Specifications

Figure 16. Place of a Device Driver in Linux
Figure 16 shows the place of a device driver in Linux relative to the
device:
 User program or utility: A user program, or utility, makes calls on the
kernel but never directly calls a device driver.
 Kernel: The kernel runs in supervisor mode and does not communicate
with a device except through calls to a device driver.
 Device driver: A device driver communicates with a device by reading
and writing through a bus to peripheral device registers.
 Bus: The bus is the data path between the main processor and the
device controller.
 Controller: A controller is a physical interface for controlling one or
more devices. A controller connects to a bus.
 Peripheral device: A peripheral device is a device that can be connected
to a controller, for example, a disk or tape drive. Other devices (for
example, the network) may be integral to the controller
Many devices were employed in this thesis that include PCM-7130 IO
devices, USB camera, USB flash disk, keypad, RFID module with RS232,
PCMCIA wireless card.; however, the devices need to enable the drivers or
add the new drivers in Linux before using these devices. The devices need to
be enabled in Linux that is discussed in this section, and the installation of
new devices would be discussed as following chapters.
The driver must be setting up first when the devices are used, as shown
Figure 16. In fact, the drivers are the part of kernel, so we need to adjust
some of the kernel option for enabling the drivers.
3-3 Web Server
The web server in PCM-7130 can provide the web base remote monitor, web
based remote management, and some entertainment. The structure of web server
includes a PHP[6] script and MySQL[7] database. The PHP is used to access MySQL
and generals the web pages, and the MySQL can provide a useful database in home,
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