General Description
430
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Self-Test Controller (STC) Module
10.1.2 Terminology
Interval: An interval corresponds to a test set that is the basic test unit for the STC module
Segment: A self-test segment corresponds to a portion of the unique/discrete safety critical logic which
can be tested in isolation from the rest of the system by the self-test controller and DBIST logic. A self-test
segment may correspond to a logic like CPU core (for example, Cortex-R5F) or an IP (for example, µSCU
or nHET) or a sub-system.
The assignment of segments to digital logic is device dependent.
NOTE:
All segments need to run sequentially during the self-test run. It is not recommended to
switch from one segment to another before the self-test for the current segment is
completed. The segment intervals in the STC ROM are organized sequentially.
10.1.3 STC Block Diagram
STC module provides an interface to the LBIST controller implemented on the CPUs and the nHET
modules. There are two separate STC modules implemented: one for redundant Cortex-R5F CPUs and
µSCU and another one for the nHET modules. Each STC module comprises of the same basic blocks and
has same features and functionality.
The STC module is composed of following blocks of logic:
•
ROM Interface
•
FSM and Sequence Control
•
Register Block
•
Peripheral Bus Interface (VBUSP Interface)
10.1.3.1 ROM Interface
This block handles the ROM address and control signal generation to read the self-test microcode from
the ROM. The test microcode and golden signature value for each interval are stored in ROM.
10.1.3.1.1 FSM and Sequence Control
This block generates control signal and data to the LBIST controller based on the seed, test_type and
scan chain depth.
10.1.3.1.2 Clock Control
The clock controller sub-block handles the internal clock selection and generation for the ROM, LBIST
controller and logic under test.
The clock control ratio can be programmed in STC module by programming STCCLKDIV register.
10.1.3.2 Register Block
This block handles the control of the self-test controller. This block contains various configuration and
status registers that provide the result of a self-test run. These registers are memory mapped and
accessible through the Peripheral Bus (VBUSP) Interface. This block controls the reseeding (reloading the
existing seed of the PRPG) in the LBIST controller.