As system-on-chip (SoC) integration is growing very rapidly, increased circuit densities in SoC have lead a radical increase in test data volume and reduction of this large test data volume is one of the biggest challenges in the testing industry. This paper presents an efficient test independent compression scheme primarily based on the error correcting Hamming codes. The scheme operates on the pre-computed test data without the need of structural information of the circuit under test and thus it is applicable for IP cores in SoC. Test vectors are equally sliced into the size of ‘<em>n’</em> bits. Individual slices are treated as a Hamming codeword consisting of ‘<em>p’</em> parity bits and ‘<em>d’</em> data bits (<em>n = d + p)</em> and validity of each codeword is verified. If a valid slice is encountered<em>’</em> data bits prefixed by ‘<em>1’</em> are written to the compressed file, while for a non-valid slice all ‘<em>n’</em> bits preceded by ‘<em>0’</em> are written to the compressed file. Finally, we apply Huffman coding and RLE in order to improve the compression ratio further The efficiency of the proposed hybrid scheme is verified with the experimental outcomes and comparisons to existing compression methods suitable for testing of IP cores.
Multilevel Huffman Coding: An Efficient Test-Data Compression Method for IP Cores