SOC技术的迅速发展,使得芯片测试技术面临重大的挑战,为了降低测试成本、减小测试时间,IP核扫描链平衡设计尤为重要。提出基于"基准量+裕量"拆分重组的扫描链平衡算法,选取一基准块作为标尺的基本单位,并对各内扫描链长度进行测量,拆分内扫描链的基准量和裕量,再通过"近似封装、重组"两阶段优化确定IP核的封装结果。主要思想可分为4步:首先结合内扫描链的长度(记为L),计算出合适的扫描链基准块(记为L_Block),作为标尺基本单位;其次利用基准块衡量各内扫描链长度L,得到基准量(记为L'),并计算L'与L的裕量(记为ΔL),再依据基准量的大小对L'及ΔL进行归类,此过程称为"拆分";然后将L'按自大至小的顺序分配至当前最短的封装扫描链中,确定扫描链基本封装结构,此过程称为"近似封装";最后将ΔL按照分配灵活度及平衡度升序的顺序与L'重组内扫描链,负裕量重组至当前最长封装扫描链中,正裕量重组至当前最短封装扫描链中,此过程称为"重组",最终得到封装结果。该方法通过对ITC’02 SOC标准测试集进行实验,得到更平衡的分配结果。
With the rapid development of SOC technology,chip testing faces significant challenges. In order to decrease testing cost and application time,IP core wrapper scan chain balance design is particularly important. The scan chain balance algorithm based on separation and recombination of integer-float portions is proposed,and a datum blocks is selected as the basic units of ruler. The length of scan chain is measured to get integer-float portions,and the result of the IP core wrapper is separated through approximate wrapper and recombination.The main idea includes 4 steps. Firstly,combined with the length of the scan chain( L),an appropriate datum blocks is calcualted as the basic units of ruler. Secondly,the datum blocks is used to measure the scan chain length and achieve integer portions( L') and allowance( ΔL) of L' and L,classifying L' and ΔL by the value of integer portions,and this process is called separation. Thirdly,to achieve the basic structure of wrapper scan chains,we assign L' to the current shortest scan chain in descending order,and this process is called approximate wrapper. Finally,according to the balance degree and flexibility,ΔL is recombined with L' to achieve scan chains in ascending order,negative ΔL with current shortest scan chain,positive ΔL with current longest scan chain,and this process is called recombination. Experiment results for the embedded core from the ITC'02 SOC Test Benchmarks show that the algorithm achieves more balanced allocation.