基于差值二次分配的扫描链平衡算法

 IP核的测试时间与其加载测试封装后的最大输入/输出扫描链长度有直接关系,为了降低测试成本,减少测试时间,必须对IP核内的扫描链进行平衡设计.最为经典的扫描链平衡方法是BFD(Best Fit Decrease)方法,它具有实现简单、算法复杂度低等优点,但是其分配的结果尚有待提高之处.本文提出一种基于差值的二次分配的扫描链平衡方法,其主要思想是选择IP核内部的某一条扫描链作为基准扫描链,将其长度记为L,将所有长度超过L的扫描链与之做差,并将差值记为di.在第一次分配中,只将长度大于L的扫描链按照长度为L的基准扫描链进行分配;然后将长度小于L的扫描链与差值di重新排序后,按照从大到小的顺序,依次将其放置在可以放置的最小的测试封装扫描链上进行第二次分配.该方法简单易实现,通过在ITC'02 SOC标准测试集上实验,数据表明,基于差值二次分配的扫描链平衡方法与现有方法相比,能得到更好的平衡结果.

Wrapper Scan Chains Balance Algorithm Base on Twice-Assigned Method by the Chains Difference

Test application time of IP is based on the maximum scan in/out chains.A well balance wrapper scan chains design is an important approach to minimize the test application time and test cost.Best Fit Decrease(BFD) is the most classical scan chains balance method,which is easy to realize,but the result is not the best.This paper describes a wrapper scan chains balance algorithm base on twice-assigned method by the chains difference.The main idea of the proposed solution is that select a standard chain,with its length L,find the chains which length longer than L from all internal scan chains of the IP core,compute these chains the difference di with L,regard these chains as L in the first-assigned.Sort the length shorter than L and di in descending order of length,assign to the enable shortest wrapper scan chain in the second-assigned.The proposed method is also easy to use,experimental results for the ITC’02 SOC Test Benchmarks show that the method in this paper can get better balanced result when compared to the existing solutions.