AN2262 Motorola / Freescale Semiconductor, AN2262 Datasheet - Page 2

• Manufacturer Part Number: AN2262
• Description: Wireless HC08 Modem
• Manufacturer: Motorola / Freescale Semiconductor

AN2262/D
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The example system (shown in
communicates with the Internet on one side and with numerous embedded
devices (e.g., at home) on the other side.
The main idea on the background is that it’s not necessary to connect all such
small devices directly over IP (Internet protocol). Although well-established and
known, IP has several disadvantages which don’t allow its effective
implementation for low-bandwidth media and/or for devices with very limited
resources (mainly RAM/ROM storage). Also, the overhead during transfer of
small amounts of data is pretty heavy and not suitable for low-bandwidth links.
It is wiser then to implement the gateway between ‘the IP world’ (e.g., the
Internet) and the world of many embedded devices located in one niche (e.g.,
in one household). Besides many more advantages (like centralized security
and central access rights management), simpler protocols and ‘cheaper RF
media’ can be effectively used on the ‘home’ side. The same gateway can also
serve as a central point for Internet access for a home LAN (local area network)
but this is out of the scope of this document.
The low-cost RF technology for unlicensed ISM (industrial, scientific, and
medical) bands enables trouble-free installation and use of home devices that
require only moderate data (both speed and amount). Simple on/off control,
general setup, or basic diagnostics of white goods are typical examples of such
communication. Baud rates of 9600–19200 bps with 100 ms + latency are
usual and quite acceptable for the most of applications of this nature.
Figure 1. Home Interconnectivity System Overview
Wireless HC08 Modem
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