1 / 37

Integrated Electronic Window

Integrated Electronic Window. Stephen Stec Tom Ludwick Steven Silverman Betrework Tizazu Dr. Natarajan Narasimhamurthi Advisor John Finch , Masco Advisor. Project Purpose. Home Automation ‘Neat’ Factor Assist the aging population Energy Reduction Save on Heating and Cooling.

meira
Download Presentation

Integrated Electronic Window

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Integrated Electronic Window Stephen Stec Tom Ludwick Steven Silverman Betrework Tizazu Dr. NatarajanNarasimhamurthi Advisor John Finch, Masco Advisor

  2. Project Purpose • Home Automation • ‘Neat’ Factor • Assist the aging population • Energy Reduction • Save on Heating and Cooling

  3. Window Functionality • Provide an integrated solution for different electronic components that could be added to a home window • temperature sensor • H2O sensor (rain sensing) • motor drive (to open and close) • controlled light transmission/privacy • an intuitive user interface to control each solution • Certain systems of this window would work together to provide automated control as well.

  4. Tint Technology Driving Electrochromic Windows

  5. Electrochromic Windows • Chemical reaction initiated by an electric charge • Oxidation Reaction • Window Layers • Ion Storage Layer (green) • Ion Conductor Layer (yellow) • Electrochromic Layer (gray) • Reverse the polarity of the charge, reverse the direction of the reaction • This causes the window to become transparent or opaque • Reaction is very slow (~3 minutes light to dark)

  6. Electrochromic Windows • Benefits • Low Voltage (3.3V) • Uses little or no power when reaction is complete • ~10mA @ 3.3V = 33mW • Current sense resistor to indicate when reaction has completed • Drive System • Zetex ZXMHN6A07T8 N-Channel H-Bridge • Microcontroller to control switching • Light sensors to help with tint level control

  7. Light Sensors • Choice • Tested both LX1972 Ambient Light Detector and Photoresistor • Chose LX1972 because of low IR sensitivity, very repeatable output current, and an easily scalable output.

  8. Light Sensors • Testing: • Voltage divider configuration • 10 K resistor used to scale • Prototypes • Soldered onto SURF Boards and measured in parallel with light meter

  9. Light Sensors • Closed loop system: • Outer sensor is sampled by ADC and stored at the PIC • Inner light sensor is sampled by ADC and stored • The difference between the two sensors is the present level of tint • This tint level is read by the tint controller and the output is adjusted accordingly

  10. Temperature Sensors • Determines tint level in conjunction with light sensors • Placed on the inside as well as outside to measure difference (ΔT) • Cold and sunny outside-make opaque to let in warming sunlight • Hot and sunny outside-tint to keep warming sunlight out • ΔT will determine a set level of tinting

  11. Temperature Sensing • Resistance Temperature Device (RTD) • Most stable • Most accurate • Linear relationship • Vishay Platinum SMD Chip Temperature Sensor • R0 = 500 Ω at 0˚C • Automotive, Aviation, and Industrial applications • Temperature Range: -67˚F to 311˚F (-55˚ C to 155˚C) • Only need ~ -40˚F to 150˚F (-40˚ to 66˚C) • ΔR for this range is ~250Ω (400Ω to 650Ω)

  12. Temperature Sensor Design • Current Source to minimize error • Current-Sourcing Current Mirror • Choose Rbiaswith a low Temperature Coefficient • RTD measurements made with low source currents • 100μA to 250μA • Rbias≈ 20kΩ to 50kΩ

  13. Temperature Sensor Calculations • ϑ = Temperature in ˚C • Ro = Resistance at 0˚C • Rϑ = Resistance at Temperature • A and B – Part specific coefficients

  14. Window Automation Motorized Drive System

  15. Motor Functions

  16. Motor Controller Selection • N-channel MOSFET H-bridge • N-channel MOSFET and P-channel MOSFET H-Bridge • Zetex ZXMHN6A07T8 • SN754410 • Decided on L298 because it can handle the 24V and 400ma load with ease

  17. Motorized Operation Here’s how it’s laid out:

  18. Water Sensing • Detect H20 and send signal to microcontroller • Consists of interweaving copper tracks on a PCB board • Uses rain droplets to complete circuit • Send “rain” or “no rain” respectively

  19. Block Diagram

  20. Water Sensing Test • Performance Testing • 1/8” spacing between tracks • 1/12” spacing between tracks

  21. Water Sensing Performance • Resistivity • Varies by track spacing • Sensitivity • Varies by track spacing • Repeatability • Consistency of Result

  22. Water Sensing Performance • Sensor with 1/12’’ spaced sensor with copper chosen • More sensitive • Repeatable and consistent • Takes less space

  23. Water Sensor Design • Drop down Resistor provide current path to ground • 50Kohms chosen as the drop down resistor • Determines input to Comparator circuit • After a drop of rain

  24. Water Sensor Shematics

  25. Sensor Performance

  26. Motor Overdrive Protection • Detects if something is blocking the window • Stops operation • Receive signal from current sensor on the H-bridge • The output voltage targeted at 150mv

  27. Window Control Processor and User Interface

  28. Microprocessor • Firmware in C • PIC C CCS Compiler • Microchip’s PICkit 2 Development Board • PIC16F887 • 8-bit • Each window component described above will have its own code module • This allows for parallel development

  29. Microprocessor (cont.)

  30. Graphical User Interface • Created in Visual Studio . • Uses RS-232 serial communication to send commands and display current conditions. • Messages are one byte long in each direction. • Baud rate is 9600 • Decided not to use a parity bit.

  31. Graphical User Interface • The computer’s and the PIC’s serial ports operate at different voltages. • Computer: 8V for 0 and -8V for 1 • PIC: 0V for 0 and 5V for 1 • The MAX232 IC translates these voltage levels.

  32. Graphical User Interface

  33. Graphical User Interface • Five LEDs • Displays desired tint level. • One LED is on for 0% tint. • Five LEDs are on for 100% tint. • Three Pushbuttons • Cycle through tint levels • Open/close window • Turn on/off rain sensing feature

  34. PIC Programming • In the main loop • Check for a new serial byte. • Set desired conditions. • Set LEDs if the byte represents tint. • In a timer overflow interrupt every 65 ms • Check for buttons pressed. • Set desired conditions. • Set LEDs if the tint button is pressed. • Set LEDs if the tint button is pressed • Set LEDs if the tint button is pressed. • Wait for the button to be released before setting desired conditions again.

  35. PIC Programming • Other functions in the main loop check desired conditions, do their job, and set current conditions. • After 45 interrupts (every 3 seconds) • Place current conditions in a 5 byte array. • Send each byte with a 10 ms delay to allow the computer display to update.

  36. Acknowledgements • Masco (John Finch) • Funding • Workspace • Equipment (EE Department) • Encouragement • Dr. Natu • Project Advisor

  37. Questions and Comments?

More Related