diff --git a/firmware/Cargo.lock b/firmware/Cargo.lock
index f835f10..701cf53 100644
--- a/firmware/Cargo.lock
+++ b/firmware/Cargo.lock
@@ -271,6 +271,7 @@ dependencies = [
  "defmt 0.3.100",
  "defmt-rtt",
  "embedded-hal",
+ "nb 1.1.0",
  "panic-halt",
  "stm32f0xx-hal",
 ]
diff --git a/firmware/Cargo.toml b/firmware/Cargo.toml
index c0e8bc1..1bf7026 100644
--- a/firmware/Cargo.toml
+++ b/firmware/Cargo.toml
@@ -7,9 +7,10 @@ version = "0.1.0"
 cortex-m = { version = "0.7", features = ["inline-asm", "critical-section-single-core"] }
 cortex-m-rt = "0.7"
 critical-section = "1"
-stm32f0xx-hal = { version = "0.18", features = ["stm32f042", "rt"] }
 embedded-hal = "0.2"
+nb = "1"
 panic-halt = "0.2"
+stm32f0xx-hal = { version = "0.18", features = ["stm32f042", "rt"] }
 
 # For debugging and logging
 defmt = "0.3"
diff --git a/firmware/src/main.rs b/firmware/src/main.rs
index c668249..39fcfbb 100644
--- a/firmware/src/main.rs
+++ b/firmware/src/main.rs
@@ -3,8 +3,13 @@
 
 use panic_halt as _;
 use cortex_m_rt::entry;
-use stm32f0xx_hal::{
-    delay::Delay, prelude::*, stm32
+use stm32f0xx_hal::serial::Error;
+use stm32f0xx_hal as hal;
+use hal::prelude::*;
+use hal::stm32;
+use hal::{
+    delay::Delay,
+    serial::Serial,
 };
 
 struct Bus {
@@ -33,7 +38,7 @@ fn main() -> ! {
         .sysclk(48.mhz())
         .pclk(24.mhz())
         .freeze(&mut dp.FLASH);
-    
+
     // Set up delay provider
     let mut delay = Delay::new(cp.SYST, &rcc);
     
@@ -55,28 +60,46 @@ fn main() -> ! {
             pb7: gpiob.pb7.into_push_pull_output(cs),
         }
     });
-    
+
+    let mut serial = cortex_m::interrupt::free(|cs| {
+        let tx = gpioa.pa9.into_alternate_af1(cs);
+        let rx = gpioa.pa10.into_alternate_af1(cs);
+        //dp.USART1.cr1.write(|w| w.uesm().enabled());
+        Serial::usart1(dp.USART1, (tx, rx), 31_250.bps(), &mut rcc)
+    });
+
     // Loop
     loop {
-        for ic in 0..=2 {
-            for i in 0..256 {
-                bus.output(ic, 1 << i, &mut delay);
-                delay.delay_ms(100u16);
+        use stm32f0xx_hal::serial::Error;
+        //type Error = nb::Error<stm32f0xx_hal::serial::Error>;
+        //use embedded_hal::serial::nb::Error;
+        match serial.read() {
+            Ok(_) => {
+                bus.led_button_1(&mut delay);
+            }
+            Err(nb::Error::WouldBlock) => {
+                bus.led_button_3(&mut delay);
+            }
+            Err(nb::Error::Other(Error::Framing)) => {
+                bus.led_button_2(&mut delay);
+            }
+            Err(nb::Error::Other(Error::Noise)) => {
+                bus.led_button_9(&mut delay);
+            }
+            Err(nb::Error::Other(_)) => {
+                bus.led_button_10(&mut delay);
             }
         }
+        delay.delay_ms(1000u16);
     }
 }
 
 impl Bus {
     fn output(&mut self, ic: u8, data: u8, delay: &mut Delay) {
         match ic {
-            0 => self.select(1, delay),
-            1 => self.select(0, delay),
-            2 => self.select(5, delay),
-
-            3 => self.select(1, delay),
-            10 => self.select(0, delay),
-            11 => self.select(5, delay),
+            0 | 3 => self.select(1, delay),
+            1 | 10 => self.select(0, delay),
+            2 | 11 => self.select(5, delay),
 
             _ => self.select(2, delay),
         }
@@ -89,14 +112,14 @@ impl Bus {
     }
 
     fn write(&mut self, data: u8) {
-        self.pb0.set_state((data & 0b00000001 != 0).into()).ok();
-        self.pb1.set_state((data & 0b00000010 != 0).into()).ok();
-        self.pb2.set_state((data & 0b00000100 != 0).into()).ok();
-        self.pb3.set_state((data & 0b00001000 != 0).into()).ok();
-        self.pb4.set_state((data & 0b00010000 != 0).into()).ok();
-        self.pb5.set_state((data & 0b00100000 != 0).into()).ok();
-        self.pb6.set_state((data & 0b01000000 != 0).into()).ok();
-        self.pb7.set_state((data & 0b10000000 != 0).into()).ok();
+        self.pb0.set_state((data & 0b_0000_0001 != 0).into()).ok();
+        self.pb1.set_state((data & 0b_0000_0010 != 0).into()).ok();
+        self.pb2.set_state((data & 0b_0000_0100 != 0).into()).ok();
+        self.pb3.set_state((data & 0b_0000_1000 != 0).into()).ok();
+        self.pb4.set_state((data & 0b_0001_0000 != 0).into()).ok();
+        self.pb5.set_state((data & 0b_0010_0000 != 0).into()).ok();
+        self.pb6.set_state((data & 0b_0100_0000 != 0).into()).ok();
+        self.pb7.set_state((data & 0b_1000_0000 != 0).into()).ok();
     }
 
     fn select_en(&mut self, enable: bool) {
@@ -196,4 +219,34 @@ impl Bus {
         delay.delay_ms(10u16);
         self.select_en.set_high().ok();
     }
+
+    fn led_button_1(&mut self, delay: &mut Delay) {
+        self.output(03, 0b1111_1011, delay);
+        self.output(10, 0b0001_0000, delay);
+        self.output(11, 0b0000_0000, delay);
+    }
+
+    fn led_button_2(&mut self, delay: &mut Delay) {
+        self.output(03, 0b1111_1101, delay);
+        self.output(10, 0b0001_0000, delay);
+        self.output(11, 0b0000_0000, delay);
+    }
+
+    fn led_button_3(&mut self, delay: &mut Delay) {
+        self.output(03, 0b1111_1110, delay);
+        self.output(10, 0b0001_0000, delay);
+        self.output(11, 0b0000_0000, delay);
+    }
+
+    fn led_button_9(&mut self, delay: &mut Delay) {
+        self.output(03, 0b1110_1111, delay);
+        self.output(10, 0b0001_0000, delay);
+        self.output(11, 0b0000_0000, delay);
+    }
+
+    fn led_button_10(&mut self, delay: &mut Delay) {
+        self.output(03, 0b1111_0111, delay);
+        self.output(10, 0b0001_0000, delay);
+        self.output(11, 0b0000_0000, delay);
+    }
 }
\ No newline at end of file