<p>Due to the development towards more dense programmable devices (FPGAs) it is today possible to fit a complete embedded system including microprocessor, bus architecture, memory, and custom peripherals onto one single reprogrammable chip, it is called a System-on-Chip (SoC). The custom peripherals can be of literally any nature from I/O interfaces to Ethernet Media Access Controllers. The latter core, however, usually consumes a big part of a good sized FPGA. The purpose of this thesis is to explore the possibilities of interfacing an FPGA based Microblaze system to an off-chip Ethernet MAC/PHY. A solution which would consume a smaller part of the targeted FPGA, and thus giving room for other on-chip peripherals or enable the use of a smaller sized FPGA. To employ a smaller FPGA is desirable since it would reduce power consumption and device price. This work includes evaluation of different available Ethernet devices, decision of interface technology, implementation of the interface, testing and verification. Since the ISA interface still is a common interface to Ethernet MAC devices a bus bridge is implemented linking the internal On-Chip Peripheral Bus (OPB) with the ISA bus. Due to delivery delays of the selected Ethernet chip a small on-chip ISA peripheral was constructed to provide a tool for the testing and verification of the bus bridge. The main result of this work is an OPB to ISA bus bridge core. The bridge was determined to work according to specification, and with this report at hand the connection of the Ethernet chip to the system should be quite straightforward.</p>

Due to the development towards more dense programmable devices (FPGAs) it is today possible to fit a complete embedded system including microprocessor, bus architecture, memory, and custom peripherals onto one single reprogrammable chip, it is called a System-on-Chip (SoC). The custom peripherals can be of literally any nature from I/O interfaces to Ethernet Media Access Controllers. The latter core, however, usually consumes a big part of a good sized FPGA. The purpose of this thesis is to explore the possibilities of interfacing an FPGA based Microblaze system to an off-chip Ethernet MAC/PHY. A solution which would consume a smaller part of the targeted FPGA, and thus giving room for other on-chip peripherals or enable the use of a smaller sized FPGA. To employ a smaller FPGA is desirable since it would reduce power consumption and device price. This work includes evaluation of different available Ethernet devices, decision of interface technology, implementation of the interface, testing and verification. Since the ISA interface still is a common interface to Ethernet MAC devices a bus bridge is implemented linking the internal On-Chip Peripheral Bus (OPB) with the ISA bus. Due to delivery delays of the selected Ethernet chip a small on-chip ISA peripheral was constructed to provide a tool for the testing and verification of the bus bridge. The main result of this work is an OPB to ISA bus bridge core. The bridge was determined to work according to specification, and with this report at hand the connection of the Ethernet chip to the system should be quite straightforward.

In this exam project the investigation has been done to determine, which profits that can be made by switching an internal bus between two chips, one FPGA and a processor, to an internal bus implemented on only one chip, System on Chip. The work is based on measurements made in real time in Xilinx’s development tools on different buses, AXI4 and AXI4-Light connected to AXI3. The port that is used is FPGA’s own GP-port. Besides measuring the time of transactions also physical aspects have been investigated in this project: space, costs and time. Based on those criteria a comparison to the original construction was made to determine which benefits that can be achieved. The work has shown a number of results that are in comparison with the original construction. The System on Chip has turned out to be a better solution in most cases. When using the AXI4-Light-bus the benefits were not as obvious. Cosmic radiation, temperature or humidity are beyond the scope of this investigation. In the work the hypothetic deductive method has been used to prove that the System on Chip is faster than the original design. In this method three statements must be set up against each other; one statement that ought to be true, one statement that is a contradiction and a conclusion of what is proved. The pre-study pointed out that the System on Chip is a faster solution than the original construction. The method is useful since it proves that the pre-study is comparable to the measured results. / I detta examensarbete har undersökningar gjorts för att fastställa vilka vinster som går att göra genom att byta en internbuss mellan två chip, en FPGA och en processor, mot en intern buss implementerat på ett enda chip, System on Chip. Arbetet bygger på mätningar gjorda i realtid i Xilinx utvecklingsverktyg på olika bussar, AXI4 och AXI4‑Lite som är kopplade internt mot AXI3. Den port som används är FPGAs egen GP‑port. Förutom att mäta överföringshastigheterna, har även fysiska aspekter som utrymme, kostnader och utvecklingstid undersökts. Utifrån dessa kriterier har en jämförelse gjorts med den befintliga konstruktionen för att fastställa vilka vinster som går att uppnå. Arbetet har resulterat i ett antal resultat som är ställda mot de förutsättningar som fanns i den ursprungliga lösningen. I de flesta fall visar resultatet att ett System on Chip är en bättre lösning. De fall som var tveksamma var vid viss typ av överföring med AXI4‑Lite bussen. I arbetet har inte undersökning av kosmisk strålning, temperatur eller luftfuktighet betraktas. I arbetet med att försöka att bevisa att ett System on Chip är snabbare än den ursprungliga uppsättningen har utvecklingsmetoden hypotetisk deduktiv använts. Denna metod bygger på att man från början sätter upp ett påstående, som man förutsätter är sant, följt av en konjunktion, som inte får inträffa, för att slutligen dra en slutsats, som konstaterar fakta. Eftersom fakta som lästes in i början av arbetet pekade på att ett System on Chip var en snabbare och billigare lösning kändes metoden användbar. Under arbetets gång har det visat sig vara en bra metod som också ger ett resultat där sannolikheten för att det är en snabbare lösning ökar. Däremot säger inte metoden att det är helt säkert att den i alla situationer är bättre, vilket kan ändras om man använder andra förutsättningar eller tar med andra aspekter.