Networking for All Devices Great and Small
Incorporating networking support in an embedded device might seem like a daunting task at first glance. However, even an older embedded system can be updated with a software network stack to extend its feature set and incorporate modern conveniences such as emailing an administrator when alarms occur, and a web server to provide a remote user interface accessible from any web browser.
Certainly, there are costs to including a network stack. The network interface (such as Ethernet) can quickly become expensive and complicated. You may need extra hardware (with additional costs for chips and connectors, board space, and power consumption) and software (with new drivers). However, this does not have to be the case. You could run a simple Serial Line Interface Protocol (SLIP) or Point to Point Protocol (PPP) over a UART port for the network interface. Most embedded processors include at least one UART, and SLIP and PPP are very basic protocols to implement—no more difficult than the Monitor and Control program we looked at in Chapter 9.
The demands of a network stack may cause you to worry that too many system resources are required. The processing power and memory needed to accommodate network support can be greatly reduced by choosing the proper network stack. Several software network stacks that are targeted at embedded systems, where processor cycles and memory are limited, are currently available in the open source community.
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