Title of Slide

The Design of an Electronic Bicycle Monitor (EBM)Team P118:Gary BerglundAndrew GardnerEmrys MaierAmmar Mohammad

IntroductionRelevance to Dr. GibbsAvailable systemsCommercial off the shelfPhone appsElectric Bicycle Monitor (EBM)IntegrationWeightPower efficientContext of use

2Dr. Gibbs has an electric bicycle with no interfaceCommercial systems can monitor speed and battery usage, but not GPS data (in one unit)Phone apps can track location by GPS (and speed inaccurately), but not battery usageThe EBM integrates GPS, speed, and battery monitoring into one unit saving weight and power consumption.The system is to be used to monitor bike systems in real time as well as save track data for mapping later.

2RequirementsDisplaySpeed, ~20 mph maxOdometerTripDistanceMaximum speedAverage speedPeak currentTime and DateGPS position data (latitude, longitude, altitude)Battery voltage, 35 V to 40 VBattery current, up to 30 AAhr consumption since last chargeWhr consumption since last chargeRecord GPS position data for external use3System Block DiagramCaption for visual aid(s)

4MechanicsOther Option ConsideredStandard enclosureCurrent statusDonor case from GarminRoadblocksPhysical constantsPCB limit 3 1/8 X 2 SMT parts

Disassembled Garmin Nuvi 1490

5Touch DisplayOther Option ConsideredTwo Row LCDCurrent statusDonor LCD from GarminInnolux model AT043TN24Major roadblocksObtaining supporting documentationImplementing interfaceDrop-dead date: not defined yetBackup PlanSource another LCD as standby

6Removable MemoryOther options ConsideredUSB driveUSB cableCurrent StatusSD cardType not knownRoadblocksImplementing interface

7Battery Voltage SensorADCMCUBattery +Reference -AmpInternal to EBMOptionsADC (8-bit ~ 0.156 V, 10-bit ~ 0.039 V)Differential amplifierVoltage Divider8Battery Current SensorExternal to EBMIn-line with the battery positive terminalOutputs analog value for ADC directlyOptionsHall Effect sensorShunt resistor

Example of a Hall Effect current sensor.Image from: http://machinedesign.com/sensors/sensor-sense-hall-effect-current-sensors

9Wheel Speed SensorMagnetic pickupPossible Magnet LocationsExternal to EBMSends pulses to MCUOptionsMagnetic pickupOpticalRoadblocksReliabilityEnvironmentVibration

10Power Supply Requirements35-40V operational rangeBattery system providedAutomatic shutdown voltageVoltage/current sensingMultiple voltage levelsDisplay (12V?)Sensors (5V?)Microcontroller (3.3V?)Memory modules (1.8V?)GPS module (1.8V?)

11Power Supply OptionsVoltage DividerEasyMinimal partsInefficient Poor regulationLinear RegulatorSmall footprintMinimal partsGood regulationInefficientDC-DC ConverterComplicatedMultiple partsNoisyPoor regulationEfficient

12Power Supply CombinationDC-DC step downHigh efficiency (~90%)NoisyLDO filterStabilize noiseWell regulatedLDO step downEven better regulation Even better filteringLess efficiency (~70%)Voltage Step Down Scheme

13GPS Specifications:Operation voltageStarting timeInterference typeSize PriceInternal Vs. External Antenna

GPS Receiver - EM-506https://www.sparkfun.com/products/12751

14MicrocontrollerInputs and outputsInterface protocolSPI, I2C, or UART Number of ADC bitsProgram memory sizeuC architecture8 bit Vs. 16 bitDifferent Microcontrollershttp://creativeelectron.net/blog/2009/09/mcucommon-controllers-pin-configuration/

15TestingEach subsystem will be tested individuallyDivided into three parts:Testing magnetic trigger using regular bikeTesting power system, voltage sensor, and current sensor using a power supplyOther subsystem can be tested individually without any external partsFinal prototype will be tested using Dr. Gibbs electric bike

16Project Management Meeting:Bi-weekly with Dr. Gibbs (every other Thursday)Weekly with group membersDocumentation Shared folder to organized documents (Google Drive)Document naming convention for convenient accessTasks:Divided into subsystemsEach subsystem includes: choosing components, designing circuit schematics, PCB, and programmingOverlapping responsibility to help with system integration17Project Timeline (Preliminary)

Wrap Up Plan (very early)18Weekly GoalsPowerpoint Slide Assignments19

BudgetCurrently unknown, but relevant at every step in the design processSafely assumed at less than $1000 in componentsNo upper limit specified by sponsorWill factor into component selection20Conclusion/Questions21