Slide 1IntroductionDescriptionRelated WorkMore Related WorkHardware DesignHardware cont.Schematic – Sheet 1Schematic – Sheet 2Board LayoutSoftware DesignResultsChallengesBudgetDemoFuture WorkConclusionQuestionsEnviroSenseJonathan MohlenhofEEL6788 - Team 1604/20/2011Hardware project focused on interfacing external sensors to mobile devicesExpands variety of sensors available to developers for urban sensing applicationsCurrent sensors available on mobile devices are few, restricted to UI and location functionality:◦Multi-touch, accelerometer, compass, GPS, microphone, cameraAdding new sensors allows researchers to expand on experimentsIntroductionAdd environmental sensors to iOS deviceCustom designed PCB that interfaces between iOS device and sensorsAbility to sense:◦Temperature◦Humidity◦Barometric Pressure◦Carbon Monoxide (CO)◦Carbon Dioxide (CO2)◦Ozone (O3)◦General Air QualityDescriptionCommon Sense: Mobile sensing for community action◦http://www.communitysensing.org/◦Self-contained, built in:GPRS Modem, GPS, Bluetooth, sensors, batteryMote Platform◦http://www.eecs.berkeley.edu/~prabal/projects/epic/◦Large developers communityRelated WorkThe Urban Pollution Monitoring Project◦http://www.equator.ac.uk/index.php/articles/563◦Self contained system◦Older systemAir: Preemptive Media Project◦http://www.pm-air.net/index.phpMore Related WorkSensors◦SENSIRION - SHT15Temperature and HumidityTwo Wire Interface (TWI)◦VTI Technologies – SCP1000Temperature and Barometric PressureSerial Peripheral Interface (SPI)◦MQ-7 CO Gas Sensor◦MG811 CO2 Gas Sensor◦MQ135 Air Quality Sensor◦MQ131 O3 Gas SensorHardware DesignRequired custom printed circuit boardMicrocontroller Atmel Atmega328P to interface to sensors and iPadConnects to iPad via 30 pin connectorTx – pin 12, Rx – pin 13Powers of of 3.3V from iPadHardware cont.Schematic – Sheet 1Schematic – Sheet 2Board LayoutMicrocontroller programmed in CUtilizes libraries to interface with sensorCommunicates using serial to iPad with SLIP protocol and Zebulon MCU Message LibraryiPad application is programmed in Python◦Utilizes built in serial library◦Required iPad to be rootedSoftware DesignBoard works!Able to achieve 1 Hz update rate from sensorsLow power consumption◦3.3V@30mA◦100mWDoes not severely impact battery life, not ran in backgroundResultsWas unable to access serial port through Apple iOS SDK, found diferent method through PythonUnable to refresh GUI display continuously, receives sensor data once at startupGas sensors are not factory calibrated, unable to map the sensor value to a PPMHardware required some debuggingChallengesPart Vendor CostPCB Gold Phoenix $50.00Atmega328P Mouser $4.18CO2 Futurlec $19.90CO Futurlec $8.90O3 Futurlec $12.90Air Quality Futurlec $6.90Barometric Pressure Sparkfun $24.95iPod Connector Sparkfun $4.95Humidity / TemperatureSparkfun $28.95Misc - $20.00Total $181.63BudgetShow GUI AppShow CLI with continuous updatesDemoIncorporate pushing data to central server for sharing with community◦Research diferent available frameworks with built in security and functionalityLog data with timestamp and location information (GPS not available on my iPad)Add filters for noise on sensorsGraphing capabilityWireless connectivity to sensor board over BluetoothMore general open source hardware to allow interface to other sensorsFuture WorkUtilizing users’ mobile devices for the UI and network connectivity can make the sensor board cheaperOpening up hardware from mobile device manufactures would make integrating these technologies simplerGeneral purpose hardware boards could revolutionize mobile sensing and researchNot restricted to sensor
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