Instrumenting Bitstreams for Debugging FPGA Circuits

Since FPGAs are frequently used to improve the time to market for products, shortening the time for validating and debugging FPGA designs is, thus, important. Our paper discusses how directly instrumenting FPGA programming data, or bitstreams, with debugging hardware can improve the debugging productivity for designers and, thus, reduce a design’s time to market. We also provide some background relating to the current state of the art in debugging FPGA designs and describe how bitstream instrumentation can be automated using JHDL, JBits and JRoute. When instrumenting designs with embedded logic analyzers at the bitstream level, we have witnessed design modification speed-ups ranging from about 6 to 19 times over more conventional techniques. We will also briefly mention other applications of bitstream modification in debugging FPGA designs.