1. Project Goals Our task was to take the proof of concept and make a production ready prototype with the following parameters Use low cost microprocessor Add RS-232 I/O functionality Implement identical logic of original system Replace variable resistors with software timers Maintain all other specifications Preserve existing product housing Keith Benson – President, Bonitron Inc. Stephen Collings – Engineer, Bonitron Inc. Dr. Andrew Dozier – EECS Professor, Vanderbilt University System DiagramPCB Design Introduction Sponsors Bonitron HVAC Demand Scheduler Alexander Brown (EE) – Cory Haugh (EE) – Ajmer Dwivedi (ME) Problem Bonitron ceased producing the device when the microcontroller that it used went out of production. Last year, a design team successfully documented all the components used in the original demand scheduler. They also generated system diagrams, circuit schematics, and logic diagrams corresponding to the original design. This year our goal was to engineer a production ready prototype and deliver it to Bonitron. The Bonitron HVAC Demand Scheduler is a device that reduces the peak power consumption in a building running two HVAC units. It interfaces with the thermostats and only allows one unit to run at a time (unless a user overrides this functionality). By lowering peak power consumption the demand scheduler can drastically lower utility bills. Proof of Concept Designed Last Year Four main functions: Power conversion, signal conversion, RS-232 communications, and microcontroller Demands from the thermostats are routed to the microcontroller. The microcontroller's decision to activate a unit is based on parameters set by the user Microcontroller Selection NameCyclone II FPGAHCS1287C51PIC16F747 Part NumberEP2C35F672C8NMC9S12UF32P87C51FB-4NPIC16F747 ProducerAlteraFreescaleNXPMicrochip Unit Cost$99.70$4.20$7.80$3.20 Package672-FBGA64-LQFP40-PDIP Programming SoftwareQuartus IIMGTEK MiniIDEThird PartyBundled with PicKit Cost0.00 Programming HardwareSerial Port CableUSB CableZIF Socket + USBPicKit 2 Cost$150.00$100.00$110.00$50.00 Programming LanguageVHDLAssembly \ CAssemblyAssembly \ C Custom HeaderYYNY TimersNYYY RS-232NYYY Internal ClockNNYY Non-Volatile CodeNYYY Notes: Previous group’s FPGA, used in FPGA class at Vanderbilt Used in microcontroller class at Vanderbilt Microcontroller currently used in Bonitron BoardLowest Cost to Project Development Approach Use PICkit 2 development environment  Hardware programmer for PIC microcontrollers  USB programmable  Connects via 6 pin header on PCB  Packaged with starter kit for testing Copied 90% from previous PCB layout Added connections for new microcontroller and serial communications 2 sided through hole design allows easier trace routing than previous single sided board PCB floorplanPCB trace layout Graphical User Interface GUI controls timers and overrides  Parallels functionality of previous override design  Replaces variable resistors with programmable timing capabilities Allows user to program timers without physically manipulating components Tested using feedback loop GUI Testing Using Feedback Loop Assembly and Testing PCB fully assembled and functional GUI functional and communicating with PIC16F747 microcontroller