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ECE 477 Design Review Team 8(SLOW) Spring 2006. Ayush,Varun,Randall, Bank. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout Software design/development status
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ECE 477 Design Review Team 8(SLOW) Spring 2006 Ayush,Varun,Randall, Bank
Outline • Project overview • Project-specific success criteria • Block diagram • Component selection rationale • Packaging design • Schematic and theory of operation • PCB layout • Software design/development status • Project completion timeline • Questions / discussion
Project Overview • Designing an LED panel by cascading 10 5x7 LED dot matrices. • A built in embedded server on the microcontroller to edit/display text messages on the LED panel via a website. • Scrolling feature to display long text messages. • Allows users to display the outdoor temperature using a temperature sensor. • Display current time using a highly accurate internal clock.
Project-Specific Success Criteria • Ability to display ASCII character strings on an LED matrix. • Ability to save messages and configuration data in non-volatile memory. • Ability to measure and display the outdoor temperature. • Ability to display the current time (based on highly accurate internal clock). • Ability to configure display and edit messages via an embedded server.
Component Selection Rationale Microcontroller : Must have a timer module for the clock, a ATD port for the temperature sensor, built in ethernet controller, PWM module. Choices : Freescale MC9S12NE64CPV • 80 pin package, 38 I/O pins and 10 input only • 64K of FLASH memory • ATD ports • Timer Module • A IEEE 802.3 compliant ethernet controller Rabbit RCM 3750 • 33 I/O pins • Built in Ethernet Controller • 512K of FLASH memory We decided with the MC9S12NE64CPV as it has a low cost, easily attainable and has a enough number of input output pins. Also, the MC9S12NE64CPV has good documentation as compared to the Rabbit microcontroller.
Component Selection Rationale LED Driver Toshiba TB62708 with a 16 bit shift register and latching ability • Low cost • Programmable Output current from 5mA to 90mA • Current sourcing device We required a 12 bit shift register for our design but we could only find current sinking ones. ULN2003A Darlington Array • 16 Bit package • Sinks upto 500mA of current( our sink current came upto 105mA) • Recommended by our TA Brian as used by him for one of his LED projects RJ45 Jack • Recommended by the microcontroller data sheet
Packaging Design Considerations : • LED’s panel is big enough and can be seen from a distance of up to 30 feet. • Aluminum Case • Weight estimation : around 3.4 lbs and mountable on a wall. • Dimension is 17” x 4” x 3”
Schematic/Theory of Operation • Total Parts : 88 17 Capacitors 2 Diodes 25 Resistors 3 Switches 1 crystal 10 LED drivers 10 Darlington transistors 2 Inductors 10 LED displays 1 Microcontroller 2 Power Regulators 1 RJ-45 1 BDM 1 Header 1 Temperature Sensor 1 12V Power Adapter
Software Design/Development Status • All programming and decoding will be done on the Microcontroller • Even without the PCB, MC9S12NE64 Development board can be used to write code and test our components. • LED matrices are driven by column therefore making it possible to control text scrolling.
Project Completion Timeline • Week 8 (This week) – Finalize PCB / Design Review • Week 9 – Start Software Development / Final PCB Modification • Week 10 – Testing hardware / Continue Software Development • Week 11 – Continue Software Development / Testing PCB Functionality • Week 12 – Finalize Software / Debugging • Week 13 – Packaging / Testing / Debugging • Week 14 – Final Tweaking • Week 15 – Documentation / Prepare for Final Presentation • Week 16 – Final Presentation