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Simplify IoT connectivity of embedded devices

Posted: 24 Oct 2013 ?? ?Print Version ?Bookmark and Share

Keywords:Internet of Things? TCP/IP? operating system? microcontroller? Ethernet controller?

According to ABI Research, there are more than 10 billion wirelessly connected devices in the market today. By 2020, more than 30 billion devices will be wirelessly connected to the Internet of Things (Internet of Everything).

With so much focus on the Internet of Things, many OEMs find themselves under increasing pressure to introduce Internet connectivity to a wide range of devices that can benefit from being able to communicate with other devices.

However, many developers are unfamiliar with how to implement a robust TCP/IP stack. This article will explore key issues relating to enabling Internet connectivity in embedded systems, as well as discuss how new tools allow developers to introduce TCP/IP to systems without having to work with low-level implementation details.

The TCP/IP protocol
The TCP/IP (Transmission Control Protocol/Internet Protocol) is the common language used to exchange data between hardware devices connected to the Internet. These rules govern the exchange mechanism between the terminal operating system (Windows, iOS, Linux, etc.), and a set of specific protocols, including SMTP, FTP, HTTP, etc.

TCP/IP is subdivided into "layers" (figure). Internet data is routed from the Application layer to the Transport layer in the format of data fragments. The Physical layer is where data is physically moved through "The Internet" under the Ethernet protocol defined by the IEEE 802.3 specification. Ethernet comes in many flavours offering different maximum bit rates, modes of transmission, and transmission media (Fibre, Coax, etc.). The Media Access Control (MAC) is a significant part of the physical layer, and the MAC address represents the physical address of the node(s) on an Ethernet network. Every Ethernet frame contains both a source and destination address.

Figure: Data transmission over the internet.

The Application layer provides the user interface. The following are the common application layer protocols [1] .
???Hyper Text Transfer Protocol (HTTP): Transfer data associated with browsing of the World Wide Web.
???Simple Mail Transfer Protocol (SMTP): Deliver e-mails across the internet
???File Transfer Protocol (FTP): Transfer files over the internet
???Domain Name System (DNS): Translate domain names
???Dynamic Host Configuration Protocol (DHCP): Dynamically assign IP addresses to a particular node
???Telnet: Establish an interactive TCP connection to a node.
???Simple Network Time Protocol (SNTP): Allow nodes to synchronise their clocks to a reference clock.
???Simple Network Management Protocol (SNMP): Used to monitor network attached devices for conditions that require intervention, such as faults, etc.

TCP/IP and the Internet of Things
Two of the most common uses of an embedded TCP/IP stack are for messaging and web page display. For example, a simple SMTP-based messaging system allows a microcontroller to take sensor readings and, at a pre-determined interval, email or message those readings to a centralized repository for logging and analysis.

Such an application in the home might be to email the temperature of the house to residents every hour. Of course, this example can be extended much further. The embedded microcontroller might also monitor whether the doors and windows are locked and the lights are off.

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