diff --git a/src/controller/controller.ino b/src/controller/controller.ino
index 616dd25..b2d50a1 100644
--- a/src/controller/controller.ino
+++ b/src/controller/controller.ino
@@ -13,6 +13,9 @@
 
 #define OBUS_MSG_LENGTH 8  // Max 8 to fit in a CAN message
 
+#define OBUS_MAX_MODULES 16
+#define OBUS_DISC_DURATION 1 // Duration of discovery round in seconds
+
 #define OBUS_MSGTYPE_C_ACK       0
 #define OBUS_MSGTYPE_C_HELLO     1
 #define OBUS_MSGTYPE_C_GAMESTART 2
@@ -31,12 +34,19 @@
 MCP2515 mcp2515(10);
 
 uint8_t state = STATE_INACTIVE;
+uint8_t connected_modules_ids[OBUS_MAX_MODULES];
+uint8_t nr_connected_modules;
+
+unsigned long hello_round_start;
 
 void setup() {
 	Serial.begin(9600);
 	mcp2515.reset();
 	mcp2515.setBitrate(CAN_50KBPS);
 	mcp2515.setNormalMode();
+
+  nr_connected_modules = 0;
+  
 	Serial.println("begin");
 }
 
@@ -53,29 +63,57 @@ uint16_t make_id(uint8_t id, bool priority, uint8_t type) {
 		(uint16_t) id;
 }
 
-void start_hello() {
-	state = STATE_HELLO;
-
+void send_message(unsigned char* message) {
   struct can_frame send_frame;
   
-	send_frame.can_id = make_id(OBUS_CONTROLLER_ID, false, OBUS_TYPE_CONTROLLER);
-	send_frame.can_dlc = OBUS_MSG_LENGTH;
+  send_frame.can_id = make_id(OBUS_CONTROLLER_ID, false, OBUS_TYPE_CONTROLLER);
+  send_frame.can_dlc = OBUS_MSG_LENGTH;
 
-  send_frame.data[0] = OBUS_MSGTYPE_C_HELLO;
+  memcpy(send_frame.data, message, OBUS_MSG_LENGTH);
  
-	mcp2515.sendMessage(&send_frame);
+  mcp2515.sendMessage(&send_frame);
+}
+
+void start_hello() {
+	state = STATE_HELLO;
+  hello_round_start = millis();
+
+  unsigned char message[OBUS_MSG_LENGTH];
+  message[0] = OBUS_MSGTYPE_C_HELLO;
+
+  send_message(message);
+  
 	Serial.println("sent");
 }
 
+void send_ack() {
+  unsigned char message[OBUS_MSG_LENGTH];
+  message[0] = OBUS_MSGTYPE_C_ACK;
+
+  send_message(message);
+
+  Serial.println("Send ACK");
+}
+
 void receive_hello() {
   struct can_frame receive_frame;
+  unsigned long current_time = millis();
+  
   if (mcp2515.readMessage(&receive_frame) == MCP2515::ERROR_OK) {
     Serial.println("Received message");
     if (receive_frame.data[0] ==  OBUS_MSGTYPE_M_HELLO) {
-      Serial.println("Hello"); 
+      uint8_t module_id = receive_frame.can_id;
+      Serial.print("Hello from module ");
+      Serial.println(module_id);
+      connected_modules_ids[nr_connected_modules] = module_id;
+      nr_connected_modules++;
+      send_ack();
     } else {
       Serial.println("Not implemented");
     }
+  } else if (current_time - hello_round_start > OBUS_DISC_DURATION * 1000) {
+    state = STATE_GAME;
+    Serial.println("Initializing game");
   }
 }
 
@@ -83,7 +121,7 @@ void loop() {
   if (state == STATE_INACTIVE) {
     start_hello();  
   } else if (state == STATE_HELLO) {
-      receive_hello();
+    receive_hello();
   } else if (state == STATE_GAME) {
     // Game loop  
   }