AN EFFICIENT ALGORITHM FOR WRAPPER AND TAM CO-OPTIMIZATION TO REDUCE TEST APPLICATION TIME IN CORE BASED SOC

http://www.iaeme.com/IJECET/index.asp 9 editor@iaeme.com
International Journal of Electronics and Communication Engineering & Technology
(IJECET)
Volume 7, Issue 2, March-April 2016, pp. 09-17, Article ID: IJECET_07_02_002
Available online at
http://www.iaeme.com/IJECET/issues.asp?JType=IJECET&VType=7&IType=2
Journal Impact Factor (2016): 8.2691 (Calculated by GISI) www.jifactor.com
ISSN Print: 0976-6464 and ISSN Online: 0976-6472
© IAEME Publication
AN EFFICIENT ALGORITHM FOR
WRAPPER AND TAM CO-OPTIMIZATION
TO REDUCE TEST APPLICATION TIME IN
CORE BASED SOC
Harikrishna Parmar
ECC Department, Nirma University
Ahmedabad, India
Dr.Usha Mehta
ECC Department, Nirma University
Ahmedabad, India
ABSTRACT
System-on-Chip (SOC) designs composed of many embedded cores are
ubiquitous in today’s integrated circuits. Each of these cores requires to be
tested separately after manufacturing of the SoC. That’s why, modular testing
is adopted for core-based SoCs, as it promotes test reuse and permits the
cores to be tested without comprehensive knowledge about their internal
structural details. Such modular testing triggers the need of a special test
access mechanism (TAM) to build communication between core I/Os and
TAM and promises to minimize overall test time. In this paper, various issues
are analyzed to optimize the Wrapper and TAM, which comprises the optimal
partitioning of TAM width, assignment of cores to partitioned TAM width etc.
Key words: TAM; SOC; Core Assignment; Test Bus Architecture, Test
Wrapper
Cite this Article: Harikrishna Parmar and Dr.Usha Mehta. An Efficient
Algorithm For Wrapper and Tam Co-Optimization To Reduce Test
Application Time In Core Based SOC. International Journal of Electronics
and Communication Engineering & Technology, 7(2), 2016, pp. 09-17.
http://www.iaeme.com/IJECET/issues.asp?JType=IJECET&VType=7&IType=2
1. INTRODUCTION
A conceptual modular testing is presented in [1], which includes three structural
elements. 1. Test pattern source, 2. Sink and 3. The TAM and the test wrapper. Now a
day, In large SoC, embedded cores are commonplace. Since embedded cores are not
straight away approachable through chip’s inputs and outputs, the special TAM is

Harikrishna Parmar and Dr.Usha Mehta
needed to test the core at the system level [1] [2]. TAM establishes communication
between the cores and chip input-output and does the job of transferring test data from
chip input-output to the core and vice versa. Test wrapper establishes an interface
between the core and its environment. TAM is essential for modular testing, because
it instantly influences testing time of SoC. The present IEEE 1500 standard describes
wrapper design only and leaves optimization of TAM to the system designer.
Therefore, optimization of TAM is a functional area of research.
A number of TAM architectures, which are working on different heuristics and
algorithm, are proposed in [3]-[18]. The main motto of all these TAM architecture is
to reduce testing time of SoC.
Here, in this paper, an improved TAM is presented for the test bus architecture to
get optimal testing time of SoC.
The whole paper is organized as follows. Section II discusses the prior work on
TAM in 2D SoC. The Problem statement is described in section III. Mathemtical
model referred to establish the problem statement is shown in section IV, whereas
section V discusses the experimental result analysis. Finally, section VI draws the
conclusion.
2. PRIOR WORK
Mainly there are three kinds of test access architectures [3]. 1. Multiplexing, 2.
Distribution and 3. Daisychain architecture [4]-[7]. By using these architectures, a test
bus and TestRail architecture were proposed in [8] and [9] respectively.
A novel approach to reduce the test time of SoC is proposed in [10], which is
based on genetic local search algorithm. The proposed method resolves the problem
of TAM under the restriction such as core cluster and core placement cluster. The
method allows the system designer to improve TAM and helps to make appropriate
choices.
Another approach to reduce test time based on the bandwidth matching concept is
shown in [11], which emphasizes the multi-frequency TAM design. Using the method
of serialization and deserialization, a high bandwidth source and sink are connected to
the low bandwidth source and sink until bandwidth matches. In the second approach,
the problem with the post-silicon validation method, which has limited debug access
bandwidth to access internal signals, is described in [12].
The TAM based on flexible width architecture is shown in [13]. In this method,
first lower bound of test time is set which does not depend on TAM structure and then
the test bus assignment is done in such a way that, it achieves that lower bound.
A TAM for the multiple identical cores is shown in [14], which utilize the uniform
nature of the core and applies test simultaneously, which helps to minimize test time
for core under test. In an another approach, testing of multiple identical core is done
in such a way that, instead of taking typical test response data from the core, it takes a
majority based value. The TAM architecture introduced in this paper is based on-chip
comparator and majority analyzer [15] [16]. Reconfiguration of the multiple scan
chain to minimize test application time for SoC is presented in [17].
Here, the whole paper is designed for the optimization of TAM for the test bus
architecture. The architecture and results discussed in [18] and [19] is taken as a
reference. The algorithm described to optimize Wrapper and TAM in test bus
architecture is again developed and improved to get a further reduction in the test
application time.

An Efficient Algorithm For Wrapper and Tam Co-Optimization To Reduce Test Application
Time In Core Based SOC
3. PROBLEM STATEMENT
For the given NC number of cores for the SoC, including ni number of inputs, mi
number of outputs, TAM width W, SC number of scan chain and length of scan chain
lik for each core and Pi number of test patterns, determine (i) The improved width of
TAM bus (ii) ideal partition for TAM bus (iii) The assignment of cores to the
partitioned TAM bus and (iv) The test schedule for the entire SoC, such that overall
test application time is minimized.
4. MATHEMATICAL MODEL
Initialization
Let the total number of cores are NC
Total number of input for a particular core is - n
Total number of output for a particular core is – m
Number of test pattern given in a particular core is - P
TAM width allocated is – W
Number of partition taken for TAM width W is – B
So, Width distribution is taken as if partition factor is two
W1(i) = i
W2(i) = W- i
Where i varies from 1 to W/2
Here, a new variable ø is defined as
Ø(i) = max(n(i),m(i))
Where i varies from 1 to NC
Balance Wrapper Scan Chin
Lets number of scan chain inside a particular core is Sc.
Length of each scan chain is given as l1,l2…..lsc
Number of scan chain of length l1,l2…lsc is Z1,Z2….Zsc
Now divide number of scan chain Z1,Z2…..Zn by width W and find quotient an
remainder.
Q1=Z1/W R1 = Z1%W
Q2=Z2/W R2= Z1%W
Qn=Zn/W Rn=Zn%W
Here, Quotient indicates that these many scan chain can be equally distributed on
TAM width W.
Remainder indicates that these many scan chains are needed to be distributed
separately.
Now take the sum of the remainder
Rsum=

If Rsum<W, Then
Sum2(i)= + R(i)
Now, distribute and add number of I/O to sum2(i) such that the balance wrapper
scan chain is formed.
Sum3(i) = + m/W
Now find longest and shortest scan chain length
Simax = max(Sum3(i))
Where i varies from 1 to Sc
Simin = min(Sum3(i))
If Rsum>W, Then
Now, distribute and add remainders and number of Inputs to sum2(i) such that the
balance wrapper scan chain is generated.
Sum3(i) = + m/W + R(i)
Now find longest and shortest scan chain length
Simax = max(Sum3(i))
Simin = min(Sum3(i))
Simax and Simin is the balance input wrapper scan chain
Repeat this procedure for Balance output wrapper scan chain to find out Somax and
Somin
Test Time Calculation
Calculate test application time of each core for width W1 as per the equation given
below and store it in array A
A(i) = (1+max(Simax,Somax))*P + min(Simin,Somin)
Calculate test application time of each core for width W1 as per the equation given
below and store it in array B
B(i) = (1+max(Simax,Somax))*P + min(Simin,Somin)
Test Scheduling
Sort array A and array B in Descending order.
Calculate cumulative test time of all cores from array A
P1 =
Calculate cumulative test time of all cores from array
P2 =

P=min(P1,P2)
Take P as a upper bound for further procedure
Now, add array A and B
C(i)= +
If number of cores is greater than 10 then distribute cores into number of
segments. The first segment must contain 10 cores. The succeeding each segment may
contain up to 10 cores.
Here, the model is shown for 3 segments with assumption that there are 30 cores
in a SoC.
Store the test time for the first 10 core in an array X
X1(k)=C(i)
Where i and k varies from 1 to 10
X2(k)=C(i)
Where i varies from 11 to 20 and k varies from 1to 10
X3(k)=C(i)
Where i varies from 21 to 30 and k varies from 1to 10
Test scheduling for segment 1:
Upper bound for test time is PH = P
Lower bound of the test time is given as
PL =
Find the sum of the test time of the cores in array X1 for a given limit of upper
and lower bound and store it in array D1.
Find the sum of the test time of the cores in array X1a for a given limit of upper
Find the sum of the test time of the cores in array X1b for a given limit of upper
Find the length of D1.
L1=length(D1)
Find maximum from array D1, D2 and D3
EH1 = max(D1)
EH2 = max(D2)
EH3 = max(D3)
Upper bound = EH1
Lower bound = EL =
Where i varies from 21to 30
and lower bound and store it in array F1.

Find the length of F1.
L1=length(F1)
Initialize a variable k1=1
Upper bound = F1(i)
Where i varies from 1to L2
Lower bound = EL = C(Nc)
and lower bound and store it in array G1(k1) and update array for every iteration from
i =1 to L2. Also update k1.
i =1 toL2. Also update k1.
i =1 toL2. Also update k1. Find the length of G1 and update the values of last array.
L3=length(G1)
H1(j)=
H2(j)=
H3(j)=
Update j and H1,H2,H3 for every iteration.
Now, take P, EH2 and EH3 from segment 1
J1(i) = )
J2(i)=P-
Find maximum from two array J1 and J2
J(i)= max(J1(i),J2(i))
Where i varies from 1 to L3
Find Minimum value fro array J
Q=min(J(i))
Find Minimum value fro array J
Q=min(J(i))
Q is the final answer
5. EXPERIMENTAL RESULT ANALYSIS
Here SoC d695 and P93791 is taken as a running example throughout this paper to
understand the fundamental of test optimization methodology.
Here the experimental results are shown in table I, II and III when TAM bus width
is partitioned by 2. Also, the proposed method is compared with the reference

approach [18] and [19] which shows the optimality of the proposed method.
Simulation results achieved in this paper are done in MATLAB.
6. CONCLUSION
In this paper, an improved algorithm for the test bus architecture is presented and the
simulation is done on SoC d695 and P93791. Through extensive simulation on given
SoC, it is observed that with the proposed algorithm, the testing time is reduced
significantly as compared to the approach given in the reference. It has also been
noticed that the achieved TAM bus width distribution and core assignment is an
optimum value for the testing time earned with the proposed algorithm.
Table I Simulation results for SoC D695
Total TAM
Width
Optimal Width
Distribution
From ref paper
[18]
(No. of clocks)
From proposed
algo
(No. of clocks)
Difference
(No. of clocks)
16 (7,9) 45055 44116 939
20 (4,16) 34444 34437 7
24 (5,19) 29501 29240 261
28 (8,20) 26964 26828 136
32 (12,20) 25442 24779 663
36 (16,20) 25312 23193 2119
40 (8,32) 21359 21314 45
44 (9,35) 20883 20232 651
48 (10,38) 19938 19707 231
52 (18,34) 19087 18783 304
56 (20,36) 18434 18130 304
60 (20,40) 18205 18019 186
64 (20,44) 18205 17946 259
Table II Simulation results for SoC P93791 (Comparision with ref paper [18])
Total TAM
Width
Optimal Width
Distribution
From ref
paper[18]
(No. of clocks)
From proposed
algo
(No. of clocks)
Difference
(No. of clocks)
16 (8,8) 1806550 1683418 123132
20 (8,12) 1453170 1356828 96342
24 (12,12) 1217630 962058 255572
28 (5,23) 1031200 868112 163088
32 (9,23) 899807 867746 32061
36 (12,24) 820232 781852 38380
40 (16,24) 751345 707549 43796
44 (17,27) 711256 694132 17124
48 (23,25) 634488 589031 45457
52 (6,46) 600218 534109 66109
56 (9,47) 533752 505877 27875
60 (13,47) 505885 483857 22028
64 (16,48) 475598 464905 10693

Table III Simulation results for SoC P93791 (Comparision with ref paper [19])
Total TAM
Width
Optimal Width
Distribution
From ref
paper[19]
(No. of clocks)
From proposed
algo
(No. of clocks)
Difference
(No. of clocks)
16 (8,8) 1854566 1683418 171148
24 (12,12) 1272220 1134381 137839
32 (9,23) 940318 868112 72206
40 (16,24) 765715 706617 59098
48 (23,25) 640488 587775 52713
56 (9,47) 551849 494999 56850
64 (16,48) 473726 449967 23759
REFERENCES
[1] Y. Zorian, E. Marinissen, and S. Dey, Testing embedded-core-based system
chips,” Computer, vol. 32, no. 6, pp. 52–60, 1999.
[2] J. Marinissen, Y. Zorian, R. Kapur, T. Taylor and T. Whetsel, Towards a standard
for embedded core test: an example”, Proceeding of the International Test
conference, pp.616~627, 1999.
[3] K. Chakrabarty, “Optimal test access architectures for system-on-chip”, ACM
Transactions on Design Automation of Electronic System, Vol.6, no.1. January
2001, pp. 26~49
[4] V Iyengar, K. Chakrabarty, and E Marinissen, Test wrapper and test access
mechanism co-optimization for system-on-chip, Journal of Electronic Testing:
Theory and Applications, vol. 18, pp. 213–230, 2002.
[5] N. Nicolici and Xu, “Resource-constrained system-on-a-chip test: a survey,” IEE
Proc. Computers and Digital Techniques, vol.152, no. 1, pp. 67–81, 2005.
[6] Z. Peng, E. Larsson, K. Arvidsson and H. Fujiwara, Efficient test solutions for
core-based designs, TCAD, vol.23,no.5,pp.758–775, 2004.
[7] S Goel and E Marinissen, “Effective and Efficient Test Architecture Design for
SOCs”, In Proceedings IEE(ITC), pages 529–538, Baltimore, MD, Oct. 2002.
[8] S Bhatia and P Varma, “A Structured Test Reuse Methodology for Core-based
System Chips”, In Proc. ITC pages 294–302, 1998.
[9] J. Marinissen, “A Structured and Scalable Mechanism for Test Access to
Embedded Reusable Cores”, In Proceedings IEEE International Test Conference
(ITC), pages 284–293, Oct. 1998.
[10] W. Huang, Y Wang, “Optimizing Test Access Mechanism Under Constraints by
Genetic Local Search Algorithm”, Proc. ATS, 2003.
[11] N. Nicolici,Q. Xu, “Multi-frequency Test Access Mechanism design for Modular
SOC Testing,” In Proceedings 13th ATS, pp. 2-7, Nov. 2004.
[12] X Liu, Q Xu, “On Reusing Test Access Mechanisms for Debug Data Transfer in
SoC Post-Silicon Validation”, Proceeding IEEE Asian Test Symposium, pp-303-
308, 2008
[13] F Jianhua, L Jieyi, X Wenhua and Y Hongfei, “An Improved Test Access
Mechanism Structure and Optimization technique in System-on-Chip”,
Proceedings of the 2005 Asia and South Pacific Design Automation Conference,
Pages 23-24,2005

[14] G. Giles, J. Wang, A. Sehgal, K. Balakrishnan, and J. Wingfield, “Test access
mechanism for multiple identical cores,” in Proc. IEEE Int. Test Conf., Oct.
2008, pp. 1–10.
[15] A Han, I Choi, and S Kang, “Majority-Based Test Access Mechanism for Parallel
Testing of Multiple Identical Cores”, IEEE transaction on VLSI Ssystems, pp-1,
2014
[16] H Ke, D Zhongliang, H Jianming, “Boundary Scan with Parallel Test Access
Mechanism”, The Ninth International Conference on Electronic Measurement &
Instruments, pp – 16-19,2009
[17] J Rau, P Wu, W Huang, C Chien and C Chen, “Optimal Test Access Mechanism
(TAM) for Reducing Test Application Time of Core-Based SOCs”, Tamkang
Journal of Science and Engineering, Vol. 13, No. 3, pp. 305_314 , 2010
[18] K Chakrabarty V. Iyengar, A. Chandra, “Test resource partitioning for system-
on-a-chip.” Frontiers in Electronic Testing, Vol. 20, 2002.
[19] S Goel, J Marinissen, A Sehgal and K Chakravarti “Testing of SoCs with
Hierarchical Cores: Common Fallacies, Test Access Optimization, and Test
Scheduling “IEEE Transactions On Computers, Vol. 58, No. 3, March 2009

AN EFFICIENT ALGORITHM FOR WRAPPER AND TAM CO-OPTIMIZATION TO REDUCE TEST APPLICATION TIME IN CORE BASED SOC

More Related Content

What's hot (20)

Similar to AN EFFICIENT ALGORITHM FOR WRAPPER AND TAM CO-OPTIMIZATION TO REDUCE TEST APPLICATION TIME IN CORE BASED SOC (20)

More from IAEME Publication (20)

Recently uploaded (20)

AN EFFICIENT ALGORITHM FOR WRAPPER AND TAM CO-OPTIMIZATION TO REDUCE TEST APPLICATION TIME IN CORE BASED SOC