diff --git a/common/Cargo.toml b/common/Cargo.toml
index fa02773..9b344b6 100644
--- a/common/Cargo.toml
+++ b/common/Cargo.toml
@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+serde = { version = "1.0.219", default-features = false, features = ["serde_derive", "derive"] }
diff --git a/common/src/lib.rs b/common/src/lib.rs
index b93cf3f..209b243 100644
--- a/common/src/lib.rs
+++ b/common/src/lib.rs
@@ -1,14 +1,8 @@
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
-}
+#![no_std]
+use serde::Deserialize;
 
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
+#[derive(Deserialize, Default)]
+pub struct Command {
+    pub left: f32,
+    pub right: f32,
 }
diff --git a/robot-controller/Cargo.lock b/robot-controller/Cargo.lock
index f5302f4..d1fb248 100644
--- a/robot-controller/Cargo.lock
+++ b/robot-controller/Cargo.lock
@@ -105,6 +105,13 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "common"
+version = "0.1.0"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "critical-section"
 version = "1.2.0"
@@ -238,6 +245,7 @@ version = "0.1.0"
 dependencies = [
  "arduino-hal",
  "avr-device",
+ "common",
  "embedded-hal 1.0.0",
  "nb 1.1.0",
  "panic-halt",
diff --git a/robot-controller/Cargo.toml b/robot-controller/Cargo.toml
index 6c2bb1c..e9e1993 100644
--- a/robot-controller/Cargo.toml
+++ b/robot-controller/Cargo.toml
@@ -18,6 +18,7 @@ embedded-hal = "1.0"
 avr-device = "0.7.0"
 serde = { version = "1.0.219", default-features = false, features = ["serde_derive", "derive"] }
 postcard = "1.1.2"
+common = { path = "../common" }
 
 [dependencies.arduino-hal]
 git = "https://github.com/rahix/avr-hal"
diff --git a/robot-controller/src/main.rs b/robot-controller/src/main.rs
index 509b889..215b5a6 100644
--- a/robot-controller/src/main.rs
+++ b/robot-controller/src/main.rs
@@ -12,8 +12,8 @@ use arduino_hal::pac::USART0;
 use arduino_hal::port::mode::*;
 use arduino_hal::prelude::*;
 use avr_device::interrupt::{self, Mutex};
+use common::Command;
 use panic_halt as _;
-use serde::Deserialize;
 
 fn shift_out(data_pin: &mut Pin<Output, PB0>, clock_pin: &mut Pin<Output, PD4>, data: &u8) {
     for i in 0..8 {
@@ -157,12 +157,6 @@ fn main() -> ! {
     }
 }
 
-#[derive(Deserialize, Default)]
-struct Command {
-    left: f32,
-    right: f32,
-}
-
 fn decode_command() -> Command {
     let mut input = interrupt::free(|cs| {
         INPUT_LINE.borrow(cs).borrow().clone()