EE 316 Computer Engineering Junior Lab

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EE 316 Computer Engineering Junior Lab

• Digital Hangman

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Topics

• Important Specifications for the Digital Hangman
  game.
• For details read the project description
• Serial Port Software
• PS/2 Keyboards

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Digital Hangman

• Game will be played using a PS/2 keyboard
  attached to hardware
• The Personal computer will
• Randomly select word puzzles from a text-file.
• Display all correctly picked letters and
  positions of unknown letters on the LCD connected
  via a serial port.
• Keep count of the number of guesses played so
  far.
• Display messages for the player as specified in
  the game.

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Operational Characteristics of the LCD Display

• Short messages (20 or fewer characters)
• displayed instantly, left justified
• Long messages (gt20 characters)
• start at right, scroll right to left
• scroll at reading rate
• Remain displayed until next message or clear

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Software

• Standard Windows GUI (Windows XP)
• Must be able to read text-files
• Must be able to control serial port
• use the references in the Project assignment
• there are several classes (Cserial and
  CSerialPort) that are for general use
• Use them with caution
• You may want to write your own code too

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The PS/2 Keyboard

• PS/2 device interface was developed by IBM.
• PS/2 port these days use the 6-pin mini-DIN
  connectors.
• The Data and clock are open-collector with
  pull-up resistors.

http//www.computer-engineering.org/ps2protocol/
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PS/2 Keyboard, contd..

• PS/2 devices use bidirectional synchronous serial
  protocol.
• The device (keypad in this case) generates the
  clock.
• The clock frequency is 10-16.7 kHz.
• One byte of data is sent at a time.
• Each frame from keypad to the PC contains 11
  bits. These bits are

• 1 start bit. This is always 0.
• 8 data bits, least significant bit first.
• 1 Parity bit.
• 1 stop bit.  This is always 1.

http//www.computer-engineering.org/ps2protocol/
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Scan code

• Keyboards consist of a large matrix of keys
• The keys are monitored or scanned by an on-board
  processor (aka the "keyboard encoder).
• If a key is pressed, held and released, the
  keypad sends out an 11-bit Scan code (data).
• There are several scan codes. We will use the
  default code (See Scan code 2) for all modern
  keyboard.

http//www.computer-engineering.org/ps2keyboard/
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Keyboard to Host communicationThe Make scan
code for Q
1 0 1 0 1 0 0 0
Stop bit 1
Start bit 0
0001 0101 0X15 lt The make scan code for the
Q key
Parity bit
http//www.computer-engineering.org/ps2protocol/
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References

• http//www.computer-engineering.org/ps2protocol/
• http//www.computer-engineering.org/ps2keyboard/
• http//www.computer-engineering.org/ps2keyboard/sc
  ancodes2.html