| Based on HTTP, IPP (Internet Printing Protocol) acts as an application layer protocol. The latest version 1.1 of IPP was issued by IETF in 2000. End users' printing tasks can be distributed and managed over the Internet. In this paper, the fundament of IPP is studied, and the embedded hardware and software for IPP are constructed as well. Meanwhile, the essential function of IPP is tested.The experimental work is divided into two parts: hardware design and software design.The ATmega128 chip containing the AVR core is extended with interfaces to the LAN91C111 Ethernet chip and SPP (Standard Parallel Port). As for the software, free Nut/OS is chosen to multitask complex programmes. TCP/IP stack of Nut/net is analyzed and its API of Socket is used to implement the IPP server. Six required operations of IPP are adopted and tested. Furthermore, the network security risks of IPP are analyzed and estimated, and some suggestions on the security risks are put forward.On the basis of constrained hardware and software, the procedure to achieve IPP server is described. The resolved problems mainly include the following cases: (1)The hardware interface and its driver are designed; (2) the kernel of Nut/OS from BSP (Board Support Package) is extracted ;(3) the TCP/IP stack from Nut/net is customized and a scheme of IPP is implemented. Experiments not only show the proposed scheme is realizable, but also provide a new method for the design of the universal embedded network printing module. |
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