SoC Test Architecture with RFWireless Connectivity

1
SoC Test Architecture with RF/Wireless
Connectivity

• D. Zhao, S. Upadhyaya, M. Margala, A new SoC
  test architecture with RF/wireless connectivity,
  in Proceedings of the European Test Symposium
  (ETS05), pp. 14-19, 2005.

2
Overview

• Paper proposes new SoC test network
• Uses distributed multihop wireless test control
  network
• Radio-on-Chip technology
• Initial Research for complete application and
  implementation in 4-6 years
• Studies system design issues
• RF node placement
• Clustering
• Routing
• Discusses system optimization
• TAM design
• Test scheduling

3
Motivation

• Future SoC design involve integration of numerous
  heterogeneous Intellectual Property cores
• Future Problems
• Non-scalable global wire delays
• Failure to achieve global synchronization
• Errors from signal integrity issues
• Bandwidth limitations
• Difficulties associated with wired interconnects

4
Technology for Possible Solution

• Radio frequency (RF) interconnect technology for
  future intra-chip communications
• Goal wireless radios replace wires
• Increase accessibility
• Improve bandwidth utilization
• Eliminate delay and cross-talk noise from wired
  interconnect
• RF interconnect is very new
• Usefulness investigated in this paper and future
  research

5
SoC Test Challenges

• Accessing deeply embedded cores with high-speed,
  high-efficiency, and low-cost interconnect
  structure
• Partitioning test resources and scheduling IP
  cores to achieve maximum parallelism
• Developing a high-efficiency, low-cost control
  network to execute the test application based on
  a predetermined schedule

6
Proposed Solution

• Wireless radios transmit
• Test data
• Control signals
• To access deeply embedded cores
• In conjunction, a new SoC test strategy needs to
  be developed
• Uses short range, low-power, low cost wireless
  network
• To schedule core and chip level tests
• Used for the entire chip test control
  communication

7
MTCNet

• Multihop wireless test control network (MTCNet)
• Reduce transmission power
• Avoid chip overheating
• Efficient control processing
• Tree Structure
• Scheduler at root
• RF nodes at vertices
• IP cores at leaves
• For parallel test control
• Subcontrollers cover subnetworks under
  supervision of scheduler.

8
System Resource Distribution

• System resources in an SoC consist of two parts
• Test Control Distribution
• RF nodes in the intra-chip wireless test control
  network
• Test Resource Distribution
• Circuit blocks required to perform a test
• Focuses on optimal routing of TAM from a
  dedicated test source to core-under-test to
  dedicated test sink

9
Test Control Distribution

• Cluster of IP cores share 1 on-chip RF node
• Maximum coverage of RF nodes determines
• Number of RF nodes needed in the SoC
• Wiring between RF nodes and the cores
• Disk covering algorithm for optimal node placement

10
TAM Routing

• Case (a)
• Cores connected on the same TAM belong to
  different clusters
• Concurrent testing of A B
• Unicast control signal to RF 1
• Signal forwarded to A B along hard-wires

11
TAM Routing

• Case (b)
• Cores connected on the same TAM belong to same
  cluster
• Concurrent testing of A B
• Multicast control signal to RF nodes 1 2
• Uses two separate wireless routing paths

12
TAM Routing

• Case (c)
• Combination of case (a) and (b)
• (b) has less TAM routing than (a)
• (b) has more control routing due to multicasting

13
Goal of Optimal TAM Routing

• Reduce the overall test application time with
  efficient test scheduling algorithm
• Connects the IPs in SoC to test sources and sinks
• Compatible tests routed on parallel TAMs
• Cores competing for the same test resource
  connected sequentially on same TAM

14
Simulation Study

• Experimental results for the proposed algorithm
• SoC d695 from ITC02 SOC Test Benchmarks
• Floorplan of cores on-chip is randomly generated

15
Simulation Study

• Column Definitions
• Wmax Max TAM width
• Tappl Overall test application time
• CTAM TAM routing cost
• Ccontrol test control routing cost
• Call Overall Testing Cost

16
Conclusions

• Presented system optimization technique for
  integration of resource distribution
• RF links
• TAM routing to minimize overall testing cost
• Future Work
• Address system optimization problem
• Evaluate impact of wireless test control on
  system testing solution

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Simulation Study