 
     Timer1.initialize(US_PER_TICK);
     Timer1.attachInterrupt(tick);
+    
+    for(i = 0; i < NUM_CLASSES; i++)
+        g_classes[i] = NO_CLASS;
 }
 
 void loop()

                    g_classes[i] = NO_CLASS;

                for(i = 0; i < len - 2; i++)
                    g_classes[i] = data[i];

                break;
            }
        case PACKET_CALIBRATE:

    uint8_t   *data;

    target = packet[0];
    if (target >= MAX_NODES + 1)
    {
        uint8_t cls = target - (MAX_NODES + 1), i;

        //Serial.println("packet to class: " + String(cls));
        for(i = 0; i < NUM_CLASSES; i++)
            if (g_classes[i] == cls)
            {
                //Serial.println("I am class " + String(cls));
                target = g_node_id;
                break;
            }
