A readback based general debugging framework for soft-core processors

Using Field Programmable Gate Arrays (FPGAs) as implementation platform for systems-on-chip (SoC) has become quite popular. Typically, the software part of the system functionality is executed on a soft-core processor. Debugging such systems becomes more difficult than standard SoCs since regular debugging facilities are not always available for the processor cores and also additional hardware problems can overlap with software bugs. Thus, it is interesting to provide a general debugging framework that can help to identify SW and HW problems. In this contribution, we use the readback feature of modern FPGAs to implement such a general framework while at the same time minimizing the additional HW resources required for the debugging. We interface our debugging facilities with a full featured development environment such that the user can work at a very high level of abstraction.