diff --git a/flake.nix b/flake.nix
index f41a19a..fb42f67 100644
--- a/flake.nix
+++ b/flake.nix
@@ -207,6 +207,8 @@
           psrc = ./i2c;
           pbuildInputs = [
             (packages."x86_64-linux"."dio" { inherit gcc cflags; })
+            (packages."x86_64-linux"."shift-register" { inherit gcc cflags; })
+            (packages."x86_64-linux"."display" { inherit gcc cflags; })
           ];
         };
 
@@ -326,6 +328,32 @@
           ];
         };
 
+      packages."x86_64-linux"."lux-sensor_" = 
+      let
+        pkgs = import nixpkgs { system = "x86_64-linux"; };
+        avr = pkgs.pkgsCross.avr.buildPackages;
+      in packages."x86_64-linux"."lux-sensor" { gcc = "${avr.gcc}/bin/avr-gcc"; cflags = mcu_cflags atmega32u4; avr = true; };
+      packages."x86_64-linux"."lux-sensor" =
+        { gcc, cflags, avr }:
+        let
+          pkgs = import nixpkgs { system = "x86_64-linux"; };
+        in mkProgram {
+          pkgs = pkgs;
+          gcc = gcc;
+          cflags = cflags;
+          pname = "lux-sensor";
+          psrc = ./lux-sensor;
+          inherit avr;
+
+          pbuildInputs = [
+            (packages."x86_64-linux"."dio" { inherit gcc cflags; })
+            (packages."x86_64-linux"."display" { inherit gcc cflags; })
+            (packages."x86_64-linux"."i2c" { inherit gcc cflags; })
+            (packages."x86_64-linux"."shift-register" { inherit gcc cflags; })
+            (packages."x86_64-linux"."spi" { inherit gcc cflags; })
+          ];
+        };
+
       devShell."x86_64-linux" =
         let
           pkgs = import nixpkgs { system = "x86_64-linux"; };
diff --git a/i2c/i2c.c b/i2c/i2c.c
index 9fa5c1b..ff9eb2d 100644
--- a/i2c/i2c.c
+++ b/i2c/i2c.c
@@ -11,6 +11,8 @@ You should have received a copy of the GNU General Public License along with thi
 */
 
 #include <util/delay.h>
+#include <stdlib.h>
+#include <stdio.h>
 #include "i2c.h"
 
 void i2c_delay(void) {
@@ -18,10 +20,12 @@ void i2c_delay(void) {
 }
 
 inline void set_sda(i2c_bus_t *bus) {
+    bus->sda_state = true;
     dio_set_direction(&bus->sda, LINE_IN);
 }
 
 inline void clear_sda(i2c_bus_t *bus) {
+    bus->sda_state = false;
     dio_set_direction(&bus->sda, LINE_OUT);
 }
 
@@ -30,10 +34,12 @@ inline uint8_t read_sda(i2c_bus_t *bus) {
 }
 
 inline void set_scl(i2c_bus_t *bus) {
+    bus->scl_state = true;
     dio_set_direction(&bus->scl, LINE_IN);
 }
 
 inline void clear_scl(i2c_bus_t *bus) {
+    bus->scl_state = false;
     dio_set_direction(&bus->scl, LINE_OUT);
 }
 
@@ -41,18 +47,22 @@ inline uint8_t read_scl(i2c_bus_t *bus) {
     return dio_read(&bus->scl);
 }
 
-void i2c_init(i2c_bus_t *bus) {
+i2c_bus_t *i2c_init(dio_t clock, dio_t data) {
+    i2c_bus_t *bus = malloc(sizeof(i2c_bus_t));
+    bus->sda = data;
+    bus->scl = clock;
+
     dio_set(&bus->sda, 0);
     dio_set(&bus->scl, 0);
     set_sda(bus);
     set_scl(bus);
+
+    return bus;
 }
 
-void i2c_start_condition(i2c_bus_t *bus, i2c_error_e *error) {
+void i2c_start(i2c_bus_t *bus, i2c_error_e *error) {
     if (*error != i2c_ok) return;
 
-    // TODO: handle the restart state
-
     if (read_sda(bus) == 0) {
         *error = i2c_arbitration_lost;
         return;
@@ -63,9 +73,7 @@ void i2c_start_condition(i2c_bus_t *bus, i2c_error_e *error) {
     clear_scl(bus);
 }
 
-void i2c_end_condition(i2c_bus_t *bus, i2c_error_e *error) {
-    if (*error != i2c_ok) return;
-
+void i2c_end(i2c_bus_t *bus, i2c_error_e *error) {
     clear_sda(bus);
     i2c_delay();
 
@@ -91,13 +99,32 @@ void i2c_end_condition(i2c_bus_t *bus, i2c_error_e *error) {
     }
 }
 
+void i2c_restart(i2c_bus_t *bus, i2c_error_e *error) {
+    if (*error != i2c_ok) return;
+
+    set_sda(bus);
+    i2c_delay();
+    set_scl(bus);
+    int count = 0;
+    while (read_scl(bus) == 0) {
+        if (count == 5) {
+            *error = i2c_timeout;
+            return;
+        }
+        count++;
+        i2c_delay();
+    }
+
+    i2c_start(bus, error);
+}
+
 void i2c_write_bit(i2c_bus_t *bus, uint8_t value, i2c_error_e *error) {
     if (*error != i2c_ok) return;
 
     if (value) {
-        clear_sda(bus);
-    } else {
         set_sda(bus);
+    } else {
+        clear_sda(bus);
     }
     i2c_delay();
 
@@ -131,6 +158,7 @@ uint8_t i2c_read_bit(i2c_bus_t *bus, i2c_error_e *error) {
     i2c_delay();
 
     set_scl(bus);
+    i2c_delay();
     int count = 0;
     while (read_scl(bus) == 0) {
         if (count == 5) {
@@ -140,7 +168,6 @@ uint8_t i2c_read_bit(i2c_bus_t *bus, i2c_error_e *error) {
         count++;
         i2c_delay();
     }
-    i2c_delay();
 
     bit = read_sda(bus);
     clear_scl(bus);
@@ -164,21 +191,22 @@ void i2c_write_byte(i2c_bus_t *bus, uint8_t value, i2c_error_e *error) {
     return;
 }
 
-uint8_t i2c_read_byte(i2c_bus_t *bus, i2c_error_e *error) {
+uint8_t i2c_read_byte(i2c_bus_t *bus, bool final_nak, i2c_error_e *error) {
     if (*error != i2c_ok) return 0;
 
     uint8_t value = 0;
     for (int i = 0; i < 8; i++) {
-        value = value << 1 | i2c_read_bit(bus, error);
+        value = (value << 1) | i2c_read_bit(bus, error);
     }
 
-    if (*error != i2c_ok) {
-        i2c_error_e tmp_error;
-        i2c_write_bit(bus, 1, &tmp_error);
-        return 0;
+    if (*error != i2c_ok || final_nak) {
+        i2c_error_e tmp_status;
+        i2c_write_bit(bus, 1, &tmp_status);
+        return value;
     }
 
     i2c_write_bit(bus, 0, error);
+
     return value;
 }
 
@@ -195,3 +223,20 @@ void i2c_host_write(i2c_bus_t *bus, uint8_t address, uint8_t *data, size_t lengt
     }
 }
 */
+
+void i2c_status_to_string(i2c_error_e status, char msg[20]) {
+    switch (status) {
+        case i2c_ok:
+            snprintf(msg, 20, "ok");
+            break;
+        case i2c_arbitration_lost:
+            snprintf(msg, 20, "arbitration lost");
+            break;
+        case i2c_timeout:
+            snprintf(msg, 20, "timeout");
+            break;
+        case i2c_nak:
+            snprintf(msg, 20, "nak");
+            break;
+    }
+}
diff --git a/i2c/i2c.h b/i2c/i2c.h
index 2e2f4fb..5241a76 100644
--- a/i2c/i2c.h
+++ b/i2c/i2c.h
@@ -23,7 +23,10 @@ typedef enum {
 } i2c_error_e;
 
 typedef struct {
+    bool sda_state;
     dio_t sda;
+
+    bool scl_state;
     dio_t scl;
 } i2c_bus_t;
 
@@ -35,8 +38,17 @@ typedef struct {
 } i2c_client_t;
 */
 
-void i2c_init(i2c_bus_t *);
+i2c_bus_t * i2c_init(dio_t, dio_t);
+
+void i2c_start(i2c_bus_t *bus, i2c_error_e *error);
+void i2c_end(i2c_bus_t *bus, i2c_error_e *error);
+void i2c_restart(i2c_bus_t *bus, i2c_error_e *error);
+
+void i2c_write_byte(i2c_bus_t *bus, uint8_t value, i2c_error_e *error);
+uint8_t i2c_read_byte(i2c_bus_t *bus, bool final_nak, i2c_error_e *error);
 
 // void i2c_host_write(i2c_host_t *, uint8_t, uint8_t, size_t, i2c_error_e);
 
+void i2c_status_to_string(i2c_error_e status, char msg[20]);
+
 #endif
diff --git a/lux-sensor/main.c b/lux-sensor/main.c
new file mode 100644
index 0000000..5de9a48
--- /dev/null
+++ b/lux-sensor/main.c
@@ -0,0 +1,82 @@
+#include <dio.h>
+#include <i2c.h>
+#include <display.h>
+#include <stdio.h>
+
+int main(void) {
+    display_t display = {
+        .reg = {
+            .output         = { .ddr = &DDRF, .port = &PORTF, .pin = &PINF, .addr = 7 },
+            .shift_clock    = { .ddr = &DDRF, .port = &PORTF, .pin = &PINF, .addr = 6 },
+            .latch_clock    = { .ddr = &DDRF, .port = &PORTF, .pin = &PINF, .addr = 5 },
+        },
+    };
+
+    display_init(&display);
+
+
+    i2c_bus_t *bus = i2c_init(
+        (dio_t){ .ddr = &DDRB, .port = &PORTB, .pin = &PINB, .addr = 5 },
+        (dio_t){ .ddr = &DDRB, .port = &PORTB, .pin = &PINB, .addr = 6 }
+    );
+
+    i2c_error_e status = i2c_ok;
+    i2c_start(bus, &status);
+    i2c_write_byte(bus, 0x39 << 1, &status);
+    i2c_write_byte(bus, 0x80, &status);
+    i2c_write_byte(bus, 0x03, &status);
+    i2c_end(bus, &status);
+
+    if (status != i2c_ok) {
+        display_clear(&display);
+        display_write_message(&display, "early abort");
+    }
+
+    _delay_ms(500);
+
+    uint8_t count = 0;
+    while(1) {
+        /*
+        int id = 0;
+
+        status = i2c_ok;
+        i2c_start(bus, &status);
+        i2c_write_byte(bus, 0x39 << 1, &status);
+        i2c_write_byte(bus, 0x80, &status);
+        i2c_restart(bus, &status);
+        i2c_write_byte(bus, (0x39 << 1) | 1, &status);
+        id = i2c_read_byte(bus, true, &status) & 0x03;
+        i2c_end(bus, &status);
+        */
+
+        int lux = 0;
+        int ir = 0;
+        i2c_start(bus, &status);
+        i2c_write_byte(bus, 0x39 << 1, &status);
+        i2c_write_byte(bus, 0x8c, &status);
+        i2c_restart(bus, &status);
+        i2c_write_byte(bus, 0x39 << 1 | 1, &status);
+        lux = i2c_read_byte(bus, false, &status);
+        lux |= i2c_read_byte(bus, true, &status) << 8;
+        i2c_end(bus, &status);
+
+        i2c_start(bus, &status);
+        i2c_write_byte(bus, 0x39 << 1, &status);
+        i2c_write_byte(bus, 0x8e, &status);
+        i2c_restart(bus, &status);
+        i2c_write_byte(bus, 0x39 << 1 | 1, &status);
+        ir = ((int)i2c_read_byte(bus, false, &status));
+        ir |= ((int)i2c_read_byte(bus, true, &status)) << 8;
+        i2c_end(bus, &status);
+
+        char msg[20] = "";
+        display_clear(&display);
+        snprintf(msg, 20, "[%d] %x, %x", count, lux, ir);
+        display_write_message(&display, msg);
+        display_set_location(&display, 1, 0);
+        i2c_status_to_string(status, msg);
+        display_write_message(&display, msg);
+        _delay_ms(1000);
+        count++;
+    }
+}