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Mouse/Trackball Interfaces
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| Mouse/Trackball Interfaces From time to time, you might need to check the physical interface on a mouse or trackball. At its core, the mouse uses a simple serial device—that is, it can pass serial data back and forthwith the host computer using communication protocols managed by the mouse driver. Three types of mouse interfaces are common in the field serial mice, bus mice, and PS mice. This part of the chapter highlights the pinouts for each interface type. Serial mice A serial mouse connects to an existing RS serial port at the PC (usually COM or COM) using a standard DB-9F (pin female) or DB-25F (pin female) connector. Table 25-1 lists the pinout fora Logitech Type M, V, or W serial mouse connector. Bus mice In many circumstances, it is not possible to use a serial mouse on an open COM port, and the PC is not fitted with a PS port. In this case, it might be necessary to use a bus mouse which basically involves using a standalone mouse-controller board a bus mouse controller) and a mouse fitted with a bus mouse connector—usually a male sub-miniature “D”-type connector or a miniature male DIN (circular) connector. Be careful not to mistake the pin DIN connector of a bus mouse for the pin circular connector of a PS mouse. Symptoms Symptom 25-1. The mouse cursor appears, but it only moves erratically as the ball moves if at all) 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. You should not have to disassemble your computer during this procedure. Start your investigation by powering down the computer. Check the device’s cable connector at the computer. Be sure that the connector is tight and inserted properly. If you are in the habit of continually plugging and unplugging the mouse/trackball, excessive wear can develop in the connector pins overtime. If the connector does not seem to fit tightly in the computer, try anew pointing device. More likely, the device’s rollers are not turning, or are turning only intermittently. Inmost 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 blowout any dust or debris that might have settled into the mouse/trackball housing. Refer to the preceding section on cleaning and attempt to clean the device thoroughly. Never use harsh solvents or chemicals to clean the housings or ball. If you have the mouse connected to a standard serial communication port (a COM port, you should check that no other devices are using the same interrupt (IRQ). For example, COM and COM use the same IRQ, while COM and COM share another IRQ. If you have a mouse on COM and a modem on COM, there will almost invariably be a hardware conflict. If possible, switch the mouse (or conflicting device) to another port and try the system again. Download 1.89 Mb. Share with your friends:
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