Microcontroller Compiler-Assisted Software Fault Tolerance

Commercial off-the-shelf microcontrollers can be useful for noncritical processing on spaceborne platforms. These microprocessors can be inexpensive and consume small amounts of power. However, the software running on these processors is vulnerable to radiation upsets. In this paper, we present a fully automated, configurable, software-based tool to increase the reliability of microprocessors in high-radiation environments. This tool consists of a set of open-source LLVM compiler passes to automatically implement software-based mitigation techniques. We duplicate or triplicate computations and insert voting mechanisms into software during the compilation process, allowing for runtime error correction. While the techniques we implement are not novel, previous work has typically been closed source, processor architecture dependent, not automated, and not tested in real high-radiation environments. In contrast, the compiler passes presented in this paper are publicly available, highly customizable, and are platform independent and language independent. We have tested our modified software using both fault injection and through neutron beam radiation on a Texas Instruments MSP430 microcontroller. When tested by a neutron beam, we were able to decrease the cross section of programs by 17-29x, increasing mean-work-to-failure by 4-7x.