The code was implemented and installed on 4 motes such that the mote with TOS_NODE_ID = 4 acted as a light sensor(photo resistor). The 4th sensor sampled the light intensity data and broadcasts it. Mote 3 detects the packets coming from mote 4 and broadcasts them. In the same way, mote 2 will only accept packets coming from mote 3 and it will broadcast them. Mote 1 checks if the packets are coming from mote 2 and it will check again if the light intensity value received from mote 2 is less than the threshold value. If it is greater than the threshold, mote 1 will sound the buzzer.