Radiation effects can induce, amongst other phenomena, logic errors in digital circuits and systems. These logic errors corrupt the states of the internal memory elements of the circuits and can propagate to the primary outputs, affecting other onboard systems. In order to avoid this, Triple Modular Redundancy is typically used when full robustness against these phenomena is needed. When full triplication of the complete design is not required, selective hardening can be applied to the elements in which a radiation-induced upset is more likely to propagate to the main outputs of the circuit. The present paper describes a new approach for selectively hardening digital electronic circuits by design, which can be applied to digital designs described in the VHDL Hardware Description Language. When the designer changes the datatype of a signal or port to a hardened type, the necessary redundancy is automatically inserted. The automatically hardening features have been compiled into a VHDL package, and have been validated both in simulation and by means of fault injection.

This paper describes the design and implementation of a virtual device to perform simulation-based fault injection campaigns. The virtual device is fully compatible with the same user software that is already being used to perform fault injection campaigns in existing FPGA (Field Programmable Gate Array)-based hardware devices. Multiple instances of the virtual device can be launched in parallel in order to speed-up the fault injection campaigns, without any preexisting limitations on number, such as available license seats, since the virtual device can be compiled with the open-source simulator GHDL. This virtual device also allows one to find bugs in both software and firmware, and to reproduce in simulation, with total visibility of the internal states, corner cases that may have occurred in the real hardware.

The verification of complex digital designs often involves the use of expensive simulators. The present paper proposes an approach to verify a specific family of complex hardware/software systems, whose hardware part, running on an FPGA, communicates with a software counterpart executed on an external processor, such as a user/operator software running on an external PC. The hardware is described in VHDL and the software may be described in any computer language that can be interpreted or compiled into a (Linux) executable file. The presented approach uses open source tools, avoiding expensive license costs and usage restrictions.