基于MCU的嵌入式設計預算以太網

　　嵌入式設備的連接是一個必須具備的，因為我們進入一個普遍的物聯網（物聯網）世界。無線連接似乎是主要的趨勢，但大多數無線設備最終需要找到一個有線互聯網連接，增加帶寬和可靠性。我們的好朋友，傳統的有線以太網連接還是需要的樞紐，聚合、橋、存儲和應用服務器的嵌入式節點。低成本的傳感器也可以使用有線以太網，而不是無線解決方案時，成本，帶寬，方便性或可靠性的問題排除了無線方法。幸運的是，許多低成本單片機的家庭現在提供有線以太網支持傳感器，廉價的橋梁和連接聚合可沒有“破”預算銀行。

　　本文將提供廉價的MCU，支持有線以太網連接類型的概述。一些常見的嵌入式應用程序，將需要有線連接的例子將演示如何關鍵MCU的功能和功能相匹配的重要應用需求。

　　Ethernet connectivity in the embedded world

　　Ethernet is such a pervasive element in embedded systems we usually do not give it much thought -- it’s just the “ether” over which computers communicate. Since its initial standardization in 1985 Ethernet has grown and evolved from the original 3 Mbit/s data transfer rate to 100 Gbit/s and has spawned a variety of different media and connection topologies. The flexibility of the multi-layer OSI model and the underlying message structure supported the evolution and optimization that has allowed Ethernet to survive and prosper over several decades.

　　Embedded devices use Ethernet connectivity to send and receive data and control information. More advanced embedded systems can use Ethernet to transmit and receive code updates to add new features and to fix bugs or security weaknesses that can be exploited by hackers to steal confidential information. These updates must be protected from security exploits， or hackers can use the update facility to fully compromise the system and use it as an entry point to attack other portions of the network. Even low-cost embedded systems may make use of the convenience of remote updates， so some level of security must be considered even when the design is done “on a budget.”