Title: Mouse
1Mouse
TTypes of Mouse There are three technologies
available to detect the mouse movement, they
are n Mechanical n
Opto-mechanical n Optical
2Mechanical
- 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
3Opto-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.
4Opto-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.
5Optical
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.
6Pin 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.
7Mouse 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
-
8Trouble 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.
9Trouble 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.
10Trouble 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. -
11Trouble 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.
12Trouble 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 -