1. ECE 477 Design Review Team 4  Fall 2012 Paste a photo of team members here, annotated with names of team members.

2. Project Overview Automated Coffee Roaster – Popcorn popper Includes heating elements and fan – Automatic roasting added User interface Optically tracks bean color Monitors heat with IR Thermometer Listens for relevant cracks with microphone

3. Project-Specific Success Criteria An ability to achieve different levels of roasting based on user input An ability to detect the temperature of the beans An ability to monitor the color of the beans An ability to interact with the user through a GUI An ability to shut off the device if unusual conditions (high temperatures, unusual color, abnormally long time) are detected

4. Block Diagram Heat Coils Relay 1 Relay 2 Power Supply Fan 7805 Voltage Rectifier Rotary Encoder LED I 2 C Bus Hacrocam Board Infrared Thermometer LCD Display Microphone LM386 Pre-Amp Reset ATmega 168 Reset PA0 PD5 PD0 PD4 PD1-3 PC0 / PC1 Vcc

5. Component Selection Rationale ATmega 168 – Atmel recommended for home appliances – 16KB self-programming flash program memory – 512-byte EEPROM – Compatible with Arduino software stack Hacrocam – Open source – Mounted microcontroller that is also compatible with Arduino software stack

6. Component Selection Rationale IR Thermometer (MLX90614KSF-ACF) – -70°C – 380°C detection range – 10 degree field of view, trig verified – Compensated temperature gradient LCD Display (NHD-C220BiZ) – Simple communication method – Transflective – Resists wide temperature range

7. Component Selection Rationale Microphone – Highly directional – Very cheap LED – White light to not bias color – Lid will be covered with high-heat spray and aluminum to isolate light

8. Component Selection Rationale AC Relays (Heating Coils) – 240 V @ 12 A (only need 10A) – Fast switching (40 ms transition) – Activation voltage of minimum 4V – Solid State DC Relay (Fan) – 30 V @ 2A – Solid State

9. Packaging Design As simple as possible, but homely External build quality of the Nesco product Operational similarity, simplicity, and homely of Engadget product More functionality than both, better component placement Minimal exterior components

10. Theory of Operation (Heat Dissipation) All components are high heat rated Camera will be behind acrylic heat shield Microphone will have metal mesh windscreen All electronics besides sensors will be below heating chamber Fans and ventilation ducts will further cool all electronics

11. Theory of Operation (Power) Wall voltage will run the heating coils directly Wall voltage will be transformed to 25.2 VAC and then rectified to run the fan. Also transformed to 12.6 VAC, rectified, and sent through a 7805 voltage regulator to power the microcontroller at 5V

12. Theory of Operation (I 2 C) Two microcontrollers The Hacrocam, IR Thermometer, and LCD screen will be accessed via I 2 C bus. Hacrocam will use self-mounted micro to average picture color before sending data. Base microcontroller will track and average the last 2-3 IR temperature readings. LCD screen will be used to communicate with the user.

13. Theory of Operation (User Interaction) Rotary encoder will allow the user to scroll through and select roasting options Reset will allow the user to cancel the roasting at any time Microphone will establish a “noise floor” to monitor base number of peaks in the area – Will listen to number of peaks for every other half second to determine if the beans are cracking

14. Schematic/Theory of Operation

15. Schematic/Theory of Operation: Power Circuit

16. Schematic/Theory of Operation: Relay Circuits

17. Schematic/Theory of Operation: LED Circuit

18. Schematic/Theory of Operation: I2C Circuit

19. Schematic/Theory of Operation: Microphone/Amplifier Circuit

20. Schematic/Theory of Operation: Reset Circuit

21. Schematic/Theory of Operation: Oscillator Circuit

22. Schematic/Theory of Operation: Microcontroller Decoupling Capacitors

24. General Consideration Acid Traps, no acute angles Signal Bounce, no right angles Signals in different layers should pass perpendicularly if possible Analog and Digital need separate grounds (star routing) Ground Fill in real PCB

25. PCB Layout: Solid State Relays Control signals need minimal amounts of current: ~30mA. Standard 10mil trace will suffice SSR1: Mounted on the PCB, will have to pass 1.7A of 20VDC for the fan. This will need to have >50mil traces and molex connectors, plus etxra space between traces SSR2: Mounted separately from PCB

27. PCB Layout: I2C 100KHz operation; noise, impedance, and signal length possible concerns (rated to ~1m) Rule of thumb: <1/10 of wavelength, transmission line effects not a concern I2C fall time is about 100ns = 5MHz Wavelength@5MHz = ~100meters We're well under 10 meters, not concerned

28. PCB Layout: Power Supply Conversion: 12.6VAC -> ~12VDC -> 5VDC As with SSR, needs to be relatively isolated 7805 will need heatsink, so some keepout area will be needed Header pins are rated at 1A each, should be sufficient for power supply

30. PCB Layout: Microcontroller All voltage pairs have decoupling caps, need to be placed nearby Want to attempt to keep uC and headers away from switching noise of amplifier and transistors Crystal and associated caps are slammed up against the microcontroller

32. Software ATMEGA – Arduino software stack Open-source, higher level Processing language Included libraries for I 2 C Hacrocam – Interfaces with Arduino Software – Programmable through serial interface – Extra SRAM for additional processing routines Color averaging done on-chip

33. Basic Software Execution

34. Project Completion Timeline Week from nowAction Item(s) 1Proof of Parts/PCB [PCB is done] 2Software Design Narrative 3Main microcontroller software 4Hacrocam controller software 5Finalize packaging, complete device assembly 6Thanksgiving 7Final testing and quality assurance 8Product presentation and submission

35. Questions / Discussion