Electronic test
Design for Testability Standards
Part of
“New Media and e-Science” MSc Programme
Fall semester, 2004/2005
Franc Novak
Jožef Stefan Institute
Ljubljana, Slovenia
Course contents
•
•
•
•
•
design automation
essential issues in synthesis
design description
high-level synthesis algorithms
electronic test and testable design
electronic test and testable design
•
•
•
•
test challenges
design-for-test
standardized solutions
experimental boundary-scan environment
increased complexity
Moor’s law (1965) continues to hold:
the number of transistors on a square
inch of silicon doubles every 12 months
at the late 1970s: 18 months
at 2000: 18 to 24 months
(M.L.Bushnell, V.D.Agrawal:
Essentials of Electronic Testing)
increased transistor density in comparison
with the number of pins
d
number of transistors Nt = d2
number of I/O pins Np = 4d
d
increase of test complexity: Nt / Np
(1997-2001) Nt / Np = 1.1 x 104
(2003-2009) Nt / Np = 2.6 x 104
(2009-2012) Nt / Np = 6.7 x 104
increased speed and ATE cost
microprocessor clock
ATE signal generation/data capture
installed ATE (typical)
current ATE cost
SIA roadmap: prices of ATE
expected ATE cost by 2010
> 1GHz
~ 1.6 GHz
100 MHz
~ 3000$ per pin
20 million $
50 million $
Design for testability (DFT)
The difficulty of testing can be qualified in terms of
• cost of test development,
• cost of test application,
• cost (or economic consequences) of test escape.
The Rule of Ten: The cost of discovering a defective chip increases
by an order of magnitude at each successive level of integration,
from die/ package, board and system.
Design for testability is defined as changes to a given circuit or
system design that make the overall testing less difficult.
Testability measures
• Controllability of a digital circuit is defined as the difficulty of
setting a particular signal of the circuit to logical 0 or 1.
• Observability of a digital circuit is defined as the difficulty of
observing the state of a particular signal of the circuit.
Testability = controllability + observability
Testability analysis
• involves circuit topological analysis,
• does not involve test vectors,
• has linear complexity.
Goldstein(1979): SCOAP Controllability and Observability
Embedded test approach
test pattern generation
result compression
• test pattern generation using Linear Feedback Shift Register
(LSFR)
• result compression using LSFR response compactor
(R.A.Frohwerk “Signature analysis: A new digital field service method”, Hewlett-Packard
Journal, 1977
test of embedded memories
Conventional ad-hoc techniques
• additional logic to route the embedded memory inputs/outputs to
external pins
• a scan chain around the embedded memory
Alternative way
• memory BIST approach with on-chip (on-board) generation of test
patterns and compression of test results
S.K.Jain, C.E.Stroud “Built-in self-testing of embedded memories”, IEEE
Design & Test of Computers, 1986
problems
In-circuit test: problems in mechanical access
• complex ICs with smaller pin-to-pin spacing
• decreased distance between PCB interconnects
• direct mounting of chips on both sides of a PCB
solution
to build the test probe directly into the silicon chip
IEEE Std 1149.1
boundary-scan principle:
• a shift register boundary
cell is placed adjacent to
each component pin
• boundary-scan cells are
interconnected into a shift
register
IEEE Std 1149.1
components on a board are connected via one or more serial boundaryscan lines
IEEE Std 1149.1
mandatory instructions:
• external test
• sample/preload
• bypass
non-mandatory instructions:
• intest, runbist, clamp,
idcode, usercode,etc.
IEEE Std 1149.1- extest
IEEE Std. 1149.1
More information:
• 1149.1-2001 Test Access Port and Boundary-Scan
Architecture (IEEE), IEEE catalog number: ST01120,
212 pages. 2001. ISBN 0-7381-2994-5
• Kenneth P. Parker: The Boundary-scan Handbook,
second edition, Kluwer Academic Publishers, ISBN 07923-8277-3
• Harry Bleeker, Peter van den Eijnden, Franc de Jong:
Boundary-scan Test, A Practical Approach, Kluwer
Academic Publishers, ISBN 0-7923-9296-5
IEEE Std 1149.4
can be regarded as extension of IEEE 1149.1 to mixed-signal test
IEEE Std.1149.4 (Mixed-Signal Test Bus)
Analog Boundary Module (ABM)
IEEE Std. 1149.4
This standard defines features that provide standardized approaches to:
• interconnect test (testing for opens and shorts among the
interconnections in a printed circuit assembly)
• parametric test (analog characterization measurements, and testing
for presence and value of discrete components in a printed circuit
assembly)
• internal test (testing the internal circuitry of the mixed-signal chip)
IEEE Std.1149.4
mandatory instructions:
• external test
• sample/preload
• bypass
(these instructions are already defined by IEEE 1149.1)
aditional mandatory instruction:
• probe instruction allows analog pins to be monitored
on the analog bus and/or stimulated from the analog
bus during normal operation
IEEE Std. 1149.4
More information:
• IEEE 1149.4 Mixed-Signal Test Bus Working Group:
http://grouper.ieee.org/groups/1149/4/
• An overview of the standard, along with a discussion of
the architecture and how to use it :
http://grouper.ieee.org/groups/1149/4/basic_present.ppt
• Adam Osseiran: Analog and Mixed-Signal BoundaryScan: A Guide to the IEEE 1149.4 Test Standard,
Kluwer Academic Publishers, 1999
System-on-chip(SOC)
• pre-designed, pre-verified, reusable building blocks:
embedded cores
• shortened design cycle, higher performance, lower
power consumption, smaller volume
Embedded core types
• Soft core (RTL code)
• Firm core (netlist)
• Hard core (layout)
• Intellectual Property (IP) !!!
System-on-chip(SOC) test problems
• Production test of assembled boards consists of a sequence of
separate test steps: component tests, bare board test, static test
of assembled board (detecting shorts and opens) and dynamic
functional test (detecting timing faults).
• In the case of testing SOC, all the above tests are merged into
one composite test instance.
• Furthermore, in most cases direct access to the core terminals
is not provided which makes it difficult to run internal tests of
deeply embedded cores.
IC tester
Towards SOC test problem solution
• Core provider and core user must cooperate
• Standardized interface for core test knowledge
transfer
• IEEE Std. 1500 Standard for Embedded Core Test
Conceptual architecture for testing
embedded-cores
wrapper interface
IEEE Std. 1500 instructions
•
•
WS_EXTEST (mandatory) allows test of external interconnections
WS_BYPASS (mandatory)
•
•
•
•
•
WS_INTEST_RING (optional)
WS_INTEST_SCAN (optional)
WP_INTEST_RING (optional)
WP_INTEST_SCAN (optional)
WH_INTEST (optional)
•
•
•
•
•
•
WS_PRELOAD (optional)
WP_PRELOAD (optional)
WS_CLAMP (optional)
WS_SAFE (optional)
WP_EXTEST (optional)
WH_EXTEST (optional)
these instructions perform internal test
at least one of them is mandatory
IEEE Std. 1500
More information:
• IEEE P1500 Standard for Embedded Core Test (SECT)
http://grouper.ieee.org/groups/1500/
• Scaleable Architecture
http://grouper.ieee.org/groups/1500/date03/ctag-date03.pdf
Available test environments
• boundary-scan environment (EBS)
• sequential diagnosis tool
• remote access - Agilent 83000 test system
boundary-scan environment (EBS)
SN74ACT8990 boundary-scan controller
boundary-scan test example
boundary-scan test example 2
IEEE 1149.1 test programming
boundary-scan bus operations described by IEEE state diagram
SN74BCT8245A test programming
EBS software
Linux OS:
• device drivers
- SN74ACT8990 boundary-scan controller,
- parallel port (in preparation)
• test development tools
- Serial Vector Format (SVF) parser
Serial Vector Format
•
•
•
SVF is the media for exchanging descriptions of high-level IEEE Std.
1149.1 bus operations
SVF description: scan operations and movements between different
stable states of the IEEE state diagram
SVF encourages reuse and portability of serial vectors
(Texas Instruments Inc. 1994, ASSET InterTech Inc.)
Serial Vector Format commands
Serial Vector Format parser
a simple test program example
possible applications
education:
• integrity test
• interconnection test of a proto board, injected faults (shorts between lines,
open lines)
research projects
• experimental verification of new designs including boundary-scan
• IEEE Std. 1149.4 test and measurement techniques
EuNICEtest Project
•
European Network for Initial and Continuing Education in VLSI/SOC
Testing using remote ATE facilities
•
coordinator: Laboratoire d’Informatique, de Robotique et de
Microélectronique de Montpellier (LIRMM)
•
partners: Universitat Politecnica de Catalunya, Politecnico di Torino,
University of Stuttgart, Jozef Stefan Institute, Agilent Technologies
EuNICEtest Project
Literature
General background:
• Franklin P. Prosser, David E. Winkel: The art of digital design, Prenticehall int. editions, ISBN 0-13-046673-5
High-level synthesis:
• Daniel Gajski, Nikil Dutt, Allen Wu, Steve Lin: High-level synthesis,
Kluwer Academic Publishers, ISBN 0-7923-9194-2
• Giovanni De Micheli: Synthesis and optimization of digital circuits,
McGraw-Hill, ISBN 0-07-016333-2
Electronic test:
• Michael L. Bushnell, Vishwani D. Agrawal: Essentials of Electronic
Testing, Kluwer Academic Publishers, ISBN 0-7923-7991-8