In the NozzleMon system, a Freescale ZigBee family evaluation board, the 13192-EVB, serves as the controller in the pump panel unit (PPU) to receive and display the nozzle’s data. An MC13192 sensor application reference design (SARD) board serves as the nozzle unit (NU) processor that manages the sensors near the nozzle.
The software for this project is based on the lighting demonstration software that comes with Freescale’s SMAC package. The pump panel unit’s code simply sends out a polling message for the nozzle unit to respond and then waits for a response or a timeout. The only possible responses from the nozzle unit are either a nozzle pressure to report or a “nozzle out of control” message, which is encoded as a nozzle pressure of 255 psi (an otherwise impossible reading).
Managing the front panel switches and displays is a straightforward process, especially because the LCD assembly contains a Hitachi HD44780U controller that’s compatible with the routines included in the LCD interface in the SMAC package. More sophisticated communication and display management will be required with multiple nozzles to monitor.
Multiple nozzles can be accommodated in the same software structure by polling to see how many nozzles are enabled and adjusting the front panel to display the pressure and state of the nozzles. Polling each of the nozzles enables the pump panel unit to control the flow of the data and manage the available bandwidth as opposed to having the nozzle units broadcast continuously. This should keep enough bandwidth available for other 802.15.4 applications to be used on the fire scene.
The ZigBee platform coupled with the wide array of Freescale transducers is an effective system that will bring much-needed automation and data collection capabilities to the fire scene. Ever more sophisticated firefighting devices and equipment (from nozzles to trucks to chemical fire suppressants) are continually being put into service, but it’s difficult to integrate the new technologies with the existing apparatus and, more importantly, people.
Being able to provide real-time operating data with systems like the NozzleMon will make firefighters safer and more effective. It will also enable the efficient use of firefighting technologies.
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