Overview for Initialization Process April 27, 2010

Configurable I/O Since the original development of the Boundary Scan standard, the complexity and variation of I/O cells as well as the ICs themselves has greatly increased in the digital IC industry Process technology advancements have reduced the safe operating voltage ranges of transistors I/Os are now configurable for the electrical characteristics such as power levels, drive strength, VIL/VIH, impedance, etc. Unused I/O may be configured to be power downed and to not actually be capable of receiving logic values placed on the pin for lower power modes In both mission and test modes, I/Os frequently require configuration before they can be used

Boundary Scan Operation Failures I/O cannot correctly drive or receive a logic 1 or 0 until the correct configuration for the given instance is loaded and known Mismatched configurations of I/Os on a board could cause a driven logic 1 to be received as a logic 0 In mission mode, a powered-off I/O analog cell cannot SAMPLE the pin value to the BSR Until an Initialization Procedure is completed to program or configure the I/O, none of 1149.X instructions which control or observe the pins can be reliably depended on to correctly operate

IC Initialization for “Safe” operation for Board-level Interconnect Test It may be desirable or necessary to place an IC into a “safe” mode during Board-level tests If board interconnect tests are performed before attachment of heat sinks, it may be necessary to power down large portions of IC core for thermal management To reduce power consumption, PLLs may need to be disabled during board level interconnect testing Without setting the I/O voltage level program correctly, incorrect applied input signal voltage may permanently damage an I/O cell Chips with Secure information may require the deletion of data before Boundary operations

Initialization Procedure All of these issues can be resolved by Initialization procedure The proposed Initialization procedure support needs to allow for the following: Optional parameterized configuration by setting data in a TDR (INIT_DATA) Optional specification a minimum number of TCKs (or other time value) for configuration completion to take effect (either for a state machine execution or a “settling time”) Option to receive status bits Option to “poll” for earlier completion Control of when the mission mode is disrupted

Overview 2 instructions: INIT_SETUP (optional INIT_DATA TDR) INIT_RUN (optional INIT_STATUS TDR) Run after POR, before EXTEST NOT dependent on RTI TAP state BSDL to document the data fields of INIT_DATA) with optional mnemonics for field values, Completion time, and optional expected results (format, content TBD) Side file to specify per chip instance initialization data and expected results

Board Test Control of Chip State During Test Board tests consist of series of based tests Each test starts and ends at Test-Logic-Reset during potential glitching of TRST* during transition between tests Need for a some optional persistence of a “Test Safe” state after a Test-Logic-Reset and before a normal mission-mode reset The INIT_DATA values can be re-usable TLR  INIT_SETUP  [INIT_RUN]  EXTEST  TLR  [INIT_RUN]  EXTEST The Test Safe state should tend to persist

Modes of Usages Initialization can be used under different types of usages across different chips on the same Boundary scan chain at the board level No Initialization required (Chips stay in BYPASS) Direct Parameterization: with INIT_SETUP only, followed by EXTEST (No Completion Time requirement) Simple State Machine Execution: INIT_RUN only with Completion Time required followed by EXTEST (No parameterization required) Parameterized State Machine Execution: Initialization with INIT_SETUP for parameterization, then INIT_RUN for Completion Time before EXTEST

BSDL Updates for Initialization BSDL will have new Attributes and Keywords for Initialization Update INSTRUCTION_OPCODE to add INIT_SETUP and INIT_RUN in Update REGISTER_STATUS to add INIT_DATA and INIT_STATUS Create REGISTER_MNEMONICS Attribute to describe optional mnemonics for data fields Create REGISTER_FIELDS to define the subfields of the INIT_DATA or INIT_STATUS register sub- fields

Side file The side file is specific to each instantiation of chip supporting Initialization on the board Side file would provide the parameterization required per instance Side file would facilitate tool inter-operability Based in based PDL constructs from P1687 File supplies the data values for the INIT_DATA values

Initialization Flow UpdateIR INIT_SETUP on chips which support it; other chips are in BYPASS ShiftDR INIT_DATA TDR to set parameters Parameters can control the electrical settings of the I/Os per board specifics IOs may support a wide range of electrical settings which may not be able to signal correctly without initialization Parameters can control system internals as well. e.g. power-downs, PLL Kill, etc. for safe operation

Initialization Flow PRELOAD instruction should be run before INIT_RUN to initialize the data path values At UpdateIR, INIT_RUN starts execution to place chip in state ready for EXTEST* Intrusive Internal state machines may be executing for a Completion time to do the state changes ShiftDR will shift either optional INIT_STATUS or BYPASS TDR The board must wait until last chip has completed Completion is define by either a Completion time or by a Done Status provided by INIT_STATUS TDR

Flow TestLogicReset Initial TAP State Some chips in BYPASS mode; chip state undisturbed UpdateIR INIT_SETUP / BYP UpdateIR INIT_SETUP / BYP Load INIT params per chip as needed into INIT_DATA Initialize the data values into the BSR ShiftDR INIT_SETUP / BYP ShiftDR INIT_SETUP / BYP UpdateIR / ShiftDR PRELOAD UpdateIR / ShiftDR PRELOAD

Any State of TAP Flow (Con’t) Initialization operating (not TLR) Some chips in BYPASS mode; INIT_STATUS or BYPASS output After max Completion Time or INIT_STATUS Done indicated EXTEST operation with correct data and electrical values INIT_RUN Done UpdateIR EXTEST* UpdateIR EXTEST* ShiftDR INIT_RUN / BYP ShiftDR INIT_RUN / BYP UpdateIR INIT_RUN / BYP UpdateIR INIT_RUN / BYP Invasive; FSM starting running if any chips need it