Other circuits control the
home??™s heating, cooling, lighting, audio and video systems, and alarms. When
the data (or a lack of data) indicates a problem, the system generates an alarm.
In each of the examples above, one computer typically acts as a primary computer
that controls a series of secondary computers. A secondary computer
transmits only after the primary computer contacts it and gives it permission.
Some networks have no primary computer. Instead, each computer has equal
status with the others, and each can request actions from the others. For example,
each computer might transmit in a defined sequence. Or on receiving a
message, a computer might have permission to select any other computer to
transmit to.
! "
Many common peripheral functions are available as modules with serial interfaces.
These modules make it easy to add a function to a design. For example,
LCD modules with serial interfaces are available from Scott Edwards Electronics
(www.seetron.com). The USBwiz from GHI Electronics (www.ghielectronics.
com) contains a USB host controller and makes it possible to access USB
devices via an asynchronous serial port. Motor controllers with serial interfaces
are also available from a variety of sources.
Chapter 1
10
These are just a few examples. This book will guide you in choosing components
and writing programs for whatever serial-port application you have in
mind.
Pages:
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33