LED Light Show Critical Design Review

1
LED Light ShowCritical Design Review

• Team Lit
• Michael Hatt
• Scott Butler
• Kristin Haeusler
• Brock Smith

2
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 2563-almost 17
  million colors! (if the color blends, BIG if)
• 2 modes
• Manual-outputs one of several stored patterns
  chosen by the user.
• Serial-mode-FPGA takes input from the computer
  and outputs a corresponding pattern to the LED
  boards.

3
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

4
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.

5
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.

6
System Block Diagram
7
Schematic of LED boards
8
FPGA Internal Schematic
9
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

10
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

11
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.

12
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
  boards48 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.

13
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

14
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

15
Example VHDL
16
Schematics from VHDL
17
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

18
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

19
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

20
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.

21
Stored Data

• No inputs
• Outputs Data to be written to RAM
• Stores initial data patterns for first cycle of
  manual mode
• Only stores 448 bytes of data
• The entire duration of the pattern is determined
  by this initial data

22
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

23
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.

24
Parts List

• Spartan-3 Development Kit 100
• PCBs(provided) 650.00
• LEDs(3840) 800
• Optrex DCM 16433 LCD (acquired) 7.00
• 2 Power Supplies(5V _at_ 40 A) 400
• Resistors,etc. 80
• Shift registers 80
• Grand Total 2117
• Electricity bill to power this wall too much

25
Schedule
26
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

27
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

28
?