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The Wireless Probe

How it works

The wireless system utilized the Roaming Networks RN-42 Class 2 Bluetooth module. This module required a minor configuration change for the master module; otherwise it was utilized entirely in its factory configuration. In this configuration, the module connects to the microcontroller via UART and is completely transparent to the microcontroller. Whatever is placed on the UART transmit buffer is sent out to the microcontroller, into the RN-42, and over the air to the other RN-42. Whatever data the RN-42 receives is placed on the microprocessor's UART receive buffer. The microprocessor's coding will then interprets the data in the buffer and determines if a fire has been detected and change status accordingly. In order to effectively detect a fire, the remote wireless probe can be placed in a separate room from the rover given that the rover can still read a prepared line to the room. The remote probe will constantly be monitoring for a fire through the use of the Hamamatsu UVTron, the Roving Network RN-42, a MSP430-G2553, and a standard 9V battery. Because the entire probe runs on ultra low power, the battery is able to support all these components without fear of being drained quickly.

After power on and initialization, the remote probe rests in a very low power standby mode. When a pulse is received from the UVTron, the processor wakes up and checks for more pulses to determine if a legitimate fire is present rather than the UVTron picking up a stray UV source. If the fire is determined to be legitimate, the local RN-42 is instructed to establish a connection to the remote RN-42. The remote probe then transmits the byte “0x0F’. Every 30 seconds, the probe re-evaluates the data from the UVTron to determine if a fire is still present. Once the UVTron stops alarming, the RN-42 transmits the byte “0x00” and then disconnects from the remote RN-42. Upon disconnect, the processor goes back into very low power mode, necessary again because of the high voltage low capacity battery used in the remote probe.