ECE 477 Design Review ECE 477 Design Review Team 3 Team 3 Spring 2009 Spring 2009

OutlineOutline• Project overview Project overview • Project-specific success criteriaProject-specific success criteria• Block diagramBlock diagram• Component selection rationaleComponent selection rationale• Packaging designPackaging design• Schematic and theory of operationSchematic and theory of operation• PCB layoutPCB layout• Software design/development statusSoftware design/development status• Project completion timelineProject completion timeline• Questions / discussionQuestions / discussion

Project-Specific Success CriteriaProject-Specific Success Criteria

Propel a projectile from the coil gun.• Operate with at least one coil at fire time.• Report charge status and readiness.• Measure and report transient properties

(such as muzzle velocity) of the projectile.• Track and Display.

Project OverviewProject Overview

• Multi-stage coil gun capable of propelling Multi-stage coil gun capable of propelling ferric projectilesferric projectiles

• Driven with 9v battery and includes battery Driven with 9v battery and includes battery backupbackup

• Report transient properties of projectile to Report transient properties of projectile to LCDLCD

Block DiagramBlock Diagram

Component Selection RationaleComponent Selection Rationale

• Microcontroller Constraints:Microcontroller Constraints:– Fast computation speedFast computation speed

• Projectiles will hopefully be going fastProjectiles will hopefully be going fast• Short distance between sensors and from sensors to Short distance between sensors and from sensors to

coilcoil– Large number of external interrupt pinsLarge number of external interrupt pins– 6 ADC channels6 ADC channels– Good supportGood support– Large amount of FlashLarge amount of Flash– 1 SPI port1 SPI port

• Switching transistor constraints:Switching transistor constraints:– Very high Collector-Emitter currentVery high Collector-Emitter current– Fast switching timeFast switching time

Component Selection Rationale

• PIC32MX360F256L– 80MHz, 125 MIPS– 256 KB Flash– 22 Interrupt-on-Change pins– Up to 16-channel 10-bit ADC– Excellent Support– 256K Flash– 2 SPI ports, various other serial protocols

• IRGPS60B120KDP IGBT– 104 Amps ICE

– 50ns switching speed

Packaging DesignPackaging Design

Schematic/Theory of Operation 1Schematic/Theory of Operation 1

Schematic/Theory of Operation 2Schematic/Theory of Operation 2

PIC Microcontroller

PICTop View

PICLeft View

PICBottom View

LCD & PIC - Right View

3.3V Buck/Boost

Coil Discharge Circuit

Coulomb Counter

PCB Layout ConsiderationsPCB Layout Considerations

• 4 PCB total: 1 main and 3 smaller discharge 4 PCB total: 1 main and 3 smaller discharge circuit PCBscircuit PCBs

• EMF protection to circuitryEMF protection to circuitry– ~5v measured EMF around single coil~5v measured EMF around single coil– Faraday cage around all coilsFaraday cage around all coils

• Large trace widths to power and ground for Large trace widths to power and ground for coil discharge circuitcoil discharge circuit

• Main PCB width to remain under 3” to fit onto Main PCB width to remain under 3” to fit onto rifle. More leeway with PCB length.rifle. More leeway with PCB length.

PCB – Main Board

PCB - PIC

PCB - LCD

PCB – Power Circuit

PCB - Component Layout

PCB - Component Layout

PCB - Component Layout

PCB - Component Layout

PCB Discharge Circuit

PCB Discharge Circuit

PCB Discharge Circuit

PCB Discharge Circuit

Software Design/Development StatusSoftware Design/Development Status

• DesignDesign– Timer interrupt to handle LCD updates via SPITimer interrupt to handle LCD updates via SPI– External interrupts to handle push buttonsExternal interrupts to handle push buttons– Input capture to handle optical sensorsInput capture to handle optical sensors– Calculate velocity based on distance/time Calculate velocity based on distance/time

between sensorsbetween sensors– Output compare to handle trigger timingOutput compare to handle trigger timing– Final timings = velocity calculation + empirical Final timings = velocity calculation + empirical

observationobservation• Development Status:Development Status:

– Learning development toolchain/examplesLearning development toolchain/examples– Somewhat familiar with architectureSomewhat familiar with architecture– Not anticipating many problemsNot anticipating many problems

Project Completion TimelineProject Completion Timeline

Questions / DiscussionQuestions / Discussion

Optional Camouflage Painting, $30