Green Thermostat - Group 30

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Green Thermostat - Group 30

• Andrew Ofisher
• Brittney Campbell

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Introduction

• Goal Create an energy efficient thermostat.
• According the US Department of Energy, heating
  and cooling
• Account for about 56 of the energy use in a
  typical U.S. home
• Is the largest energy expense for most homes

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Features

• The thermostats A.I. only heats/cools home when
• Occupancy detected
• Occupancy predicted
• Manual Override engaged
• LED backlight user interface only active when
  engaged by user.

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Finished Product
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System Overview

• Hardware
• Microchip PIC 18F67J60
• Temperature Sensor
• Motion Sensor
• TS-100
• Software
• Microchip TCP/IP Stack
• Thermostat A.I.
• Web-based Interface

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System Overview
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Hardware Overview

• Control Board
• Temperature Sensor
• Motion Sensor
• User Interface

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Control Board

• PIC 18F67J60
• Ethernet interface
• Communicates with
• Buttons
• Temperature Sensor
• Motion Sensor
• Ethernet
• Non-volatile Storage

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Control Board Schematic
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Temperature Sensor

• Microchip MCP9803
• Accurate to 1 degree from 0C to 85C
• I2C Interface

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Motion Sensor

• Parallax PIR Sensor
• 20ft range
• Digital output

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Motion Sensor

• Test Results
• 25ft range
• 150 range

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User Interface

• Main Components
• Display
• TouchCells
• Graphics Layer

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User Interface Schematic
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User Interface PCB
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User Interface - Display

• 7-Segment LED Displays
• American Opto SMA-561LB G/W
• Common Anode
• In house part
• Color
• Single instead of Dual

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User Interface - Display

• Blue LED SOD-323
• TouchSensor custom part DLBLTT02Z
• In house part
• Color
• Small, brilliant
• Reverse mount
• 150 degree viewing angle

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User Interface - Display

• Blue SMD PLCC-4 LEDs
• TouchSensor custom part DLBLPR01Z
• In house part
• Color
• Very high Luminous Intensity Output
• Diffusion through reflector

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User Interface-Touchcell

• The Touchcell is a digital software free
  Field-Effect switch comprised of
• One TS-100 IC
• Electrode Structure
• Calibration Resistors

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User Interface-Graphics Layer

• A Corel Drawl Negative Image
• Image converted to a DXF and imported in to PCB
  file
• Negative image on photo transparency
• Optical adhesive
• Slightly Larger
• than PCB

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User Interface Graphics Layer
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Software Overview

• Mirochip TCP/IP stack
• Thermostat A.I.
• Web-based Interface

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Microchip TCP/IP Stack

• Fully operable TCP/IP stack written in C
• HTTP Server
• DHCP Client
• SNTP Client
• SMTP Client

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Thermostat A.I.

• Simple but effective algorithm
• Calculates probability of occupancy for 10 minute
  intervals
• Data stored in EEPROM
• Occupancy threshold and vacant temperature change
  are user defined

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Thermostat A.I.

• If
• occupancy probability below threshold
• no occupancy detected
• and override not enabled
• Target temperature is allowed to float

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Thermostat A.I.

• Example
• Cooling with target temperature of 75
• Occupancy Probability at 40
• No occupancy Detected, No override
• Occupancy Threshold 50, Vacant Temperature
  Change 5
• Temperature allowed to rise to 80

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Web-based Interface

• Allows for control of thermostat configuration
• Occupancy Threshold
• Vacant Temperature Change
• Full control of thermostat schedule
• 7 day, 10 minute interval schedule
• Separate temperatures for heat and cool

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Web-based Interface
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Web-based Interface
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Touch Cell Problems

• As finger approaches cell, digital output
  oscillates

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Touch Cell Problem

• Solution
• Instead of using interrupts, poll at set
  frequency
• Two reads of high is considered a touch
• Poll at 39.736hz or 25ms
• 41,666,667/(1665536)

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Product Validation

• Ramped product from 0 to 90 relative humidity,
  power off
• Temperature sweep from -20C (-4F) to 50C
  (122F), power on
• Failure of Proxy Touchcell at 50C

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Thermostat A.I. Validation
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Future Development

• Implement Damper Control
• Utilize multiple motion and temperature sensors
• Variable room target temperatures
• Phone based remote control
• Better preemptive temperature control

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Thank You

• Any questions?