1. Principles of Computers 9th Lecture
Pavel Ježek, Ph.D.

2. Inside RS-232 Ball & Wheel Mouse

3. Inside RS-232 Ball & Wheel Mouse (higher contrast for lecture)

4. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

5. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1 1
sensor 2 current value
sensor 2 value history

6. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
1 1
sensor 2 current value
sensor 2 value history

7. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
1 1 1
sensor 2 current value
sensor 2 value history

8. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

9. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

10. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history
sensor 2 current value
sensor 2 value history

11. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history
sensor 2 current value
sensor 2 value history

12. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history
sensor 2 current value
sensor 2 value history

13. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

14. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

15. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

16. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

17. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

18. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

19. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

20. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

21. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

22. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history 1
sensor 2 current value
sensor 2 value history

23. Opto-mechanical Axis Sensors
sensor 1 current value
sensor 1 value history
sensor 2 current value
sensor 2 value history

24. ball & wheel mouse logic registers (packet data)
RS-232 Mouse Structure
RS-232
data out
RS-232 bus interface
X axis
Y axis
ball & wheel mouse logic
“magic”
done via wiring
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
Right Button
Left Button

25. RS-232 Mouse Firmware – Using GPIO Registers
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
RS-232
data out
RS-232 bus interface
X axis
Y axis
ball & wheel mouse logic
“magic”
done via wiring
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button

26. RS-232 Mouse Firmware – Two Distinct Algorithms
GPIO(2)
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
data (bit) transmit
algorithm
(B)
RS-232
data out
RS-232 bus interface
X axis
Y axis
ball & wheel mouse logic
gathering (measuring) input changes
& calculating deltas
algorithm (A)
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button

27. gathering (measuring) input changes & calculating deltas algorithm (A)
RS-232 Mouse Firmware – Implementing Algorithm B (Specific for RS-232 Bus, BUT NOT Specific for Ball Mouse – Would Work for Optical Mouse As Well)
GPIO(2)
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
RS-232
data out
RS-232 bus interface
byteId
bitId
X axis
Y axis
ball & wheel mouse logic
gathering (measuring) input changes
& calculating deltas
algorithm (A)
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button

28. ball & wheel mouse logic registers (packet data)
Ball Mouse Firmware – Implementing Algorithm A (part 2) (IS NOT RS-232 Specific!)
GPIO(2)
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
data (bit) transmit
algorithm
(B)
RS-232
data out
RS-232 bus interface
X axis
Y axis
ball & wheel mouse logic
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
current change data x y w
buttons
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button

29. ball & wheel mouse logic registers (packet data)
Ball Mouse Firmware – Implementing Algorithm A (parts 1 & 2) (IS NOT RS-232 Specific!)
GPIO(2)
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
data (bit) transmit
algorithm
(B)
RS-232
data out
RS-232 bus interface
X axis
Y axis
ball & wheel mouse logic
oldX
oldY
oldW
newX
newY
newW
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
current change data x y w
buttons
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button
prevPacketButtons

30. RS-232 Mouse Firmware Structure (All Together)
GPIO(2)
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
RS-232
data out
RS-232 bus interface
byteId
bitId
X axis
Y axis
ball & wheel mouse logic
oldX
oldY
oldW
newX
newY
newW
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
current change data x y w
buttons
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button
prevPacketButtons

31. RS-232 Mouse Firmware Algorithms
GPIO(2)
DATA OUT
GPIO(0)
X sensor 1
X sensor 2
Y sensor 1
Y sensor 2
W sensor 1
W sensor 2
data (bit) transmit
algorithm
RS-232
data out
RS-232 bus interface
byteId
bitId
X axis
Y axis
ball & wheel mouse logic
oldX
oldY
oldW
newX
newY
newW
gathering (measuring) input changes
& calculating deltas
algorithm
registers (packet data)
byte1
byte2
byte3
byte4
wheel
Middle Button
current change data x y w
buttons
GPIO(1)
Middle Btn
Right Btn
Left Btn
Right Button
Left Button
prevPacketButtons

32. History
UNIVAC
(1951)

33. History
UNIVAC
(1951)
Altair 8800
(1974)
Intel 8080

34. History UNIVAC (1951) Altair 8800 (1974) Intel 8080 Apple I (1976)
MOS 6502

35. History UNIVAC (1951) Altair 8800 (1974) Intel 8080 Apple I (1976)
Apple II
(1977)
MOS 6502

36. History UNIVAC (1951) Altair 8800 (1974) Intel 8080 Apple I (1976)
Apple II
(1977)
MOS 6502
MOS 6502
Atari 2600
(1977)
Atari 800
(1979)

37. History UNIVAC (1951) Altair 8800 (1974) Intel 8080 Apple I (1976)
Apple II
(1977)
MOS 6502
MOS 6502
Atari 2600
(1977)
Atari 800
(1979)
Atari 800XE
(1985)

38. History UNIVAC (1951) Altair 8800 (1974) Commodore 6502 ZX Spectrum
Zilog Z80
Intel 8080
Tesla PMD 85
8080
Apple I
(1976)
Apple II
(1977)
MOS 6502
MOS 6502
Atari 2600
(1977)
Atari 800
(1979)
Atari 800XE
(1985)

39. History UNIVAC (1951) Altair 8800 (1974) Commodore 6502 ZX Spectrum
Zilog Z80
Intel 8080
Tesla PMD 85
8080
Apple I
(1976)
Apple II
(1977)
MOS 6502
MOS 6502
Atari 2600
(1977)
Atari 800
(1979)
Atari 800XE
(1985)
IBM PC
(1981)
Intel 8088

40. History UNIVAC (1951) Altair 8800 (1974) Commodore 6502 ZX Spectrum
Zilog Z80
Intel 8080
Tesla PMD 85
8080
Apple I
(1976)
Apple II
(1977)
MOS 6502
MOS 6502
Atari 2600
(1977)
Atari 800
(1979)
Atari 800XE
(1985)
IBM PC
(1981) PC
2015
Intel 8088
Intel i3/i5/i7