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Remote Fire Alarm

Remote Fire Alarm. Nick Rymer Brian Robinson Adam Lehotay Josh Bertovich. Introduction. Problem Location with Multiple Buildings Unmanned Buildings Buildings hundreds of feet apart. Introduction. Existing Systems Stand Alone Alarms Someone Must Hear Alarm Hardwired

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Remote Fire Alarm

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  1. Remote Fire Alarm Nick Rymer Brian Robinson Adam Lehotay Josh Bertovich

  2. Introduction • Problem • Location with Multiple Buildings • Unmanned Buildings • Buildings hundreds of feet apart

  3. Introduction • Existing Systems • Stand Alone Alarms • Someone Must Hear Alarm • Hardwired • Complex and Expensive • Inflexible

  4. Solution • Wireless System • Easy Installation • Can Monitor Many Buildings • 1 unit can Monitor Entire System

  5. Principle of Operation • 1 Central Unit • Displays Information About Entire System • Up to 8 Remote Fire Alarms • Transmit Status to Central Unit

  6. Central Unit

  7. Remote Unit

  8. Remote System • Remote Alarm Status • Normal Operation • Fire • Low Battery • Communication Loss • Adding Devices • Removing Devices

  9. Performance Specification • User-friendly installation, setup, and operation

  10. Performance Specification • Central and Remote Units will be powered by 120 VAC • Battery backup in the Remote Units • Maximum of eight remote units controlled by one central unit • The status of all remote units will be known by the central unit in less than one second • Remote Units will detect smoke with ionization chambers

  11. Performance Specification • Maximum communication distance between central unit and remote unit will be 500 feet with obstructions

  12. Standard Electrical Outlet Remote Alarm Unit 6Volt Battery 120 VAC 6V DC AC-DC adapter 5 Volt Power Regulator 5 Volts Regulated Internal Switch +5V Test Switch Ionization Chamber IC Smoke Detector chip Ion chamber status Speaker Siren Signal, To sound alarm Ion chamber status Central Unit Signal to Central Unit Decoded Signal from Central unit RF Output RF Input Transceiver PIC Control Unit User Switch System Design • Block Diagram of Remote Unit +5V

  13. Remote Unit PIC Operation • Infinite loop which checks the status of I/O pins on the PIC • Devices being checked on I/O pins • Transceiver • IC Smoke Detector Chip (Ionization chamber and battery level monitoring) • Learn Button • Abnormal events on a device cause a sub-function to be called

  14. Fire Alert Function • Invoked when a local fire is detected • The local alarm is sounded and the Central Unit is notified of event

  15. Remote Fire Function • Executed when there is a fire at another location • Transceiver receives signal from Central Unit to sound alarm

  16. Low Battery Alert Function • Executed when battery power drops near minimum operational levels • Receives alert from IC Smoke Detector Chip and transceiver sends alert to central unit

  17. Learn Function • Executed when the user presses the learn button on the local unit • Transceiver sends signal to Central Unit • Central Unit sends signal containing the network address that the unit will respond to when polled

  18. Standard Electrical Outlet Central Unit 120 VAC AC-DC adapter 5 Volt Power Regulator 6V DC 5 Volts Regulated +5V 8 User Switches User Input Remove Button Encoder LCD Learn Button Encoded Input Display Information Signal to Remote Unit Decoded Signal from Remote unit RF Output RF Input Remote Unit Transceiver PIC Control Unit Analog Output Speaker 8 LED Lights Central Unit Block Diagram • Shows connectivity of central unit’s components

  19. AC-DC Adaptor • Converts AC output from a standard 60 Hz 120 VAC electrical outlet into 6 Volts DC • The output of this block is the input to the 5 volt regulator block

  20. Power Regulator • Regulates the voltage so chips will function normally as well as be protected from over voltage • Regulator holds the voltage at 5 volts ±5% • Remote unit’s regulator will do the same as the central unit’s regulator except that it will regulate power for fewer devices

  21. Internal Switch • Internal switch has inputs from the battery and AC-DC adapter • Switch connects either the battery or the AC-DC adapter to the regulator • Battery will only be connected to the regulator when the AC-DC adapter is no longer providing a 6 VDC input to the switch

  22. Transceiver • FM modulation at 900 MHz • 8-bit data packets represent either a remote unit address, central unit address, or a certain function to be executed • RS-232 protocol used to transferred data between transceiver and microcontroller

  23. Transceiver • RF data received by transceiver • Data-out buffer • Request-to-send • Data from microcontroller • Data-in buffer • Clear-to-send

  24. Modes of Operation • Sleep mode • Low power consumption • Transmit mode • Transceiver takes the data from the data-in buffer and broadcasts it to the other transceiver • Receive mode • Transceiver receives data from the other transceivers and stores it in the data-out buffer • Transition mode • Transition time between modes

  25. Modes of Operation

  26. Utilizing Modes of Operation • Modes of operation should be used efficiently to save power • Transceivers in sleep mode 99% of the time • Central unit transceiver polls the next remote transceiver every second

  27. Central Unit PIC Operation Purpose: • Manages communication with remote devices • Maintains identification for each remote device • Processes and responds to user input • Controls the display

  28. Central Unit PIC I/O • Infinite loop which checks the status of I/O pins on the PIC • Devices sending information to input pins • Transceiver • Learn/Remove Buttons • Alarm Specific Buttons • Devices receiving information from output pins • Transceiver • LCD display • Alarm LEDs and speaker

  29. Fire Alert Process • Performed when fire detection is received from transceiver • Sends signal to trigger all remote devices • Displays fire detection message and alarm of concern on the display

  30. Low Battery Process • Performed when low battery is received from transceiver • Displays low battery message and alarm of concern on the display

  31. New Device Process • Performed when user presses the learn button • Halts normal operation • Selects and transmits identification for new device • Waits for new device to confirm its identity • Normal operation is restored

  32. Remove Device Process • Performed when user pushes the remove button and selects an alarm • Requires user confirmation and then the selected alarm identification is cleared

  33. Comm. Loss Process • Performed when a remote device does not respond to a status prompt • Displays communication loss message and alarm of concern on the display

  34. Performance Analysis • Typical Power used by Central Unit • Power = ITyp * 5V, 165mA * 5V .825 Watts • Maximum Power used by Central Unit • Power = ITyp* 5V, 720mA * 5V 3.6 Watts • Maximum Power Supplied AC-DC adapter • Power = IMAX * 6V, 1A * 6V 6 Watts • Maximum Power Supplied by Regulator • Power = IMAX * 5V, 1A * 5V 5 Watts • Excess Capacity • AC-DC adapter Supplies 2.4 Watts of Extra Power • Regulator loses 1 Watt of Power in Heat • Regulator Provides 1.4 Watts of extra Power to Central Unit Central Unit Power Consumption

  35. Performance Analysis • Typical Power used by Remote Unit • Power = ITyp * 5V, 15mA * 5V .075 Watts • Maximum Power used by Remote Unit • Power = ITyp* 5V, 590mA * 5V 2.95 Watts • Maximum Power Supplied by rectifier • Power = IMAX * 6V, 1A * 6V 6 Watts • Maximum Power Supplied by Regulator • Power = IMAX * 5V, 1A * 5V 5 Watts • Excess Capacity • Ac-Dc adapter Supplies 3.05 Watts of Extra Power • Regulator loses 1 Watt of Power in Heat • Regulator Provides 2.05 Watts of extra Power to Remote Unit • Battery Life Calculations • Standard 4 AA Battery Life = 6V @ 1300 Milliamp Hours • Central Unit Battery Life @ Typical Current • I = 1300 / 15 = 86.67 Hours Remote Unit Power Consumption

  36. Performance Analysis • Transceiver Performance • Transmit power output of 140 mW • Receiver sensitivity of -114 dBm • Transmission range can reach up to 1500 feet • The serial data throughput is approximately 1100 bps • Excess capacity • 1000 feet extended range beyond required range • only a fraction of the data throughput will be needed

  37. Performance Analysis • PIC Performance (Central and Remote Units) • 256k of program memory • PIC will be set to run at 2MHz • Excess capacity • Small amounts of memory will be required relative to the available 256k • At 2MHz will be processing data at a much faster rate than would be required to meet time constraints of the system

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