Analog A2D Design

Nuclear A2D DesignCritical Design ReviewGroup #09Kristen BermanJoseph NicholsCassandra ToddMichael ZellarsK1Project MotivationOur group wanted a mentor/project sponsorshipACTIVE Lab (Applied Cognition and Training in Immersive Virtual Environments) has a partnership with the NRC (Nuclear Regulatory Committee) Nuclear power plants primarily contain outdated technologyThe ACTIVE group will use our device to test a transition from analog to digital control technology

K2Goals and ObjectivesCreate a working hard and soft panel that will support the ACTIVE group in their testingHard panel will consist of an extensive PCB design, multiple types of analog controls and needs to establish and maintain connectivity to the soft panelSoft panel will be an accurate representation of the hard panel and needs to both accept inputs and send outputs to the hard panelIn addition needs to establish and maintain connectivity with both the hard panel and the power plant simulatorWe want to try to keep the hard panel to a reasonable sizeK3Specifications & RequirementsHard Panel will consist of about 100 components (switches, push buttons, gauges and LED sectors)Analog controls (Push buttons and switches) will need to be able to indicate current statusPower protection circuits will keep the panel temperature low and noise level maintainedEach device will be labeled with a 7 character alphanumeric stringBoth panels need to be user friendly to appeal to the novice user but still remain customizable to adapt to the different testing environments needed by the ACTIVE groupAll components will reside in a LANSoft panel will use UDP transmissions to communicate with the Power Plant Simulator

K4System Block Diagram

J5MicrocontrollersMaster/Slave ConfigurationOur Master MCU will control two Slave MCUsMaster MCU ATmega325 (used for overall control as well as push buttons & rotary switches)Slave #1 MCU ATmega8 (used for control of gauge subsystem)Slave #2 MCU ATmega32 (used for control of LED subsystem)Serial Peripheral Interface was chosen to execute this configurationMaster will utilize SPI to transmit/receive data from the 2 slaves

J6MicrocontrollersAVR ProgrammingAVR Processors use RISC architecture computers we will be using will run either x64 or x86 so a cross compiler is necessaryTo implement this we will use Atmel Studio 6 for Windows PCs as well as the command line program AVRDUDEWe will also use an Arduino Uno to program our AVR microcontrollersThis supports in-system programming while designing our circuitAlso, Arduino offers ArduinoISP firmware which provides us with tutorials and code to burn a bootloader onto an AVRJ7MicrocontrollersCommunicationIn order to establish a connection between the Master MCU and the soft panel we will use the RS232 serial data standard

Housing UnitWill require Acrylic and Sheet MetalNeed to make sure to have smooth edges (no hazards)Acrylic will be used for casings around the gauges and the LED boxMetal will be used for the overall housing unitPositioningLight box sector needs to stretch across the topAll other devices will be grouped together

Analog Controls

K10Analog Controls

26 Push Buttons have been purchased in both Red and Green colors and 25 Rotary Switches have been purchasedThese items will be connected directly to the Master MCU and main PCB boardDue to their purely analog nature, they require status LEDs to indicate connectivity to the Soft PanelK11Analog Controls

Gauge Design

M12Detailed Gauge Design

3D Print JobCustom needle design via SolidWorks

24 needles to be printed

Material cost at $0.35 / cm3 $5.09

Analog Controls

LED Box Design

C15Hardware Block Diagram

C16Power CircuitDesign RequirementsSolutionPlug and play Take power directly from wall outletOperating Voltages 3-5VDCAC-DC buck boost converter Isolated sourceChopper circuit and feedback controller

C17Printed Circuit Board DesignEach subsystem will be placed onto its own PCB3 boards in total will be designedMaster MCU, power circuit, rotary switches and push buttonsGauges subsystemLED subsystemSeparating into subsystems cuts down on issues to potentially be found and will hopefully make testing each subsystem easierAll PCB work will be designed in EAGLE design software and sent to a manufacturer for assembly18Software Block Diagram

M19Soft PanelThe GUILED sectorSwitchesGaugesPush Buttons

LED Sector

Three states:OnOffFlashingSwitches

Lever is moved by clicking and dragging

Status LED indicates on or off

Gauges

PrecisionSmooth movementPointer acceleration and deceleration will be implemented in the futurePower Plant SimulatorJava-based application running on a separate PCHandles user input Button pushingSwitchingReturns output to control panels Change in gauge statesChange in LED states

UDP Multicasting

Power Plant Simulator sends each output command with a UDP multicastThis means that every control panel within the network receives the same transmissionMulticasting is used to keep network traffic minimal and ensure the system is in syncDesign Decisions4 Layer PCBMost important decision for a PCB is the number of layersThe 2 PCBs that support the gauges and LED subsystems will each be double-sidedThe 3rd PCB will have a more complex design and will therefore require more layers2 signal layers, a ground layer and a power layer

Design DecisionsMicrocontrollersOur hardware design is centered on the ATMega series of microcontrollersThe table outlines the 3 microcontrollers that were selected and key characteristics

Design DecisionsPower circuitIsolated Flyback Buck Boost ConverterIndustry StandardCan Perform both buck and boost operationsMore efficient designBetter at conserving energyCapable of storing energy during on state of system

Current Successes & DifficultiesWorking Gauge Prototype90% of parts are orderedTentative Soft Panel LayoutStaying under budget

PCB Accuracy Fear of a shortGeneration of excessive heat during the DC-DC transformationMain regulated voltage wont be 3.3V @350mAPotentially might need an LED driver to provide a constant current source

Project BudgetItemQuantityCostPurchased?Push Buttons26$39 Switches25$172.50 Stepper Motors25$70 Shift Registers15$7.20 Light Box LEDs25$18.50 Indicator LEDs26QuotingXMCUs9Free PCB4 Layers$200XHousing Unit Metal & AcrylicQuoting$70XElectrical ComponentsVarious$80 Cords3$45 Electrical Grounding Equipment3$20 Total Funding Allotted: $991.25Total Amount Spent: $493.32Amount Projected Left to Spend: $335Amount Estimated to Save: $162.93Work RolesTeam MemberWork DistributionKristenSystem Communication & Administrative ContentJoePrimary PCB Design & MCU ConfigurationCassiePower Circuit & LED Circuit DesignMikePrimary Software Engineer & Gauge DesignCurrent ProgressImmediate PlansAiming to have PCB orders in by January 31stWill finish up remaining part orders by the 31st as wellFebruary will transition into a coding focus MCU & Soft Panel

Special Thanks

Questions?Rectifier and Filter

Chopper

DC-DC Transformer

Output Rectifier and Filter

Feedback Controller

AC In

DC Out

DC

DC Out