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Internet Based Home Control ECE 345 Senior Design Presented By: Ken Leung Trung Lee Neil Lee
Project Introduction • Develop a web-based home control system • Focus on the control of thermostat (A/C) unit to enable user to: • View current temperature of residence • Manually turn A/C unit on/off • View and change thermostat settings
System Block Diagram
Design Of The User Interface Server Software: Apache 1.3.11 Advantages of Apache include: • conveniently downloaded from the internet • capable of running on Win32 platform • stable and robust • well documented and easily accessible resources • cost FREE!
User Interface CGI scripts: • implemented using Perl language • beneficial to learn • most commonly used scripting language • syntactically similar to Java • well documented applications and resources
Web-based user Interface
Digital Thermometer and Thermostat Dallas Semiconductor DS1620 Features: • measures temperatures from –55°C to +125°C, • which corresponds to -131°F to 257°F • temperature is read as a 9-bit 2’s complement value • data is read/written via a 3-wire serial interface using • using the CLK, DQ, RST signals • settings for thermostat mode are user-defined and • nonvolatile
Digital Thermometer and Thermostat Configuration/Status Register: • determines the method of operation • indicates the status of the temperature conversion
Digital Thermometer and Thermostat Three-wire serial interface: • Read Temperature • reads the contents of the register which contains the last • temperature conversion result • Write TH • writes to the TH register • Write TL • writes to the TL register • Read TH • reads the stored value of high temperature limit from TH register • Read TL • reads the stored value of low temperature limit from TL register • Write Config • writes configure data to configure register • Read Config • reads configure data from configure register
Device Driver Process • Provides interface between server and hardware • Works under Win95/98 • Developed in Visual C++ • Writes to ports using INP/OUTP functions • Utilizes bi-directional data port feature • Data transmitted serially on TTL outputs
Device driver features • Automatically detects port address • Detects current OS version • Detects presence of DS1620 chip • Suspend feature when chip is not active
Device Driver functions • Read Temperature (1 sec) • Write chip status (5 ms) • Read chip status (5ms) • Write trigger temperatures (5ms)
Variables in device driver • Current temperature • Trigger temperature TH, TL • Status of chip (On/Off) • Value of configuration register on chip
Potential Extensions • Interface from chip to PC using serial port • Wireless communication from thermostat chip to PC • Extend to other temperature sensitive applications (ovens, pool regulation) • Basis for home networking
Marketability • Single family homes • Electric bill savings • Convenience • Apartment Managers • supervise individual apartment temperatures • to prevent property damage