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Mouse

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Mouse TTypes of Mouse There are three technologies available to detect the mouse movement, they are: n Mechanical n Opto-mechanical – PowerPoint PPT presentation

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Title: Mouse


1
Mouse
TTypes of Mouse   There are three technologies
available to detect the mouse movement, they
are   n      Mechanical n     
Opto-mechanical n      Optical
2
Mechanical
  • Mechanical This mouse has rollers inside and
    when the mouse is moved the rubber ball
    protruding from the underside of the mouse starts
    to rotate in the direction of the movement. As
    the ball rotates it touches and turns two rollers
    mounted at 90-degree angle to each other. One
    roller is used for back-and-forth (vertical
    movement of mouse) movement and the other roller
    is used for left-right movement (horizontal
    movement of mouse) Each roller is attached to an
    encoder which is like a wheel. As the rollers
    turn, these encoders rotate with them. Two pairs
    of contact bars touch the small metal contact
    points provided on the rims of each of these
    encoders

3
Opto-Mechanical Sensors
  • Opto-Mechanical Sensors
  • The next generation of mouse designs replaced the
    mechanical contacts with an optoisolator
    arrangement (Fig. 8). A hard rubber mouse ball
    still rests against two perpendicularly opposed
    metal actuator rollers, but instead of each
    roller driving an array of contacts, the rollers
    rotate slotted wheels, which are inserted into
    optoisolators. An optoisolator shines LED light
    across an air gap where it is detected by a
    photodiode or phototransistor. When a roller (and
    slotted wheel) spins, the light path between LED
    and detector is alternated or chopped. This
    causes the detectors output signal to oscillate
    thus, pulses are generated. The pulse frequency
    is dependent upon mouse speed. As with the
    mechanical mouse, the opto-mechanical mouse
    produces both positive and negative serial
    pulses, depending on the direction of mouse
    movement.

4
Opto-Mechanical Sensors
The opto-mechanical mouse is a great improvement
over the plain mechanical approach. By
eliminating mechanical contacts, wear and tear on
the mouse is significantly reduced, resulting in
much longer life and higher reliability. However,
the mouse is still subject to the interference of
dust and other foreign matter that invariably
finds its way into the mouse housing. Regular
cleaning and internal dusting can prevent or
correct instances of cursor skip or stall. Most
mouse models use opto-mechanical sensors.
5
Optical
Optical In this type of mouse, instead of the
ball and rollers, a light source and
photo-detector is used with a special mouse
pad.   When the mouse is moved on the special
pad, light from the light source gets reflected
from the pad and the photo-detectors inside the
mouse detect horizontal and vertical movements
based on the reflected light received. One of
these photo-detectors is used to detect
back-and-forth (vertical movement of mouse)
movement and the other is used for left-right
movement (horizontal movement of mouse).   In
all the above technologies, the depressing of the
mouse buttons produces a signal, which is sent to
the serial port. Depending upon the button and
the number of times the button is pressed, the
software does the task desired by the user.  
6
Pin configuration of serial (Mouse) port
Mouse connection A mouse can be connected to the
PC in three ways.   Serial port This is the most
common method of connecting the mouse. One end of
the mouse cord has a nine pin female D-shell
connector that is plugged to the serial port
available at the back of the PC (normally
COM1).   Bus In this type of connection, a
special mouse adapter board is installed in the
PC and the mouse is connected to the adapter.
However, this type of connection uses one slot
and so this method is the least used.   Mouse
port In this type of connection, the mouse
control circuitry is built-in on the motherboard
itself, so there is no wastage of one slot as in
the case of the bus mouse.   Wireless This type
of connection does not use a cable to connect the
mouse to the PC. Instead infrared rays or radio
waves are used to transmit signals from the mouse
to the PC and vice-versa.
7
Mouse driver
  • Mouse driver 
  • The mouse device driver already running in the
    computer (most systems load the mouses device
    driver, such as Microsofts MOUSE.COM, during
    computer initialization) interprets the pulses
    generated by the mouse and translates them into X
  •  

8
Trouble shooting
  • The mouse cursor appears, but it only moves
    erratically as the ball moves (if at all)
  • Cable Connector This symptom might occur in
    either the horizontal or vertical axis. This
    symptom suggests that an intermittent condition
    is occurring somewhere in the pointing device.
    Check the devices cable connector at the
    computer. Be sure that the connector is tight and
    inserted properly. If the connector does not seem
    to fit tightly in the computer, try a new
    pointing device.
  •  
  • Dirt More likely, the devices rollers are not
    turning, or are turning only intermittently. In
    most cases, roller stall is caused by a dirty or
    damaged ball, or an accumulation of dirt blocking
    one or both sensors. Clean the ball and blow out
    any dust or debris that might have settled into
    the mouse/trackball housing. Never use harsh
    solvents or chemicals to clean the housings or
    ball.

9
Trouble shooting
  • IRQ Conflict If one has the mouse connected to a
    standard serial communication port (a COM port),
    one should check that no other devices are using
    the same interrupt (IRQ). For example, COM1 and
    COM3 use the same IRQ, while COM2 and COM4 share
    another IRQ. If one has a mouse on COM1 and a
    modem on COM3, there will almost invariably be a
    hardware conflict. If possible, switch the mouse
    (or conflicting device) to another port and try
    the system again.
  •  
  • Continuity If no hardware conflict occurs, and
    cleaning does not correct an intermittent
    condition, remove the devices upper housing to
    expose the PC board and use the multimeter to
    check continuity across each wire in the
    connecting cable. If one cannot find continuity
    or repair faulty wiring, simply replace the
    pointing device.

10
Trouble shooting
  • One or both buttons function erratically (if at
    all)
  • Clean and Check Continuity Buttons are
    prone to problems from dust accumulation and
    general contact corrosion. The first step should
    be power down the computer and disconnect the
    pointing device. Remove the ball and upper
    housing to expose the PC board and switches.
    Spray a small amount of electronics-grade contact
    cleaner into each switch, then work each switch
    to circulate the cleaner. If cleaning does not
    improve intermittent switch contacts, one might
    wish to check continuity across the connecting
    cable.
  •  
  • The screen cursor appears on the display,
    but it does not move Isolating the fault If the
    cursor appears, the device driver has loaded
    correctly and the application program is
    communicating with the driver. The first step
    should be to suspect the serial connection. If
    there is no serial connection, however, no pulses
    will modify the cursors position. If the device
    is attached correctly to its proper serial port,
    the problem probably exists in the pointing
    devices wiring.
  •  

11
Trouble shooting
  • Continuity Remove the ball and upper housing to
    expose the PC board, then use the multimeter to
    check continuity across each wire in the
    connecting cable. Repair any intermittent or open
    wiring if one can, or simply replace the pointing
    device. 
  • The mouse/trackball device driver fails to
    load
  • Device Driver The device driver is a short
    program that allows an application program to
    access information from a pointing device. Most
    computer users prefer to load their device
    drivers during system initialization by invoking
    the drivers in the CONFIG.SYS or AUTOEXEC.BAT
    files.
  • Improper Connection and Re-Initialization If the
    device driver fails to load during
    initialization, the pointing device might not
    have been detected. Ensure the device is securely
    plugged into the proper serial port (or other
    mouse port). If the device is missing or
    incorrectly inserted, install or re-secure the
    pointing device and allow the system to
    re-initialize.

12
Trouble shooting
  • Improper path or Corrupted Driver If one
    sees a File not found error message displayed
    at the point the device driver was supposed to
    load, the driver might have been accidentally
    erased, might be corrupted, or might be located
    in a sub-directory where the CONFIG.SYS or
    AUTOEXEC.BAT files are not looking. Try
    re-installing a valid copy of the mouse device
    driver and ensure that the driver is located
    where the calling batch file can access it.
    Reboot the system.  
  • No Detection and Error Most well-designed
    application programs check for the presence of a
    pointing device through the device driver during
    initial program execution. If the application
    program aborts or fails to execute because of a
    No mouse found or No mouse driver error,
    return to the preceding paragraphs and recheck
    the device and driver installation. 
  • One sees a General protection fault after
    installing a new mouse and driver under Windows
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