ece 477 design review team 4 fall 2012
Download
Skip this Video
Download Presentation
ECE 477 Design Review Team 4  Fall 2012

Loading in 2 Seconds...

play fullscreen
1 / 35

ECE 477 Design Review Team 4  Fall 2012 - PowerPoint PPT Presentation


  • 123 Views
  • Uploaded on

ECE 477 Design Review Team 4  Fall 2012. Paste a photo of team members here, annotated with names of team members . Project Overview. Automated Coffee Roaster Popcorn popper Includes heating elements and fan Automatic roasting added User interface Optically tracks bean color

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' ECE 477 Design Review Team 4  Fall 2012' - hastin


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
ece 477 design review team 4 fall 2012

ECE 477 Design Review Team 4  Fall 2012

Paste a photo of team members here, annotated with names of team members.

project overview
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
project specific success criteria
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
block diagram

Heat Coils

Power Supply

Fan

Relay 1

Relay 2

7805 Voltage Rectifier

Vcc

PD5

PD4

ATmega 168

LM386

Pre-Amp

Rotary Encoder

PA0

PD1-3

Microphone

Reset

PC0 / PC1

Reset

PD0

LED

I2C Bus

Hacrocam Board

Infrared Thermometer

LCD Display

Block Diagram
component selection rationale
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
component selection rationale1
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
component selection rationale2
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
component selection rationale3
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
packaging design
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
theory of operation heat dissipation
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
theory of operation power
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
theory of operation i 2 c
Theory of Operation (I2C)
  • Two microcontrollers
  • The Hacrocam, IR Thermometer, and LCD screen will be accessed via I2C 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.
theory of operation user interaction
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
slide23

Power

Mic

Analog

IO

uC and

Digital IO

general consideration
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
pcb layout solid state relays
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
pcb layout i2c
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
  • [email protected] = ~100meters
  • We\'re well under 10 meters, not concerned
pcb layout power supply
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

pcb layout microcontroller
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
software
Software
  • ATMEGA
    • Arduino software stack
      • Open-source, higher level Processing language
      • Included libraries for I2C
  • Hacrocam
    • Interfaces with Arduino Software
    • Programmable through serial interface
    • Extra SRAM for additional processing routines
      • Color averaging done on-chip
ad