STIL - Standard Test Interface Langauge

Purpose: 

To support various interfacing needs for test generation tools (ATPG tools) and test equipments (ATE)  

• Standard Test Interface Language (STIL) Standardised as IEEE 1450
• Provides data exchange between EDA tools from different vendors and ATE interfaces
• STIL is an open source language 

STIL file Contents: 

Fig 1. Top level of STIL data model [1]

STIL - 

• Defines the version of STIL present in the file. 
• This is the first statement of any STIL file, including files opened from the Include statement.

Header -

• Contains general information about the STIL file being parsed. 
• This block is optional; if present, it shall be the first statement after the STIL statement in the file.

Signals -

• Defines all primary signals under test.

SignalGroups -

• Defines collections of Signals. 
• Requires reference to use if domain_name is used.

ScanStructures -

• Defines internal scan chain information. 
• The ScanStructures block or blocks are optional. 
• If there are multiple ScanStructures blocks, they must be named. 
• The PatternBurst may contain a reference to a named ScanStructures block, and the Pattern may contain a reference to a named ScanChain inside a ScanStructures. 
• These blocks shall be defined before the PatternBurst if the PatternBurst contains references; otherwise, these blocks are defined before the Pattern.

Spec -

• Defines values of variables to be applied in Timing Expressions. 
• Multiple values may be assigned to variables; variable values are not resolved until the PatternExec statement. 
• All Spec blocks shall precede the first Timing block definition.

Timing -

• Defines the waveforms to be applied to each signal in the test. 
• Timing expressions in this block may reference variables defined in Spec blocks, but timing variables are not resolved until the PatternExec. 
• Timing blocks may reference other timing blocks; those blocks shall be defined before they are referenced.

Selector -

• Selects min/typ/max/meas value of variables defined in Spec. 
• Although this references variables defined in Spec blocks, variable values are not resolved until the PatternExec statement. 
• This block shall precede the PatternExec block.

PatternBurst

• Defines all Patterns to be executed collectively; any operation performed on this data (such as timing assignment) is performed on all Patterns referenced in this domain. 
• The domain_name_pat reference, MacroDefs reference, and Procedures reference may all be forward references. 
• Any references to SignalGroups shall have those blocks defined first. This block shall precede the PatternExec block.

PatternExec -

• Resolves timing variables and waveforms to apply with pattern references from PatternBursts.
• This block binds all information into a form to be applied to patterns as they are parsed.

Procedures -

• Defines a set of test data to be used multiple times in a Pattern; at the end of each execution, the state of the test before this call is restored for the next test vector. 
• Procedure data may be processed after a PatternBurst referencing this block is parsed.

MacroDefs -

• Defines a set of test data to be used multiple times in a Pattern; at the end of each execution, the state of the test at the end of macro is in force. 
• Macro data cannot be processed until Patterns are processed; pattern context may affect macro processing.

Pattern -

• Defines test data. 
• All references shall be complete at the point pattern data is processed.

Example STIL file:

https://github.com/NTU-LaDS-II/FAN_ATPG/blob/main/pat/FAN_s1196.stil

Opensource Softwares:

1. STIL_Interpreter : https://github.com/gonsp/STIL_Interpreter

2. Semi-ATE/STIL:  https://github.com/Semi-ATE/STIL

References:

1. Standard Test Interface Language (STIL) - A New Language for Patterns and Waveforms by Tony Taylor 
2. IEEE 1450 Standard