Presentation on theme: "1. 2 Overview: Introduction Introduction SVF structure SVF structure SVF commands SVF commands SVF TAP state name used for each SVF TAP state name used."— Presentation transcript:
2 Overview: Introduction Introduction SVF structure SVF structure SVF commands SVF commands SVF TAP state name used for each SVF TAP state name used for each IEEE 1149.1 TAP state name. IEEE 1149.1 TAP state name. An example of SVF file An example of SVF file
3 Introduction: The original SVF was developed jointly by Texas Instruments and Teradyne in 1991. The need for SVF arose from the desire to have vendor-independent IEEE 1149.1 test patterns that are transportable across a wide selection of simulation software and test equipment -- from design verification through field diagnostics.
4 SVF is a standard ASCII format for expressing test patterns that represent the stimulus, expected response, and mask data for IEEE 1149.1-based tests. The underlying models of SVF format assume that all operations begin and end in stable state.
5 SVF has proven itself to be a useful and reliable format for exchanging data between the Boundary Scan TAP and the software that drives it.
6 SVF Structure: An SVF file contains a set of ASCII statements. The maximum number of characters allowed on a line is 256. One SVF statement can span more than one line. Each statement consists of a command and its associated parameters, terminated by a semicolon.
7 SVF isn’t case sensitive and comments are indicated by exclamation point (!) or a pair of slashes (//). Either '//' or '!' will comment out the remainder of the line. SVF is terminated with a carriage return. Scan data within a statement is expressed as hexadecimal and is always enclosed in parentheses.
8 SVF SVF commands can be grouped into three types: state commands. offset commands. parallel commands.
9 State Commands: State commands are used to specify how the test sequences will traverse the IEEE Std 1149.1 TAP state machine.
10 The following state commands are supported: ENDDR: Specifies default end state for DR scan operations. ENDIR: Specifies default end state for IR scan operations.
11 SDR = Scan Data Register : Performs an IEEE 1149.1 Data Register scan. SIR = Scan Instruction Register : Performs an IEEE 1149.1 Instruction Register scan. STATE: Forces the IEEE 1149.1 bus to a specified stable state.
12 RUNTEST: Forces the IEEE 1149.1 bus to a run state for a specified number of clocks or a specified time period. TRST = Test ReSeT : Controls the optional Test Reset line. i.e. It activates or deactivates the optional test-reset signal of the IEEE Std 1149.1 bus.
13 Parallel Commands: Parallel commands allow SVF to combine serial and parallel sequences.
14 The following parallel commands are supported: PIO = Parallel Input/Output : Specifies a parallel test pattern. PIOMAP = Parallel Input/Output Map : Maps PIO column positions to a logical pin.
15 Offset Commands: Offset commands allow a series of SVF commands to be targeted toward a contiguous series of points in the scan path.
16 The following offset commands are supported: HDR = Header Data Register : Specifies a header pattern that is prepended to the beginning of subsequent DR scan operations. HIR = Header Instruction Register : Specifies a header pattern that is prepended to the beginning of subsequent IR scan operations.
17 TDR = Trailer Data Register : Specifies a trailer pattern that is appended to the end of subsequent DR scan operations. TIR = Trailer Instruction Register: Specifies a trailer pattern that is appended to the end of subsequent IR scan operations.
18 Note #1: These patterns need only be specified once and are included on each scan unless changed by a subsequent HDR, HIR, TDR, or TIR command.
19 Note #2: A scan operation is defined as the execution of an SIR or SDR command and any associated header or trailer commands.
20 The following table lists each SVF state name used for each IEEE 1149.1 TAP state name:
21 Note #3: When transitioning from one state to another, there is no need to specify each state. For example, if the current state is RESET and DRPAUSE was selected as the end state, the TAP moves from RESET through IDLE, DRSELECT, DRCAPTURE, DREXIT1 to DRPAUSE. i.e. have to just specify the current and end states and not each intermediate step.
23 Note #4: The simplicity of SVF is also one of its major weaknesses.
24 An example of SVF file: !Begin Test Program TRST OFF; !Disable Test Reset line ENDIR IDLE; !End IR scans in IDLE ENDDR IDLE; !End DR scans in IDLE HIR 8 TDI (00); !8-bit IR header HDR 16 TDI (FFFF) TDO (FFFF) MASK (FFFF);!16-bit DR header TIR 16 TDI (0000); !16-bit IR trailer TDR 8 TDI (12); !16-bit DR trailer SIR 8 TDI (41); !8-bit IR scan SDR 32 TDI (ABCD1234) TDO (11112222); !32-bit DR scan STATE DRPAUSE; !Go to stable state DRPAUSE RUNTEST 100 TCK ENDSTATE IRPAUSE; !RUNBIST for 100 TCKs !End Test Program