Mitigation Approaches - 4.1 English

Soft Error Mitigation Controller Product Guide (PG036)

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4.1 English

Soft error mitigation for design state in Block Memory, Distributed Memory, and Flip-Flops can be performed in the design itself, by applying standard techniques such as error detection and correction codes or redundancy. Soft errors in unused design state resources (those physically present in the device, but unused by the design) are ignored. Designers concerned about reliability must assess risk areas in the design and incorporate mitigation techniques for the design state as warranted.

Soft error mitigation for the design function in Configuration Memory is performed using error detection and correction codes.

Configuration Memory is organized as an array of frames, much like a wide static RAM. In many device families, each frame is protected by ECC, with the entire array of frames protected by CRC in all device families. The two techniques are complementary; CRC is incredibly robust for error detection, while ECC provides high resolution of error location.

The SEM Controller builds upon the robust capability of the integrated logic by adding optional capability to classify Configuration Memory errors as either “essential” or “non-essential.” This leverages the fact that only a fraction of the Configuration Memory bits are essential to the proper operation of any specific design.

Without error classification, all Configuration Memory errors must be considered “essential.” With error classification, most errors will be assessed “non-essential” which eliminates false alarms and reduces the frequency of errors that require a potentially disruptive system-level mitigation response.

Additionally, the SEM Controller extends the built-in correction capability to accelerate error detection and provides the optional capability to handle multi-bit errors.

If the features offered by the SEM Controller are not required, the integrated soft error detection and correction capability in the silicon should be sufficient for SEU mitigation. See the 7 Series FPGAs Configuration User Guide (UG470) [Ref 1] for information on how to use the built-in error detection and correction capability for 7 series FPGAs and Zynq®-7000 SoCs.