%
rename from src/ble/advertising.rs
rename to hangman/src/ble/advertising.rs
diff --git a/src/ble/gatt_server.rs b/hangman/src/ble/gatt_server.rs
similarity index 100%
rename from src/ble/gatt_server.rs
rename to hangman/src/ble/gatt_server.rs
diff --git a/src/ble/gatt_types.rs b/hangman/src/ble/gatt_types.rs
similarity index 100%
rename from src/ble/gatt_types.rs
rename to hangman/src/ble/gatt_types.rs
diff --git a/src/ble/mod.rs b/hangman/src/ble/mod.rs
similarity index 100%
rename from src/ble/mod.rs
rename to hangman/src/ble/mod.rs
diff --git a/src/ble/task.rs b/hangman/src/ble/task.rs
similarity index 100%
rename from src/ble/task.rs
rename to hangman/src/ble/task.rs
diff --git a/src/button.rs b/hangman/src/button.rs
similarity index 100%
rename from src/button.rs
rename to hangman/src/button.rs
diff --git a/src/console/board.rs b/hangman/src/console/board.rs
similarity index 100%
rename from src/console/board.rs
rename to hangman/src/console/board.rs
diff --git a/src/console/mod.rs b/hangman/src/console/mod.rs
similarity index 100%
rename from src/console/mod.rs
rename to hangman/src/console/mod.rs
diff --git a/src/console/task.rs b/hangman/src/console/task.rs
similarity index 100%
rename from src/console/task.rs
rename to hangman/src/console/task.rs
diff --git a/src/lib.rs b/hangman/src/lib.rs
similarity index 100%
rename from src/lib.rs
rename to hangman/src/lib.rs
diff --git a/src/nonvolatile.rs b/hangman/src/nonvolatile.rs
similarity index 94%
rename from src/nonvolatile.rs
rename to hangman/src/nonvolatile.rs
index 1baffb9..85f53d6 100644
--- a/src/nonvolatile.rs
+++ b/hangman/src/nonvolatile.rs
@@ -140,14 +140,3 @@ impl Nvm {
             .expect("Write to succeed");
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn addresses() {
-        // Ensure that all of the registers and 4-byte checksum can fit on our Flash page
-        assert!(4 * (RegisterRead::COUNT + 1) <= MAX_ADDR - MIN_ADDR);
-    }
-}
diff --git a/src/sleep.rs b/hangman/src/sleep.rs
similarity index 100%
rename from src/sleep.rs
rename to hangman/src/sleep.rs
diff --git a/hangman/src/util.rs b/hangman/src/util.rs
new file mode 100644
index 0000000..628826c
--- /dev/null
+++ b/hangman/src/util.rs
@@ -0,0 +1,29 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::pac;
+
+pub unsafe fn disable_all_gpio_sense() {
+    #[cfg(feature = "nrf52840")]
+    {
+        let p1 = unsafe { &(*pac::P1::ptr()) };
+        for cnf in &p1.pin_cnf {
+            cnf.modify(|_, w| w.sense().disabled());
+        }
+    }
+    let p0 = unsafe { &(*pac::P0::ptr()) };
+    for cnf in &p0.pin_cnf {
+        cnf.modify(|_, w| w.sense().disabled());
+    }
+}
diff --git a/src/weight/ads1230.rs b/hangman/src/weight/ads1230.rs
similarity index 98%
rename from src/weight/ads1230.rs
rename to hangman/src/weight/ads1230.rs
index 6eca457..e220423 100644
--- a/src/weight/ads1230.rs
+++ b/hangman/src/weight/ads1230.rs
@@ -14,7 +14,7 @@
 
 /// Ads1230 driver using embassy_nrf-friendly types
 use super::{Sample, SampleProducerMut};
-use crate::{blocking_hal::prelude::_embedded_hal_blocking_delay_DelayUs, util, SharedDelay};
+use crate::{blocking_hal::prelude::_embedded_hal_blocking_delay_DelayUs, SharedDelay};
 use embassy_nrf::gpio::{AnyPin, Input, Output};
 use embassy_time::Instant;
 use embassy_time::{Duration, Timer};
@@ -126,7 +126,7 @@ impl<'d> Ads1230<'d> {
             // The ADS1230 gives a 20-bit signed reading, which is initially stored in a u32 container.
             // Unsigned for sane shifting and 32-bit because there is no u20 Rust primitive. Convert it
             // to a signed integer so that it is interpreted correctly.
-            let value = util::convert_signed_to_i32::<20>(raw_reading);
+            let value = hangman_utils::convert_signed_to_i32::<20>(raw_reading);
             // HX711 sometimes spontaneously returns -1 (0xFFFFFF)
             if value == -1 && n_skips < 3 {
                 n_skips += 1;
diff --git a/src/weight/average.rs b/hangman/src/weight/average.rs
similarity index 100%
rename from src/weight/average.rs
rename to hangman/src/weight/average.rs
diff --git a/src/weight/calibrate.rs b/hangman/src/weight/calibrate.rs
similarity index 100%
rename from src/weight/calibrate.rs
rename to hangman/src/weight/calibrate.rs
diff --git a/src/weight/hx711.rs b/hangman/src/weight/hx711.rs
similarity index 97%
rename from src/weight/hx711.rs
rename to hangman/src/weight/hx711.rs
index 3e99283..f732275 100644
--- a/src/weight/hx711.rs
+++ b/hangman/src/weight/hx711.rs
@@ -14,7 +14,7 @@
 
 /// Hx711 driver using embassy_nrf-friendly types
 use super::{Sample, SampleProducerMut};
-use crate::{blocking_hal::prelude::_embedded_hal_blocking_delay_DelayUs, util, SharedDelay};
+use crate::{blocking_hal::prelude::_embedded_hal_blocking_delay_DelayUs, SharedDelay};
 use embassy_nrf::gpio::{AnyPin, Input, Output};
 use embassy_time::{Duration, Instant, Timer};
 
@@ -105,7 +105,7 @@ impl<'d> Hx711<'d> {
             // The HX711 gives a 24-bit signed reading, which is initially stored in a u32 container.
             // Unsigned for sane shifting and 32-bit because there is no u24 Rust primitive. Convert it
             // to a signed integer so that it is interpreted correctly.
-            let value = util::convert_signed_to_i32::<24>(raw_reading);
+            let value = hangman_utils::convert_signed_to_i32::<24>(raw_reading);
             // HX711 sometimes spontaneously returns -1 (0xFFFFFF)
             if value == -1 && n_skips < 3 {
                 n_skips += 1;
diff --git a/src/weight/median.rs b/hangman/src/weight/median.rs
similarity index 100%
rename from src/weight/median.rs
rename to hangman/src/weight/median.rs
diff --git a/src/weight/mod.rs b/hangman/src/weight/mod.rs
similarity index 99%
rename from src/weight/mod.rs
rename to hangman/src/weight/mod.rs
index a1fc3fe..f0767af 100644
--- a/src/weight/mod.rs
+++ b/hangman/src/weight/mod.rs
@@ -15,7 +15,6 @@
 pub mod ads1230;
 pub mod average;
 mod calibrate;
-mod factory_calibration;
 pub mod hx711;
 pub mod median;
 mod random;
diff --git a/src/weight/random.rs b/hangman/src/weight/random.rs
similarity index 100%
rename from src/weight/random.rs
rename to hangman/src/weight/random.rs
diff --git a/src/weight/tare.rs b/hangman/src/weight/tare.rs
similarity index 100%
rename from src/weight/tare.rs
rename to hangman/src/weight/tare.rs
diff --git a/src/weight/task.rs b/hangman/src/weight/task.rs
similarity index 95%
rename from src/weight/task.rs
rename to hangman/src/weight/task.rs
index d12a40b..6ea7523 100644
--- a/src/weight/task.rs
+++ b/hangman/src/weight/task.rs
@@ -13,7 +13,6 @@
 // limitations under the License.
 
 use super::calibrate::Calibrator;
-use super::factory_calibration::{self, CalPoint, TwoPoint};
 use super::tare::Tarer;
 #[cfg(feature = "nrf52832")]
 use super::Ads1230;
@@ -25,6 +24,7 @@ use crate::MeasureCommandReceiver;
 use embassy_sync::blocking_mutex::raw::NoopRawMutex;
 use embassy_sync::mutex::Mutex;
 use embassy_time::{Duration, Instant, Timer};
+use hangman_utils::two_point_cal::{self, CalPoint, TwoPoint};
 use nrf_softdevice::Softdevice;
 use static_cell::make_static;
 
@@ -51,7 +51,7 @@ struct MeasurementContext {
     calibrator: &'static SharedCalibrator,
     tarer: Tarer<&'static SharedCalibrator>,
     nvm: Nvm,
-    factory_cal: TwoPoint,
+    factory_cal: TwoPoint<RawReading>,
 }
 
 async fn handle_command(cmd: Command, context: &mut MeasurementContext, adc: &SharedAdc) {
@@ -113,11 +113,13 @@ async fn handle_command(cmd: Command, context: &mut MeasurementContext, adc: &Sh
             }
             let Sample { value, .. } = context.median.sample().await;
             let reading = filter.add_sample(value).unwrap();
-            context.factory_cal.add_point(CalPoint { weight, reading });
+            context.factory_cal.add_point(CalPoint {
+                expected_value: weight,
+                measured_value: reading,
+            });
         }
         Command::SaveCalibration => {
-            if let Some(factory_calibration::Constants { m, b }) =
-                context.factory_cal.get_cal_constants()
+            if let Some(two_point_cal::Constants { m, b }) = context.factory_cal.get_cal_constants()
             {
                 defmt::info!("New calibration: m = {=f32} b = {=i32}", m, b);
                 super::write_calibration(&mut context.nvm, m, b).await;
diff --git a/hangman_utils/Cargo.lock b/hangman_utils/Cargo.lock
new file mode 100644
index 0000000..442e4cb
--- /dev/null
+++ b/hangman_utils/Cargo.lock
@@ -0,0 +1,159 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "autocfg"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c4b4d0bd25bd0b74681c0ad21497610ce1b7c91b1022cd21c80c6fbdd9476b0"
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "defmt"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a99dd22262668b887121d4672af5a64b238f026099f1a2a1b322066c9ecfe9e0"
+dependencies = [
+ "bitflags",
+ "defmt-macros",
+]
+
+[[package]]
+name = "defmt-macros"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3a9f309eff1f79b3ebdf252954d90ae440599c26c2c553fe87a2d17195f2dcb"
+dependencies = [
+ "defmt-parser",
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.66",
+]
+
+[[package]]
+name = "defmt-parser"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ff4a5fefe330e8d7f31b16a318f9ce81000d8e35e69b93eae154d16d2278f70f"
+dependencies = [
+ "thiserror",
+]
+
+[[package]]
+name = "hangman-utils"
+version = "0.1.0"
+dependencies = [
+ "defmt",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.84"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec96c6a92621310b51366f1e28d05ef11489516e93be030060e5fc12024a49d6"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.36"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.66"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c42f3f41a2de00b01c0aaad383c5a45241efc8b2d1eda5661812fda5f3cdcff5"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "thiserror"
+version = "1.0.61"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c546c80d6be4bc6a00c0f01730c08df82eaa7a7a61f11d656526506112cc1709"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.61"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46c3384250002a6d5af4d114f2845d37b57521033f30d5c3f46c4d70e1197533"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.66",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
diff --git a/hangman_utils/Cargo.toml b/hangman_utils/Cargo.toml
new file mode 100644
index 0000000..d28d3d1
--- /dev/null
+++ b/hangman_utils/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "hangman-utils"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+defmt = { version = "0.3" }
+num-traits = { version = "0.2", default-features = false }
diff --git a/src/util.rs b/hangman_utils/src/lib.rs
similarity index 81%
rename from src/util.rs
rename to hangman_utils/src/lib.rs
index e28a77e..404e03b 100644
--- a/src/util.rs
+++ b/hangman_utils/src/lib.rs
@@ -1,4 +1,4 @@
-// Copyright 2023 Google LLC
+// Copyright 2024 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -12,21 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::pac;
+#![cfg_attr(not(test), no_std)]
+#![forbid(unsafe_op_in_unsafe_fn)]
 
-pub unsafe fn disable_all_gpio_sense() {
-    #[cfg(feature = "nrf52840")]
-    {
-        let p1 = unsafe { &(*pac::P1::ptr()) };
-        for cnf in &p1.pin_cnf {
-            cnf.modify(|_, w| w.sense().disabled());
-        }
-    }
-    let p0 = unsafe { &(*pac::P0::ptr()) };
-    for cnf in &p0.pin_cnf {
-        cnf.modify(|_, w| w.sense().disabled());
-    }
-}
+#[macro_use]
+pub mod log;
+pub mod two_point_cal;
 
 /// Convert a signed integer in a u32 container to a signed integer
 pub const fn convert_signed_to_i32<const BITS: u32>(mut input: u32) -> i32 {
@@ -38,8 +29,6 @@ pub const fn convert_signed_to_i32<const BITS: u32>(mut input: u32) -> i32 {
     input as i32
 }
 
-// TODO: figure out how to actually run these tests on host
-// I promise I ran them in the playground.
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/hangman_utils/src/log.rs b/hangman_utils/src/log.rs
new file mode 100644
index 0000000..b4068ef
--- /dev/null
+++ b/hangman_utils/src/log.rs
@@ -0,0 +1,58 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#[macro_export]
+macro_rules! trace {
+    ($($arg:tt)*) => {
+        if !cfg!(test) {
+            defmt::trace!($($arg)*);
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! debug {
+    ($($arg:tt)*) => {
+        if !cfg!(test) {
+            defmt::debug!($($arg)*);
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! info {
+    ($($arg:tt)*) => {
+        if !cfg!(test) {
+            defmt::info!($($arg)*);
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! warn {
+    ($($arg:tt)*) => {
+        if !cfg!(test) {
+            defmt::warn!($($arg)*);
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! error {
+    ($($arg:tt)*) => {
+        if !cfg!(test) {
+            defmt::error!($($arg)*);
+        }
+    };
+}
diff --git a/hangman_utils/src/two_point_cal.rs b/hangman_utils/src/two_point_cal.rs
new file mode 100644
index 0000000..5e85eea
--- /dev/null
+++ b/hangman_utils/src/two_point_cal.rs
@@ -0,0 +1,86 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use defmt::Format;
+use num_traits::PrimInt;
+
+#[derive(Copy, Clone, Format)]
+pub struct CalPoint<Reading> {
+    pub expected_value: f32,
+    pub measured_value: Reading,
+}
+
+#[derive(Copy, Clone, Default, Format)]
+pub struct TwoPoint<Reading> {
+    zero: Option<Reading>,
+    other: Option<CalPoint<Reading>>,
+}
+
+/// Calibration constants
+///
+/// weight = m * (reading - b)
+#[derive(Copy, Clone, Format)]
+pub struct Constants<Reading> {
+    pub m: f32,
+    pub b: Reading,
+}
+
+impl<Reading: PrimInt + Format> TwoPoint<Reading> {
+    pub fn add_point(&mut self, point: CalPoint<Reading>) {
+        crate::debug!("New calibration point: {}", point);
+        if point.expected_value == 0.0 {
+            self.zero = Some(point.measured_value);
+        } else {
+            self.other = Some(point);
+        }
+    }
+
+    pub fn get_cal_constants(&self) -> Option<Constants<Reading>> {
+        let other = self.other?;
+        let b = self.zero?;
+        if other.measured_value == b {
+            crate::error!("Attempted divide by zero");
+            return None;
+        }
+        let Some(denominator) = other.measured_value.checked_sub(&b) else {
+            crate::error!("Underflow: {} - {}", other.measured_value, b);
+            return None;
+        };
+        let m = other.expected_value / denominator.to_f32().unwrap();
+        Some(Constants { m, b })
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn calibrate() {
+        let mut cal = TwoPoint::default();
+        let zero = CalPoint {
+            expected_value: 0.0,
+            measured_value: 0x1234,
+        };
+        let other = CalPoint {
+            expected_value: 100.0,
+            measured_value: 0x4567,
+        };
+        cal.add_point(zero);
+        cal.add_point(other);
+        let Constants { m, b } = cal.get_cal_constants().unwrap();
+        assert_eq!((zero.measured_value - b) as f32 * m, zero.expected_value);
+        assert_eq!((other.measured_value - b) as f32 * m, other.expected_value);
+    }
+}
diff --git a/src/weight/factory_calibration.rs b/src/weight/factory_calibration.rs
deleted file mode 100644
index b1ef96e..0000000
--- a/src/weight/factory_calibration.rs
+++ /dev/null
@@ -1,81 +0,0 @@
-// Copyright 2023 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-use super::RawReading;
-use defmt::Format;
-
-#[derive(Copy, Clone, Format)]
-pub(crate) struct CalPoint {
-    pub(crate) weight: f32,
-    pub(crate) reading: RawReading,
-}
-
-#[derive(Copy, Clone, Default, Format)]
-pub(crate) struct TwoPoint {
-    zero: Option<RawReading>,
-    other: Option<CalPoint>,
-}
-
-/// Calibration constants
-///
-/// weight = m * (reading - b)
-#[derive(Copy, Clone, Format)]
-pub(crate) struct Constants {
-    pub(crate) m: f32,
-    pub(crate) b: RawReading,
-}
-
-impl TwoPoint {
-    pub(crate) fn add_point(&mut self, point: CalPoint) {
-        defmt::debug!("New calibration point: {}", point);
-        if point.weight == 0.0 {
-            self.zero = Some(point.reading);
-        } else {
-            self.other = Some(point);
-        }
-    }
-
-    pub(crate) fn get_cal_constants(&self) -> Option<Constants> {
-        let other = self.other?;
-        let b = self.zero?;
-        if other.reading - b == 0 {
-            defmt::warn!("Attempted divide by zero");
-            return None;
-        }
-        let m = other.weight / (other.reading - b) as f32;
-        Some(Constants { m, b })
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    fn calibrate() {
-        let mut cal = TwoPoint::default();
-        let zero = CalPoint {
-            weight: 0.0,
-            reading: 0x1234,
-        };
-        let other = CalPoint {
-            weight: 100.0,
-            reading: 0x4567,
-        };
-        cal.add_point(zero);
-        cal.add_point(other);
-        let Constants { m, b } = cal.get_cal_constants();
-        assert_eq!((zero.reading - b) as f32 * m, zero.weight);
-        assert_eq!((other.reading - b) as f32 * m, other.weight);
-    }
-}