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eHVAC: Wireless Modular Multi-Zone HVAC ControllerGroup 14

Michael Trampler EEJavier Arias EE Ryan Kastovich EE Genaro Moore EEOverviewHeatingVentilationAir ConditioningSome provide advanced features such as humidity control and CO2 monitoring/controlScheduling and adaptive set-points will allow the user to reduce the systems run time.Run time data logging will give the user a better understanding of the systems activities

MotivationIncreased cost of electricityGreat cost of commercially available HVAC controllers Limited feature set of commercially available HVAC controllers, especially web enabled controllers

ObjectivesAccurately read temperature and relative humidity both inside and outside building.System management through web appScheduling capabilities CO2 monitoring for a gauge of air qualityZone controlExpandable to multiple zonesWireless connectivity to RSMReduction of energy consumption due to scheduling and set-point controlSimple and easy installation with minimal wiring.

Project SpecificationsMain Controller Control up to 8 zonesWireless connectivity to RSM at a minimum of 50ftWeb InterfaceHost at least 5 users simultaneously Manage week long schedules for each zoneTrack duty cycle of heat pump to an accuracy of 0.1%Display status of up to 8 zones simultaneouslyRSMTemperature 0.125CHumidity 5% relativeCO2 At least 500 ppm1.5 month battery life

System Block DiagramPlant Block Diagram

0000Plant SpecificationsNeed to supply 24VAC to drive the different components

Be able to support up to 8 zones

Continuous uptime for 2 months

Heat PumpVarious types: single stage, multi-stage, variable compressor, variable fan, oil, gas, etcDesign for single stage because most common in FLAir handler indoors, compressor outdoors

Heat Pump ComponentsReversing Valve (changeover)Controls heating/cooling mode Compressor Supplementary heat Electric heating coilsFan (Air Handler)Automatic turns on when ever the whole unit is onON (continuous) on regardless of the state of the unit

Control (Hardware)74HC595 (from TI)8-bit serial input shift registerSerial or parallel outputVcc: -0.5V - +7VNeeds only 3 inputs: data, latch, and clockOutputs 0 Vcc (V)

11Control (Hardware) ContinuedMAC97 TriacConnected to 24VAC supply to drive the heat pump componentsCan handle up to 600V2V max gate trigger voltage0.66V typical trigger voltage

Heat Pump Control SchematicPlant Block Diagram

0000Damper ControlDampers act as a door for air to flow through ductsDampers come either N-O/N-CRequire 24VACUtilize normally open 2 position dampersMakes system modularDesign for up to 8 zones74HC595 Shift Register8 outputs for 8 zonesMAC97 Triacs8 triacs for the 8 zones

Damper Control SchematicOutput BoardThe plant control will be implemented onto a PCB separate from the Main Control UnitResponsible for shift register and triac controlIt will communicate wirelessly between the output board and the Main Control Unit1 MSP430 will be utilized to drive the shift registers

Output Board SpecificationsMSP430G25531.8 3.6 V supply230uA active consumptionDrives triacs and shift registers

74HC595 Shift RegisterMAC97 TriacsUART connectivity to Wireless Module

Main Control Unit (Hardware)Control software of the plant will be housed in the MCUOnce the state of the HVAC system is determined, the MCU will send the state to the Output Board which will take care the restAlso in charge of gathering data from the Remote Sensor ModulesCommunicates with Web AppStellaris LM3S8962 Microcontroller

System Block DiagramTemperature/ Humidity HardwareUsing a digital Temperature/Humidity Sensor from HoneywellHIH-6130Accurate to 4% RHOperates from 0-100% RHAccurate to .025 CSPI3.3V supply0.6-0.75mA current consumption

CO2 MeasurementMC811Low cost CO2 measurement Analog output voltage which requires amplificationSensitive from 250ppm to 10000ppmRequires 200mA at 6V

LMC660Very High input impedance FET op-ampUsed to amplify the output to a usable level for the microcontroller

User InterfaceOne 1.8 inch TFT color display16 bit color resolution160 x 128 pixelsSPI interface4 push buttonsUsed for simple input

Wireless Communication SpecificationsMSP430G2553UART Connectivity to modulesCC110L Transceiver Anaren booster packFrequency Band: 779 928 MHz200nA sleep mode consumptionSPI connection between transceiver and MSPCreates single code base for wireless communications

System Block Diagram

Stellaris Internet ConnectivityModified lwIPhttpd (web server) implementation provided with Stellarisware.

CGI adapter provided by Stellarisware sample code.

unsigned long FindCGIParameter(const char *pcToFind, char *pcParam[], int iNumParams)Searches the list of parameters passed to a CGI handler and returns the index of a given parameter within that list.

long GetCGIParam(const char *pcName, char *pcParams[], char *pcValue[], int iNumParams, tBoolean *pbError)Searches the list of parameters passed to a CGI handler for a parameter with the given name and, if found, reads the parameter value as a decimal number.

unsigned long EncodeFormString(const char *pcDecoded, char *pcEncoded, unsigned long ulLen)Encodes a string for use within an HTML tag, escaping non alphanumeric characters. This function encodes a string, adding escapes in place of any special, non-alphanumeric characters.

unsigned long DecodeFormString(const char *pcEncoded, char *pcDecoded, unsigned long ulLen)Decodes a string encoded as part of an HTTP URI. This function decodes a string which has been encoded using the method described in RFC1738, section 2.2 for URLs.

Web App HostingStellaris LM3S8962BeagleboneGoogle App EngineClock Frequency50 Mhz720 MhzN/ARAM64 KB SRAM256 MB DDR2N/AStorage256 KB Flash + microSDmicroSDN/AEthernetYesYesN/AOperating SystemNoneLinuxN/AHTTP ServerC (Custom coded using lwIP)Apache/LighttpdN/AApplication ProgrammingCC/Python/PHP/Perl/JavaPython/Java/GoData storageCSVCSV/SQLDatastoreCost~$90 (dev board)~$90 (dev board)N/AEnd-to-End ConnectivityWeb App HostingGoogle App EngineCloud computing: Platform as a serviceHosting on Google's infrastructureGoogle Cloud = Distributed resourcesNo need to manage serverApplication development:PythonJavaData storage: Google Datastore

Python/ JavaPythonJavaIs it Free?Free and Open SourceFree and Open SourceLearning CurveSimple SyntaxLacks Simple SyntaxDoes it need to compile?NoYesOther tools?Wide range of tools and librariesLarge range of librariesBuilt In Docs?YesNoScript?YesNoDifficulty of Implementation in the Google App EngineVery straight forward implementationNot very straight forward

Webapp2Lightweight frameworkFlexible and easy to extendBuilt into Google App EngineWSGI AdapterInterface between web server and web applicationAlso responsible for handling uncaught exceptionsTemplatingHTML embedded in code is messy and difficult to maintain.Using a templating system we can dynamically generate portions of the HTML and embed special placeholders in the HTML files to indicate where the generated content should appear.Django templating engine

Webapp2 Handlershandlers.ReadingsHandlerhandlers.ZonesHandlerhandlers.UsersHandlerhandlers.PlantsHandlerhandlers.SchedulesHandlerhandlers.ThermostatsHandlerhandlers.LoginHandlerhandlers.ReportsHandler

Google DatastoreHorizontally distributed database based on Google's BigtableManages very large sets of structured dataAllows for scaling of applications as they receive more trafficObject datastore Objects are called entitiesEntity kinds (classes) Modeled in Python or JavaSupports atomic transactionsPython and Java APIsGoogle Query Language: flexible but not as much as SQL

Data ModelsEvery entity has its own unique key propertyImplicitly created by the App Engine during entity creation.Includes the entity kind and a unique numeric ID that is automatically assigned.

System Block Diagram

Operating EnvironmentDevelopment Platform:Google App Engine

Backend Programming Language:Python

Primary Client-Side Scripting Framework:jQuery Mobile (JavaScript)

Why jQuery Mobile?HTML5 and CSS3 CompatibilityWorks on both Android and iOSProfessional Layout for PC, Tablet and Mobile DevicesCompatibility with Firefox, Chrome, Safari and others

Allows for rich touch screen interfaces for mobile devices

Simple SplitviewjQuery Mobile plugin which utilizes white space by splitting the menu options on the left side and the displayed selection on the right

A PC/ Tablet layout will have a split in the middle between these two parts of the web app to fill in the white space

A Mobile layout will fit the menu options to the screen and upon user interaction will display the data PC/ Tablet Landscape View

Mobile View

Web App Use Case Diagram

SchedulerStandard HVAC systems typically do not include embedded schedulers for their users

User will be able to adjust Set times, Humidity and Temperatures for specific zones in the system

Users will be able to adjust their scheduler for a week at a time

Coded using Python and JavaScript

Output Power SupplyUse readily available 24VAC supplyMost commercial HVAC controllers use a 24VAC supply as standardOutput 24VAC for HVAC system controlUse Full Wave rectifier and 3.3V switching regulator for logic level power

OKI-78SR-3.3DE-SW033TPS62111RInput Voltage Range7-36V5-30V3.3-17VEfficiency75-90%83%80-95%Current1.5A1.0A1.0aCost$4.35$15.00$3.7243Main Controller Power SupplyUse readily available 17V Laptop power supply3.3V switching regulator for logic level power

OKI-78SR-3.3DE-SW033TPS62111RInput Voltage Range7-36V5-30V3.3-17VEfficiency75-90%83%80-95%Current1.5A1.0A1.0aCost$4.35$15.00$3.7244RSM Power Supply RSM will use 4 AA batteries to supply the CO2 sensors heaters, as well as the op-amps Vcc3.3V regulator will be used for the sensors, the wireless communication and the main microcontroller

ProgressProject DistributionMichaelJavierRyanGenaroPlant Control5%15%5%75%RSM85%5%5%5%Database5%55%35%5%Web App5%35%55%5%PCB75%5%5%15%BudgetItemQuantityPrice (of each)Expected BudgetBudget so FarSensor Microcontroller8$1.00$8.00$0.00Humid/ Temp Sensors4$15.00$60.00$20.00CO2 Sensors4$20.00$80.00$40.00Graphical Display Unit(s)4$20.00$80.00$30.00Input Peripheral Suite4$5.00$20.00$10.00RSM Power Supplies4$10.00$40.00$10.00Main Controller Power Supplies1$15.00$15.00$20.00RF Module6$15.00$90.00$70.00PCB5$33.00$165.00$165.00Main Controller2$100.00$100.00$100.00Triacs16$2.00$32.00$20.00Grand Total$690.00$485.00Issues/ ConcernsWireless Node LimitCollision During Wireless TransmitDuplicity of commands from Google App Engine to StellarisDesigning a SchedulerNo touch event response on Google Chrome

Questions?