1. 1 COMP541 Input Devices: Keyboards, Mice and Joysticks Montek Singh Apr 16, 2012

2. Keyboard Interface

3. 3 PS/2 Keyboard  Uses a synchronous serial protocol What does that mean? What does that mean? Each symbol is transmitted bit-by-bit Each symbol is transmitted bit-by-bit  8 data bits + 3 control bits

4. 4 Physical Interface  Two lines Clock (15-20KHz) Clock (15-20KHz) Data Data Normally high, asserted low Normally high, asserted low  Read: pp 13-14 of Nexys 3 manual pp 13-14 of Nexys 3 manual

5. 5Protocol  Bidirectional Kybd-to-host and host-to-kybd on same wires Kybd-to-host and host-to-kybd on same wires  CAPS LOCK light for example  Assert low To send, keyboard starts clocking To send, keyboard starts clocking  sends successive bit on positive edge of clock  host reads bits on negative edges of clock  You shouldn’t need to send to kybd

6. Protocol  11 bits a start bit: always 0 a start bit: always 0 8 bits of data 8 bits of data  lsb first one parity bit (odd) one parity bit (odd) a stop bit: always 1 a stop bit: always 1  Clocked by keyboard Value should be latched by FPGA on neg edge of keyboard clock Value should be latched by FPGA on neg edge of keyboard clock 6 Illustration from http://www.beyondlogic.org/keyboard/keybrd.htm

7. 7 What is Sent  ASCII is not sent!  Scan codes for keys Most keys have an 8-bit (single byte) scancode Most keys have an 8-bit (single byte) scancode Some have two bytes Some have two bytes A few have even more! A few have even more! Most (not all, be careful!) keyboards use these scancodes: Most (not all, be careful!) keyboards use these scancodes: Illustration from Nexys 3 manual

8. 8 Scan Codes  Normally translated by software You remap your keys, for example You remap your keys, for example  Software takes care of Shift, caps lock, control Shift, caps lock, control

9. 9 Some Scan Codes Long  Two code sequence common Have a look at Break key! Have a look at Break key!

10. 10 Even More Complicated  Scan code generated when you press  And when you release Two bytes: F0 followed by key scan code Two bytes: F0 followed by key scan code Example: Example:  Space pressed, 29 sent  Space released, F0 29 sent  If you hold key, scan code repeated

11. 11Resources  Information http://www.beyondlogic.org/keyboard/keybrd.htm  Scan codes http://www.barcodeman.com/altek/mule/scandoc.php  My Verilog for keyboard is on the class website

12. 12 My Verilog  Have Verilog for keyboard  Have tested it with the FPGA kit; seems to work fine  To use: You should memory-map the character code register You should memory-map the character code register  give the keyboard a memory address so the CPU can read it using lw instructions Handle presses and releases appropriately in software Handle presses and releases appropriately in software  maybe add another register to indicate that a new character has arrived..??

13. Mice 13

14. Mouse  Very similar interface (clk & data) But: 3 words sent w/ mouse movement or button press But: 3 words sent w/ mouse movement or button press  Read pp 14-15 of Nexys 3 manual pp 14-15 of Nexys 3 manual 14

15. Movement  Movement is relative XS, YS are sign (+ is up/right) XS, YS are sign (+ is up/right) XV, YV are overflow (too fast) XV, YV are overflow (too fast) L, R are buttons L, R are buttons 15

16. Scroll Wheel, etc.  Extensions to original 2 button PS/2 mouse See http://www.computer-engineering.org/ps2mouse/ See http://www.computer-engineering.org/ps2mouse/ http://www.computer-engineering.org/ps2mouse/ 16

17. Joystick (Courtesy Anselmo Lastra)

18. Atari 2600 Joystick (we only have 2-3) 18 http://www.atariarchives.org

19. We Have Sega Joypads (we have 5-6)  Enhanced version with more buttons Has mux Has mux Select pin chooses first or second set of buttons, L/R Select pin chooses first or second set of buttons, L/R 19 http://pinouts.ru/data/genesiscontroller_pinout.shtml

20. Six Button Use  See http://www.cs.cmu.edu/~chuck/infopg/segasix.txt http://www.cs.cmu.edu/~chuck/infopg/segasix.txt http://www.cs.cmu.edu/~chuck/infopg/segasix.txt  Use select to use buttons B & C  To use X, Y, Z, need to pulse select 20

21. NEXYS Mappings (PMOD JA)  We have to connect them using wires… 21 SignalFPGA PinDB-910- Pin UpM1514 DownL1723 LeftL1638 RightK1242 Btn A/BM1469 Start/CL1591 SelectM16710 Ground-85 Power-56 PMOD JA is 10-pin connector nearest VGA connector

22. Suggestion  Create FF for Select Memory map so you can set from CPU Memory map so you can set from CPU  Memory map the input signals I would not latch them I would not latch them  Please power off when plugging or unplugging Sega joypads! Careful when plugging in PCB Careful when plugging in PCB 22

23. 23Links  http://pinouts.ru/data/JoystickAtari2600_pinout.shtml http://pinouts.ru/data/JoystickAtari2600_pinout.shtml  http://pinouts.ru/data/genesiscontroller_pinout.shtml http://pinouts.ru/data/genesiscontroller_pinout.shtml  http://www.epanorama.net/documents/joystick/ataristick.html http://www.epanorama.net/documents/joystick/ataristick.html  http://www.epanorama.net/documents/joystick/tvgames.html http://www.epanorama.net/documents/joystick/tvgames.html  http://www.cs.cmu.edu/~chuck/infopg/segasix.txt http://www.cs.cmu.edu/~chuck/infopg/segasix.txt