JHDLBits: The Merging of Two Worlds

This paper introduces JHDLBits, the integration of two prominent FPGA design tools: JHDL and JBits. JHDLBits offers the low-level access and control provided by JBits with the high-level structural circuit design of JHDL. Furthermore, the JHDLBits flow provides greater control of resource manipulation, placement, and routing, and gives researchers a “sandbox” to explore advanced interactions with FPGA bitstreams. This paper presents the overall architecture of the open-source JHDLBits project. Details are provided on how the core components – JHDL, JBits3 for Virtex-II, and the ADB connectivity database – are linked together to provide a cohesive design environment.