ATEVK1110A

AVR32817: Getting Started with the 32-bit AVR UC3 Software Framework lwIP TCP/IP Stack Features TCP/IP suite description 32-bit 32-bit AVR UC3 lwIP port source file architecture Web, TFTP, SMTP servers: Microcontrollers Network configuration DHCP protocol Application Note 1 Introduction This document describes the software modules of the Atmel 32-bit AVR UC3 Software Framework dedicated to the lwIP TCP/IP stack and illustrates how to get started with the lwIP TCP/IP software in the Software Framework. This document is written for the software developers in order to ease the development of lwIP TCP/IP applications for the 32-bit AVR UC3 series. It assumes that readers are familiar with the 32-bit AVR UC3 series. 2 Overview Lightweight TCP/IP stack designed for embedded systems. The focus of the lwIP TCP/IP implementation is to reduce resource usage while still having a full scale TCP (cf. 3 TCP/IP suite The TCP/IP protocol suite allows systems of all sizes, running different operating systems, to communicate with each other. It forms the basis for what is called the worldwide Internet, a Wide Area Network (WAN) of several million computers. 3.1 TCP/IP Suite Layers The TCP/IP protocol suite is a combination of different protocols at various layers. TCP/IP is normally considered to be a 4-layer system as shown in Figure 3-1. Figure 3-1. Four Layers of TCP/IP Protocol Suite 3.1.1 Application Layer The Application layer handles the details of a particular application. Common TCP/IP Applications include: Telnet for remote login Browser support for displaying web pages File transfer applications E-mail applications Refer to standard network services as well as communication methods used by various application programs. 3.1.2 Transport Layer TCP is responsible for a reliable flow of data between two hosts. Typically, TCP divides data passed to it from the application into appropriately sized chunks for the network layer below, acknowledging received packets that are sent and retransmits lost packets. Since this reliable, flow of data is provided by the Transport Layer, the Application Layer above can ignore these details. UDP is a much simpler service to the Application Layer. It sends packets of data called datagrams from one host to the other, but with no guarantee that the datagrams reach the other end. Desired reliability must be added by the Application Layer. 3.1.3 Network Layer This layer is sometimes called the Internet Layer. It handles the movements of packets around the network. Routing of packets, for example, takes place here. IP (Internet Protocol) and ICMP (Internet Control Message Protocol) provides the Network Layer in the TCP/IP Protocol Suite. 2 AVR32817 32147A - AVR32-06/10