N64 Controller

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N64 Controller

• EECS150 Fall2005 Lab Lecture 6
• Bryan Brady
• Greg Gibeling

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Today (1)

• Administrative Info
• Lab 4 Solution
• Project Overview
• Checkpoint 1
• Button Parse

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Today (2)

• CaLinx Expansion
• N64 Controller
• Commands
• Bit Timing
• Receive
• Transmit
• Testing

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Administrative Info (1)

• Midterm I
• Solutions are posted
• Re-grade deadline, Right Now!!!
• Group Signups
• You should already have a group
• If not, see me after class today
• Group names need to be finalized today

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Administrative Info (2)

• N64 Controller Checkout
• One per group
• Damage
• You break it, you buy it
• We dont have replacements, sorry
• Return
• Due back by the final
• Otherwise we dont grade your final

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Lab 4 Solution (1)
module Lab4PeakDetector(In, Peak, Clock,
Reset) input 30 In output Peak input
Clock, Reset wire GreaterEqual reg Peak
Lab4Comp4 C( .A( Peak), .B( In), .Gre
aterEqual( GreaterEqual)) always _at_ (posedge
Clock) begin if (Reset) Peak lt 4'h0 else
if (GreaterEqual) Peak lt In end endmodule
30 30
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Lab 4 Solution (2)

• FSM Debugging
• Both FSMs were almost Moore
• Youll build a lot of these
• Check for this CAREFULLY in your code
• Reading Logic Analyzer
• Look at the falling edges
• This avoids clock-to-output delay
• Easier to read
• CurrentState, Input, Output on THIS CYCLE
• NextState is the NEXT CurrentState

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Project Overview (1)

• Electronic Etch-a-sketch
• Knobs -gt N64 Controller
• Monochrome screen -gt Multicolor LCD
• Highlights
• N64 Controller
• NTSC (TV) Video Output
• SDRAM
• Paint Engine

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Project Overview (2)
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Project Overview (3)

• N64 Input
• NTSC Output
• SDRAM
• Paint Engine
• Paint Engine -gt SDRAM Interface

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Project Overview (4)
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Project Overview (5)

• Checkpoints
• Require more design work than labs
• Were not telling you exactly what to do
• Part of your project
• Design them well
• Test modules thoroughly!
• Dont lose your code
• Require more time

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Checkpoint 1 N64 (1)

• Primary input for your project
• Direction Buttons Move cursor, paint
• Analog Joystick Move cursor, paint
• Other Buttons
• Change color
• Change brush size
• Extra features, bells and whistles

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Checkpoint 1 N64 (2)

• I/O Controller
• Precise timing requirements
• You have to match a real piece of hardware
• You cant change both ends of the problem
• Hard to simulate
• You may want to build a model controller
• We would give you one, but its basically the
  solution with minor changes
• Hint hint

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Button Parse (1)

• Real World Inputs
• Problem
• Circuits are fast (27MHz)
• Humans are slow (100Hz)
• Mechanical switches are very imperfect
• Solution
• Take very long (10ms), very bouncy pulses
• Clean them up
• Generate one cycle pulses (1b0, 1b1, 1b0)

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Button Parse (2)
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Button Parse (3)
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Button Parse (4)
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Button Parse (5)
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N64 Controller (1)

• Functionality
• Fancy Parallel lt-gt Serial Conversion
• Single bi-directional wire to N64 Controller
• Core of this module is a Shift Register
• Polling
• N64 uses Challenge/Response
• We send a command, it responds
• Might need a little state (send/receive)

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N64 Controller (2)

• Construction
• Components
• Shift Register
• FSM/State Register
• What else?
• Plan your design out in DETAIL

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N64 Commands (1)

• Available Commands
• 8hFF Reset Controller
• 8h00 Get Status
• 8h01 Read Buttons
• 8h02 Read Mempack
• 8h03 Write Mempack
• 8h04 Read EEPROM
• 8h05 Write EEPROM

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N64 Commands (2)

• Command Format
• 8bits of Command
• 1-bit Stop Bit (1b1)
• Example
• Read Buttons 9b000000011
• How do we generate this?
• Shift Register
• Something better

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N64 Bit Timing (1)
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N64 Bit Timing (2)

• Read Buttons Command
• 8bits of Command 8h01
• 1bit Stop Marker 1b1

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N64 Receive (1)

• Points to Consider
• Reliability
• The N64 controllers are NOT 100 reliable
• Your circuit must be
• Timing
• This is not a synchronous design
• The controller has its own clock
• We must detect new bits
• A major part of this design is timing!

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N64 Receive (2)

• Detecting a new bit
• Look for 1b1 (Stop sub-bit) -gt 1b0 (Start
  sub-bit)
• Falling Edge Detector
• Wait 1us
• Capture Data

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N64 Receive (3)

• What if we never get another bit
• Detection
• Falling edge never happens
• How do we detect an event that never happens?
• Recovery
• Cant wait forever, game will lock up
• Should reset the controller
• Should re-request the button status
• You MUST recover from this condition!

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N64 Transmit (1)

• For Each Bit
• Count 1us (1 sub-bit), Transmit 1b0
• Count 1us (1 sub-bit), Transmit Data
• Count 1us (1 sub-bit), Transmit Data
• Count 1us (1 sub-bit), Transmit 1b1
• Timing
• Were driving the bus not a problem
• Still very important

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N64 Transmit (2)
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N64 Testing

• Required
• Your circuit must work on board reliably
• Look at our demo
• Recommended Testing
• Build a testbench model of the controller
• Symmetric Protocol
• Bits out look like bits in
• Just a different number of bits
• Modify your solution