1. ECE 477 Design Review Group 1  Spring 2005

2. Outline Project overviewProject overview Project-specific success criteriaProject-specific success criteria Block diagramBlock diagram Component selection rationaleComponent selection rationale Packaging designPackaging design Schematic and theory of operationSchematic and theory of operation Preliminary PCB layoutPreliminary PCB layout Software design/development statusSoftware design/development status Project completion timelineProject completion timeline Questions / discussionQuestions / discussion

3. Project Overview Receive input from three types of sensors: a universal flame detector, directional temperature sensors, and directional distance sensorsReceive input from three types of sensors: a universal flame detector, directional temperature sensors, and directional distance sensors Inputs processed by microcontrollerInputs processed by microcontroller Microcontroller drives maneuvering motors and servos to trigger the fire extinguisherMicrocontroller drives maneuvering motors and servos to trigger the fire extinguisher Sounds a siren in the presence of a fireSounds a siren in the presence of a fire Software to operate in three modes: off, “one eye open” and patrolSoftware to operate in three modes: off, “one eye open” and patrol

4. Project-Specific Success Criteria Ability for the software to maneuver the robot on an arbitrary indoor surface, avoiding walls or other objects while maneuvering. Ability to detect a nearby fire with minimal false positives (from non-flame heat sources) and determine the fire’s position relative to the robot. Ability to maneuver the robot into position to extinguish a fire based on data from the sensors. Ability to activate a fire extinguisher to extinguish a fire when the robot is already in the correct position. Ability to display state information to a user through an LCD interface

5. FIREBot Block Diagram Power Supply Universal Flame Detector Wide Angle Flame Detectors Narrow Angle Flame Detectors Distance Sensors Push Buttons Siren Sensor Platform Servo Microcontroller Motor Drivers LCD Output Debug Port Extinguisher Trigger Servo

6. Component Selection Rationale Microcontroller The microcontroller must have sufficient peripherals to interface to all of the external components as well as sufficient FLASH and SRAM to store all the code and the data in operation. It must be inexpensive, easily available, and easy to prototype The Atmel ATMega32 – – 4 PWMs, 8 Analog-To-Digital Converters, one UART – –32k FLASH, 2K SRAM, 1K EEPROM – –Easily available in a PDIP Package The Motorola MC9S08GT32CFB – –4 PWMs, 8 Analog-To-Digital Converters, one UART, one IR UART – –32K FLASH and 2K SRAM. – –Also available in a DIP package. We have tentatively chosen the Atmel ATMega32 because of low cost and good development package. The Motorola MC9S08GT32CFB-ND is a workable alternative.

7. Component Selection Rationale Wide Angle Flame Detector Wide Angle Flame Detectors find flames at a long distance and at a (relatively) wide-angle, and provide angular position location to the flame Hamamatsu UVTron – UV Detector which is very sensitive but with strong discrimination. Detects a candle at 5m. – –Unacceptable: Updates every 3s UV Photodiode: Less sensative and less discrimination, but analog – –Very low output current – –Unacceptable: Didn’t detect flames in experiments, but reacted to flourescent lights IR Photodiode: Much less discrimination, also analog – –Reacts some to flourescent lights, but more to flames IR photodiode chosen to be better option since no way to get around problem of a UV photodiode under florescent lighting

8. Packaging Design Packaging carefully designed to protect delicate parts without sacrificing operation Due to large amounts of heat, need a heat shield to protect the micro and some sensors Structure intended to be simple, easily accessible and easily modified Electronic components need to be protected from the chemical released by fire extinguisher to put out fire Robot powered by an onboard rechargeable battery Onboard 4 lb fire extinguisher used to extinguish fires

9. Schematic/Theory of Operation The FIREbot Electrical Schematics are built in a hierarchical structure, with blocks performing the following functions: Power Supply Universal Flame Detector Wide Angle Flame Detector Narrow Angle Flame Detector Distance Sensors Push Buttons Microcontroller Motor Drivers Sensor Platform Driver Extinguisher Trigger Siren LCD Outputs Debug Port

10. Power Supply Unit The power supply block outputs 4 voltage rails A 5V rail for digital components (Switching Regulator) A 5V rail for analog sensors (Linear Regulator) A 5V rail for servos (Switching Regulator) A 12V rail for analog components Three separate 5V rails isolate the noise caused by each type of component p-channel power MOSFETs used so microcontroller can turn off all but Digital rail Sheet 15

11. Power Supply Unit Top Level

12. Switching Power Supply

13. Linear Regulator

14. Universal Flame Detector Major component is the UVTron UVTron sensor connected to small PCB that asserts a pulse when it detects a flame Open collector output of UVTron’s circuit board used to clock a D-flip flop Output of D-flip flop serves as an interrupt to the microcontroller Microcontroller can clear the interrupt flag with a clear signal 5V digital rail used to supply all components in block, including UVTron’s circuit board Sheet 21

15. Universal Flame Detector

16. Wide Angle Flame Detector Provides interface to IR photodiodes that detect flames in a wide field of vision at long distance Block physically separate from main PCB, sits on turntable controlled by a servo to detect flames and provide angular position Special circuit developed with current input inverting op-amp along with band pass filter to amplify signal to a large voltage and filter off noise Output current from IR photodiodes amplified into voltage that can be read by a microcontroller A-to-D pin Sheet 22

17. Wide Angle Flame Detectors

18. Narrow Angle Flame Detector Raytec Compact CI active infrared temperature sensor and requiring 12V to operate Simple interface block Analog output connected to an A-to-D converter on the microcontroller Output voltage proportional to surface temperature of object in field of view Sheet 14

19. Narrow Angle Flame Detector

20. Proximity Sensors Sharp GP2D120 active infrared proximity sensor interface consists of four identical circuits Individual circuits incorporate a single active infrared distance sensor Outputs from each distance sensor connected to a separate A-to-D port on the microcontroller Analog supply rail of 5 volts used to power circuits to isolate analog sensors from switching noise of digital components Sheet 7

21. Proximity Sensors

22. Microcontroller ATMega32 microcontroller 8-bit serial shift register connected to microcontroller pin increases number of logic signals Active low reset pin on micro connected to standard SPDT pushbutton switch circuit Capacitors used across power and ground pins for both digital and analog circuits 8 MHz oscillator connected to the two oscillator pins of microcontroller AVRISP interface necessary to program microcontroller Sheet 12

23. Microcontroller

24. Servo Motor Drivers Extinguisher Trigger and Sensor Platform Drive blocks identical, controlling similar servos Optical isolation for PWM signals Decoupling capacitors for power Dedicated 5V rail for servos to prevent noise on other power lines Sheets 8 and 19

25. Servo Driver Circuit

26. DC Motor Drivers Block responds to signals from microcontroller to drive the two power motors of FIREBot PWM used to control speed of each motor Inputs are 8 digital signals from micro 4 for each motor Signals are Forward, Reverse, Brake, and PWM Outputs are analog drive voltages connecting directly to positive and negative terminals of the power motors 3 parts: glue logic, H-bridges, snubbers Sheets 13 and 10

27. DC Motor Driver Circuit Top Level

28. Half of an H-Bridge

29. Siren Interface Interfaces a 12V siren to a pin of the micro Input is Siren_Activate signal from the micro Output is positive and negative terminals of siren Optically isolated Siren_Activate signal controls gate of FET to switch positive terminal of siren. Activated LED is alternative to siren if necessary Sheet 20

30. Siren

31. Serial Debug Port Interface Provides an RS-232 interface through which external PC can connect to FIREBot Can also be used to send simple commands TX and RX are 5V digital signals connected directly to micro TX and RX signals optically isolated from analog circuitry TX and RX signals level-shifted to +/-12V logic levels on RS-232 Outputs to pins of DB9 serial connector Sheet 6

32. Serial Debug Interface

33. Push Buttons 3-way switch provides the only user input to the robot Center position indicates off mode Left and right positions select one of two operating modes Capacitors effectively de-bounce the switch Sheet 16

34. Character LCD Interface 20x4 Character LCD for status feedback20x4 Character LCD for status feedback LCD interface based on 74HC74 8-bit serial shift register Shift register input driven by port pin on micro Shift register reduces number of port pins required send data LCD from eight to one Other LCD control signals (i.e. LCD_STROBE) driven directly by port pins on micro Potentiometer to control contrast of LCD Sheet 9

35. Character LCD Interface

36. Preliminary PCB Layout

37. Digital Switching Power Supply

38. Preliminary PCB Layout Digital Switching Power Supply 12V Switch

39. Preliminary PCB Layout Digital Switching Power Supply Servo Switching Power Supply 12V Switch

40. Preliminary PCB Layout Digital Switching Power Supply Servo Switching Power Supply Analog Flame & Proximity Sensors ` 12V Switch

41. Preliminary PCB Layout Digital Switching Power Supply Servo Switching Power Supply Analog Flame & Proximity Sensors ` 12V Switch 5V Linear Regulator

42. Preliminary PCB Layout Digital Switching Power Supply Servo Switching Power Supply Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator

43. Preliminary PCB Layout Digital Switching Power Supply Servo Switching Power Supply Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator LCD Display

44. Preliminary PCB Layout ATMega32 Digital Switching Power Supply Servo Switching Power Supply Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator LCD Display

45. Preliminary PCB Layout ATMega32 Digital Switching Power Supply Servo Switching Power Supply Serial Debug Port Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator LCD Display

46. Preliminary PCB Layout ATMega32 Digital Switching Power Supply Servo Switching Power Supply Serial Debug Port Siren Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator LCD Display

47. Preliminary PCB Layout ATMega32 Digital Switching Power Supply Servo Switching Power Supply Serial Debug Port Siren Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator DC Motor H-Bridges LCD Display

48. Preliminary PCB Layout ATMega32 Digital Switching Power Supply Servo Switching Power Supply Serial Debug Port Siren Analog Flame & Proximity Sensors ` Servo Motor Drivers 12V Switch 5V Linear Regulator DC Motor H-Bridges LCD Display Turntable Mounted PCB

49. Software Design/Development Status

51. Project Completion Timeline Week of March 7Week of March 7 –Complete PCB layout –Learn AVR development environment. Week of March 21Week of March 21 –Populate PCB –Install all sensors and parts on structure –Begin writing hardware control state machines Week of March 28Week of March 28 –Complete Writing and Verify hardware control state machines Week of April 4Week of April 4 –Write and verify One-Eye-Open and Extinguish software State Machines Week of April 11Week of April 11 –Write and verify Patrol Mode software state machine Week of April 18Week of April 18 –Write and verify Approach Mode software state machine Week of April 25Week of April 25 –Verify system functionality Week of May 2Week of May 2 –Demonstrate system functionality –Write Final documentation

52. Questions / Discussion