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Capstone Fall 2009 LED CUBE. Team 8: Nate Gimple Steven Tighe Amit Halevi Noah Husek. Project Summary. LED Cube! RGB LEDs 512 LEDs, 64 microcontrollers Massively networked (64 microcontrollers intercommunicating) Uses the Atmel ATxmega64A1 Uses the Altera Nios II softcore.
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Capstone Fall 2009LED CUBE Team 8: Nate Gimple Steven Tighe Amit Halevi Noah Husek
Project Summary • LED Cube! • RGB LEDs • 512 LEDs, 64 microcontrollers • Massively networked (64 microcontrollers intercommunicating) • Uses the Atmel ATxmega64A1 • Uses the Altera Nios II softcore Noah
Project Status • Prototype boards ordered • Almost all components acquired • Microcontroller intercommunication via UART • Currently slightly under budget! • Familiarization with Nios II IDE • Familiarization with Xmega IDE Noah
Hierarchy / block diagram Nios II user input I2C module 0 super node 0 super node 1 super node 7 super node 8 super node 63 … … node 0 (LED) sensor input node 1 … node 7 Amit
Addressing 011 • Fractal • 1st digit = top or bottom • 2nd digit = back or front • 3rd digit = left or right • 000 011 100 • mod sup node • This address indicates: • Top, back, left module • Top, forward, right supernode • Bottom, back, left node • 3 bits of address: • Eases writing generic code 000 001 010 100 101 110 111 Amit
Communication Scheme Supernode Supernode Supernode Supernode Supernode Supernode Nios II I2C UART Amit
ATxmega64A1 • 32 MHz • 64 kB Flash memory • 8 USARTs • 4 I2C • SPI • Integral timers • 2 12 bit ADCs • 128 bit crypto engine! • Donated by Atmel Amit
Altera + Nios II • Master controller FPGA • Processor implemented with logic synthesis • Softcore capable of running C • I2C will be implemented in hardware, with use of extension headers on board Noah
TI TLC5947 LED Driver • 24 channels • 12 bit PWM • Serial input • Programmable constant current sink • Up to 33 V on each channel • QFN 32 • Considered discrete MOSFET drivers • Not enough ports on chip • Footprint => 2 layer • Donated by TI Noah
LEDs • RGB LED • 4 lead, common anode • Diffused epoxy • 5 mm diameter • 20 mA • Using leads as structural member • Surprisingly expensive to buy 500 Noah
PCBs • 3 kinds of PCBs • Supernode 1.7” x 1.7” • Row 0.3” x 2.0” • Column 0.4” x 3.9” • Need 64, 64, 96 respectively • All 2 layer • Supernode was originally 4 layer • Changed to 2-layer for cost • Use of QFN package LED driver allowed this Steven
Supernodes: Schematic 1 Steven
Supernodes: Schematic 2 Steven
Supernodes: Layout Steven
Rows and Columns Steven
Power Supply • Computer power supplies • Highly regulated voltage • 5 V, 3.3 V, 12 V available => 5 V used • Internal soft start • inrush current is not a problem Nate
BOM and Budget Nate
Schedule Nate
Accomplishments by CDRA review • Super-node hardware prototype • Demo firmware • 24 channel PWM • Runs simple autonomous patterns/scripts on super-node • All parts selected (sensors, LED drivers) • Know how to program Nios II soft-core (Kind of) Nate
What’s left? • Physical assembly • Kapton stencil + solder paste + pick and place = PCA • Insert through-hole LEDs by hand • Attach through-hole headers by hand • Acrylic base for structure and æsthetic • Coding • Xmega and Nios II • Basics are down, now we just need the specifics Nate
Potential Problems/Concerns • Noise on the board • Fast switching LEDs – 20 mA @ 1 kHz • Lots of serial communications everywhere • Inductive kickback • Relatively large current loops to LEDs • Communication with LED driver • SPI? • Bit-banging? • I2C capacitance • Using I2C buffer/driver (LTC4300A) • Time! Nate
Milestone 1 • PDR goals • “Puppet” mode (FPGA direct control) • More super-nodes (a full module = 8 super-nodes) • Establish intercommunication • Power supply (160 W @ 5V) • New goals • Build a supernode Amit
Milestone 2 • Full cube construction • More complex super-node autonomous scripts • Environmental input • Simple algorithmic games (GOL) • Be ready for expo Amit