AN 866: Mitigating and Debugging Single Event Upsets in Intel® Quartus® Prime Standard Edition

ID 683869
Date 9/28/2021
Document Table of Contents

1.5.1. Planning for SEU Recovery

Reconfiguring a running FPGA typically has a significant system impact. When planning for SEU recovery, you must account for the time required to bring the FPGA to a state consistent with the current state of the system. For example, an internal state machine that is in an illegal state may require reset. Also, the surrounding logic may need to account for this unexpected operation.

Often, an SEU impacts CRAM bits that the implemented design does not use (for example, CRAM bits that control unused logic and routing wires). Depending on the implementation, FPGAs with high utilization only use about 40% of available CRAM bits. Therefore, only 40% of potential SEU events in the entire FPGA require intervention, and you can ignore the remaining 60%. Designs that do not completely fill the FPGA use even fewer available CRAM bits.

You can determine which portions of the implemented design are not critical to the FPGA's function. Examples include test circuitry that is not important to the FPGA operation, or other non-critical functions that the system can log but does not need to reprogram or reset.

Figure 3. Sensitivity Processing Flow