Introduction
Our project was to design an interface that enabled the FPGA board to communicate with other devices via the on-board Ethernet connection following several established networking protocols.
Project Goal
This year's ECE 5760 class used a Terasic DE2-115 board, containing an Altera Cyclone IV FPGA. Also on board are two Marvell 88ee1111 (Ethernet PHY) chips that allow two gigabit Ethernet connections. Unfortunately, the only IP cores that could be found to make use of the Ethernet were closed-source and required the use of Altera’s proprietary NIOS II processor, which is also closed-source. There are many applications and potential projects that can be implemented only with board that has the ability to connect to the Internet-a web server, a sensor that streams data to a server, or a network of several boards for a parallel processing scheme, to name a few. These Ethernet cores would be ideally open-source, very small, and easily configurable.
The Marvell Chips only provide a basic low-level interface to the Ethernet. They perform virtually no flow or error control, and only stream the data as it comes through. We managed to find an open-source (see Licensing) Ethernet Controller, "EthMac", on OpenCores.org that interfaced with the PHY chip and could capture entire Ethernet frames of data easily.
Ideally, we would have liked to connect this Ethernet core to a small, stack-based cpu, but found that for debugging, it was much easier to use an Altera NIOS II processor to manipulate bytes of data. The NIOS processor uses C to program, making math and string operations relatively easy. Additionally, the Altera Monitor provides an easy interface for compiling and communicating with the NIOS.
For our project, we designed a software interface that communicated with the board via the Altera Monitor. Through this interface, the board could receive data packets sent over an Ethernet network from an external source. Additionally, the board was able to transmit data packets of its own. The networking protocols that our interface was able to successfully implement are the ARP, PING (ICMP), and UDP protocols.