diff --git a/Joystick.cpp b/Joystick.cpp
index e53b715..c518999 100644
--- a/Joystick.cpp
+++ b/Joystick.cpp
@@ -3,11 +3,8 @@
 
 Joystick::Joystick(bool debug) {
   _debug = debug;
-}
-
-void Joystick::Init() {
-  Serial.begin(115200);
-  delay(100);
+  _num_buttons = 0;
+  _num_axes = 0;
 
   for (uint8_t i=0; i < JOYSTICK_NUM_AXES; i++) {
     _joyReport.axis[i] = 0;
@@ -15,20 +12,44 @@ void Joystick::Init() {
   for (uint8_t i=0; i < JOYSTICK_NUM_BYTES; i++) {
     _joyReport.button[i] = 0;
   }
-  
+}
+
+void Joystick::Init() {
+  Serial.begin(115200);
+  delay(100);
+
   if (_debug) Serial.println("DEBUG: Joystick library initialized.");
 }
 
 void Joystick::AddButton(uint8_t pin, ButtonType type) {
-  // stub
+  _buttons[_num_buttons].pin = pin;
+  _buttons[_num_buttons].type = type;
+  _buttons[_num_buttons].last_state = digitalRead(pin);
+  _num_buttons++;
 }
 
 void Joystick::AddAxis(uint8_t pin) {
-  // stub
+  _axes[_num_axes] = pin;
+  _num_axes++;
 }
 
 void Joystick::Update() {
-  // stub
+  JoyReport oldReport = _joyReport;
+  
+  for (int i = 0; i < _num_buttons; i++) {
+    uint8_t value = digitalRead(_buttons[i].pin);
+    // TODO: handle button according to ButtonType
+  }
+
+  for (int i = 0; i < _num_axes; i++) {
+    uint16_t value = analogRead(_axes[i]);
+    // TODO: convert raw analog value to something sensible for
+    //   HID Analog data.
+  }
+
+  if (_joyReport != oldReport) {
+    Serial.write(_joyReport);
+  }
 }
 
 void Joystick::SetAxis(uint8_t axis, int16_t value) {
diff --git a/Joystick.h b/Joystick.h
index 85d1c9b..7f7ab07 100644
--- a/Joystick.h
+++ b/Joystick.h
@@ -44,9 +44,15 @@ class Joystick {
 
   private:
     struct {
-      
+      uint8_t pin;
+      ButtonType type;
+      uint8_t last_state;
     } _buttons[JOYSTICK_NUM_BUTTONS];
     uint8_t _num_buttons;
+
+    uint8_t _axes[JOYSTICK_NUM_AXES];
+    uint8_t _num_axes;
+    
     JoyReport _joyReport;
     bool _debug;
 };