messages and all radio settings can be changed in situ enabling the radios to change to whom they are communicating as necessary as they execute the individual tasks. In transparent mode, no additional information is provided to the units about the origin of the messages they receive. To remedy this issue, a packet structure is designed for this project. Packets typically include a byte indicating the length of the message; however, in this case the length information is unnecessary because each possible message is a command or sensor reading of the same length with one exception, the transmission of the utility curves from zone manager to building server. For the curve transmission case, the zone manager sends a will be sent” command followed “curve by a message containing the length of the data stream that is queued up for the next transmission. Upon receiving this specific message, the building server enters a state responsible for handling the subsequent data stream. In place of a message integrity check, the function that reads in the packet information verifies the packet header, the to” byte, the from” byte, and that message itself is an appropriate message “unit “unit for the current state and the units involved. If any of these conditions are not met, the message is discarded. To avoid missing important messages, the units receiving messages send acknowledgement commands to the units from whom they receive messages. The sending unit continues to issue the command until it receives an acknowledgement confirmation. Figure 3-7 depicts the packet structure used for wireless communication throughout the tiered system. Figure : RF Packet Structure. A/D Module and Sensor Signal Interpretation The Atmega64 built in Analog to Digital (A/D) converter is used for taking sensor measurements. This microcontroller has an 8-channel multiplexed analog input. The A/D module first waits to ensure no other lines on the multiplex are in use and then
messages and all radio settings can be changed in situ enabling the radios to change to whom they are communicating as necessary as they execute the individual tasks. In transparent mode, no additional information is provided to the units about the origin of the messages they receive. To remedy this issue, a packet structure is designed for this project. Packets typically include a byte indicating the length of the message; however, in this case the length information is unnecessary because each possible message is a command or sensor reading of the same length with one exception, the transmission of the utility curves from zone manager to building server. For the curve transmission case, the zone manager sends a “curve will be sent” command followed by a message containing the length of the data stream that is queued up for the next transmission. Upon receiving this specific message, the building server enters a state responsible for handling the subsequent data stream. In place of a message integrity check, the function that reads in the packet information verifies the packet header, the “unit to” byte, the “unit from” byte, and that message itself is an appropriate message for the current state and the units involved. If any of these conditions are not met, the message is discarded. To avoid missing important messages, the units receiving messages send acknowledgement commands to the units from whom they receive messages. The sending unit continues to issue the command until it receives an acknowledgement confirmation. Figure 3-7 depicts the packet structure used for wireless communication throughout the tiered system. Figure : RF Packet Structure. A/D Module and Sensor Signal Interpretation The Atmega64 built in Analog to Digital (A/D) converter is used for taking sensor measurements. This microcontroller has an 8-channel multiplexed analog input. The A/D module first waits to ensure no other lines on the multiplex are in use and then
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