FPGA Prototype - Debugging

Debugging

One of the most difficult and time consuming tasks in FPGA prototyping is debugging system designs. Debugging has become more difficult and time consuming with the emergence of large, complex ASICs and SoC designs. To debug an FPGA prototype, probes are added directly to the RTL design to make specific signals available for observation, synthesized and downloaded to the FPGA prototype platform.

A number of standard debugging tools are offered by FPGA vendors including ChipScope and SignalTAP. These tools can probe a maximum of 1024 signals and require extensive LUT and memory resources. For SoC and other designs, efficient debugging often requires concurrent access to 10,000 or more signals. If a bug is not able to be captured by the original set of probes, gaining access to additional signals results in a “go home for the day” situation. This is due to long and complex CAD flows for synthesis and place and route that can require from 8 to 18 hours to complete.

An improved approach is the Certus tool from Tektronix that brings full RTL-level visibility to FPGA-based debugging. It uses a highly efficient multi-stage concentrator as the basis for its observation network to reduce the number of LUTs required per signal to increase the number of signals that can be probed in a given space. The ability to view any combination of signals is unique to Certus and breaks through one of the most critical prototyping bottlenecks.