Debug methods for hybrid CPU/FPGA systems

The combining of one or more CPU's and an FPGA fabric on the same die is growing in popularity. Such programmable system-on-chip (PSOC) systems promise performance and development time advantages over conventional technology. In a PSOC design, design errors may occur in many different places - the design of the CPU, the embedded software, the FPGA-based parts of the design, or the interfaces between these various parts. This paper presents a flexible tool that allows the user to dynamically adapt the CAD tool's behavior to the level of detail needed to track down design errors in PSOC designs. It provides for the creation of and coexistence of software source debuggers and gate level debug tools, all incorporated into the same debugging environment. A prototype PSOC debugging system based on a derivative of the JHDL CAD tool is presented which illustrates the range of debug support in both simulation and hardware execution modes that can be provided for PSOC debug. Extensions to the tool to support a wider range of embedded processors and GNU compiler tools are discussed along with conclusions and future work.