Study and implementation of SpaceWire network redundancy technology based on FPGA

Abstract

In order to improve the reliability of SpaceWire Bus, this paper makes a study of SpaceWire redundancy. In a spacecraft where SpaceWire is used, Redundancy is an important fault-tolerant technology to improve the reliability of the system. However, the regulation of redundancy does not be involved in the current standard of SpaceWire, so, it is necessary to study redundancy technology of SpaceWire. In this paper, without changing SpaceWire bus protocol, SpaceWire bus node with redundant functions is designed and redundant switching function is achieved on the node boards, routers and backbone links. IP logic of SpaceWire node is implemented in the FPGA. The scheme presents an Auto-Protection-Switch (APS) module which makes two independent SpaceWire nodes linked as mutual backup to achieve standby redundant switched function of SpaceWire bus. Redundancy switching process is as follows: APS continuously detects the working state of two mutual backup SpaceWire nodes in one board. When the Loss of Signal for Node A (LOS-A) is detected, APS uses Remote Defect Indicator forNode B (RDI-B) to send switching request code to the remote end through the altemate link. After receiving the switchover request data code, spare receiver module in the remote end generates switching signal to APS module at the same board and APS module immediately switches to the standby SpaceWire bus. At the same time, the confirming data is send to the local standby node. Then, local APS switches to the standby SpaceWire bus. Test results show that the switch time is 33us under the conditions of 200MHz transmission rate.