Dangling-wire avoidance routing for crossbar switch structured ASIC design style

In the routing architecture of a structured ASIC, crossbar is one of the most area efficient switch blocks. Nevertheless, dangling-wire occurs when there is a routing bend in crossbar switch. The dangling-wire incurs longer wire length as well as higher interconnection capacitance. In this paper, we are motivated to tackle dangling-wire routing issues for structured ASIC. We first propose a compact graph model for crossbar switch routing. With our graph model, switch connectivity relations can be removed to keep the 2-D structured ASIC routing graph efficient and to speed up run-time of our routing algorithm. Furthermore, we leverage state-of-the-art techniques into our routing framework, which contains deferred pin assignment, Steiner point re-assignment, and anchor pair insertion, to minimize dangling-wires taking both total wire length and routing congestion into account. The experimental results demonstrate that our proposed routing framework greatly reduces 21% dangling-wires, 34% channel width, and 13% total wire length as compared with VPR using crossbar switch.