星上SRAM型FPGA抗SEU内部刷新系统设计

Design of SRAM-FPGA Internal Scrubbing System for Anti-SEU on Satellite

卫星上常用的静态随机存储器(SRAM)型现场可编程门阵列(FPGA)器件易受到空间环境中高能粒子辐射发生单粒子翻转,从而可能导致电路出现故障,引起卫星无法正常工作。针对此问题,文章采取的抗单粒子翻转方法是通过FPGA的内部访问接口(ICAP),对配置数据进行回读刷新,并使用纠错能力更强的RM(2,5)码来替代常用的FRAME_ECC纠错码,最高可以支持对3个比特位的翻转进行检错纠错,进一步提高了系统的纠错能力。除此外,还对刷新控制电路部分进行三模冗余加固处理,降低了刷新控制电路出现单粒子翻转的可能性。并且对冗余模块增加错误判断,可及时识别冗余部分是否发生单粒子翻转,避免由于错误累积可能导致多个冗余模块发生故障的现象。通过以上措施的改进,提高了系统的可靠性。同时在布局布线过程中,将待刷新电路与刷新控制电路进行分布式布局,使得对待刷新电路帧地址的确定更加方便。最后,通过实验仿真论证了改进后的内部刷新系统容错率是传统内部刷新系统的2.56倍。

SRAM FPGA devices commonly used on satellites are susceptible to single event upset due to high-energy particle radiation in the space environment,which can cause circuit failures and even satellites failures.In response to this problem,the anti-single-event-flipping method adopted in this paper is to read back and scrub the configuration data through the ICAP interface inside the FPGA,and use the RM(2,5)code with stronger error correction capability to replace the commonly used FRAME_ECC.It supports error detection and correction for 3-bit flipping,which further improves the error correction capability of the system.In addition,three-mode redundancy reinforcement is performed on the scrubber control circuit,which reduces the possibility of single event upset in this circuit.In addition,error judgments are added to the redundant modules,which can identify in time whether the redundant part has a single event upset,and avoid the phenomenon that multiple redundant modules may fail due to the accumulation of errors.Through the improvement of the above measures,the reliability of the system is improved.In the place and route,the circuit to be scrubbed and the scrubber are arranged in a distributed layout,which makes it more convenient to determine the frame address of the circuit to be scrubbed.Finally,through experimental simulation,it is proved that the fault tolerance rate of the improved internal scrubbing system is 2.56 times that of the traditional internal scrubbing system.