LED Light Show Critical Design Review Team Lit Michael Hatt Scott Butler Kristin Haeusler Brock Smith

System Overview We are using a Spartan 3 controller board to output a light pattern to 4 LED boards. Each board contains 16 sets of red, green, and blue LEDs Each LED will have 8 bit varying levels of brightness (256 shades). Theoretically each set of 3 LEDs will be able to display 256^3-almost 17 million colors! (if the color blends, BIG if) 2 modes: 1. Manual-outputs one of several stored patterns chosen by the user. 2. Serial-mode-FPGA takes input from the computer and outputs a corresponding pattern to the LED boards.

System Limits The Limit of the system is the shift registers on the LED boards These boards run reliably at a speed of 5 MHz The latch rate will then depend on the amount of boards daisy chained together. For 4 boards the latch rate is 26 kHz We will go on to the section of the pattern for each LED at 101 Hz, this the is the “refresh rate” All of these frequencies are much faster than the eye can register change

Manual Mode User will choose between three pre-determined patterns. Only the initial states of the LEDs will be stored on the FPGA. The rest of the pattern will be determined by feeding the output through various logic gates and looping the new pattern back into the RAM. This way the pattern will change every cycle.

Serial-Mode FPGA will take RS-232 input, convert into usable data, and output corresponding pattern to LEDs. The user programs a pattern from a PC, we will use the hyper terminal but it could be expanded, which is then sent through a RS- 232 port to the FPGA.

System Block Diagram

Schematic of LED boards

FPGA Internal Schematic

Modularity Parts repeated for each set of boards: – Reader,Manual Writer, Switchers, RAM, LED controller, Pattern changer Single-use parts: – State Machine, Stored patterns, RS-232 Controller, Computer Writer, LCD Controller

State Machine Takes an input from user keypad – User will press button to change state (mode) Outputs the current state to nearly every block of the controller 6 states: 3 pre-programmed patterns, serial mode, initialization, and reset

LCD controller Inputs: Current State Outputs: Sends data to LCD Outputs data in ASCII format to display the current mode on the LCD, according to the State Machine.

Dual-Port RAM Inputs: RAM control signals Outputs: Data being read to LED board controller We are using two 1x1536 bit chunks of RAM (4 boards*48 LEDs/board *8 bits/LED =1536) to store patterns which are output to LEDs. Each byte of data determines the intensity/shade of each LED One half of the RAM will read in data while the other simultaneously reads out data, as determined by the switchers. Using dual-port RAM allows us to create manual-mode patterns, via the feedback loop, without having to use massive amounts of RAM to store a sustained pattern.

LED controller Inputs: Pattern data from RAM Outputs: Clock, Serial data and latch signal Takes the data from RAM. Determines if LED should get a high or low and then shifts out the correct bit. After shifting 192 bits it triggers a latch to display the pattern After 256 cycles it moves to the set of data The LED value determines the fraction of the 256 cycles that the LED will be turned on, so as to give the appropriate shade

Data Reader Inputs: Clock, Reset Outputs: Address and count information Tells RAM the address of the data that is to be sent to the LED board controller When the data is ready, a “ready” signal will also be sent to the controller Cycles through 192 addresses, then returns to first address

Example VHDL

Schematics from VHDL Schematics from VHDL

Manual-mode Writer Inputs: Pre-programmed initial-state pattern, current state, logical pattern changer. Outputs: Address info, write enable, data from input When activated by state machine, the writer takes pre-programmed pattern, then after one cycle, takes the altered pattern from the logic changer, and writes it into the RAM. Main purpose is to write new data to RAM, while other half of RAM is being displayed

Serial-Mode Writer Inputs: RS-232 data, state machine Outputs: Address, data, write enable Takes converted RS-232 input and writes it into the RAM when activated by the state machine

RAM Input Switcher Inputs: Data reader outputs, manual and serial-mode writer outputs Outputs to RAM Routes all data and signals to the appropriate half of the RAM Continuously switches between the two halves of the RAM at the correct time

RAM output switcher Inputs: Outputs of RAM Outputs: Data and control signals being read to LED controller Takes output data from RAM and outputs data from one of the two halves of RAM, in an alternating manner. Synchronous with the input switcher to assure that one chunk of RAM is reading in data while the other chunk is outputting data.

Stored Data No inputs Outputs: Data to be written to RAM Stores initial data patterns for first cycle of manual mode Only stores 4*48 bytes of data The entire duration of the pattern is determined by this initial data

Pattern Changer Inputs: Current State, Data being read to LED controller Outputs: Changed data Takes each byte being read out and changes it using pre-determined logic circuitry Prepares altered data for next cycle as previous data is being read out

RS-232 controller Inputs: Data from RS-232 port Outputs: Data(in bytes) Communicates with the RS-232 port to gather data from the computer. Converts the input data to a form that is ready to be written into RAM.

Parts List Spartan-3 Development Kit$100 PCBs(provided)~$ LEDs(3840)~$800 Optrex DCM LCD (acquired)$ Power 40 A)~$400 Resistors,etc.~$80 Shift registers~$80 Grand Total:$2117 Electricity bill to power this wall:too much

Schedule

Goals Milestone 1: – Manual Mode working Outputs changing patterns to board Intensity varies – LCD working Milestone 2: – Reading data from RS- 232 port – Mode switching works EXPO: – Serial Mode working – Can easily switch between modes – Change patterns with keypad – Documentation complete

Division of Labor Scott – RS-232 controller – RAM controllers Michael – RAM controllers – LED controller Kristin – Pattern changer – Stored pattern – RAM controllers Brock – LCD controller – state machine – switchers

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