Design and analysis of high speed low power reusable on chip bus based on wishbone

FPGA and ASIC design based on SoC technology have been widely used in the embedded systems. A flexible interconnection scheme is crucial in SoC design. In this paper, we adopt the Wishbone bus to interconnect a variety of devices due to its open architecture and many a free IP core with a Wishbone interface supplied by Open Cores organization. In general SoC system, a single bus interconnects all devices that are not divided into high-performance unit such as CPU, on-chip ram and low speed devices like uart, gpio and so on. It leads to a big problem: all Wishbone bus cycles run at the speed of the slowest device. We have to add the corresponding logic to regulate the system frequency for some low-speed devices, but it causes a new problem which increases the overall system power consumption. In view of the drawback, based on Wishbone bus, the paper proposes a double bus that makes first level Wishbone bus and the second level bus to interconnect the different devices according to the speed of the devices. Finally, we set up a SoC system to verify the performance of the proposed bus and the result shows that the double bus is feasible in low-power SoC design.