General Description
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SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Self-Test Controller (STC) Module
10.1 General Description
The self-test controller (STC) module is used to test the ARM CPU core and other complex digital IPs
using the 'Deterministic Logic Built-in Self-Test' (LBIST) controller as the test engine. To achieve better
coverage for the self-test of complex cores like Cortex-R5F, on-chip logic BIST is the preferred solution
over software based self-test.
There are two STC modules implemented on this device. STC1 for redundant CPUs and their µSCU
block. STC2 for the two nHET modules. The STC module provides the capability to test redundant IPs in
parallel or individually.
10.1.1 Self-Test Controller Features
The self-test controller has the following features:
•
Capable of running the complete test as well as running a single or multiple test sets (intervals) at a
time.
–
Ability to continue from the last executed interval as well as the ability to restart from the beginning
(first interval).
•
Support of two logical segments.
shows the implementation with multiple segments. Each
interval can be mapped to a logical segment. A segment identifier corresponding to each interval is
stored in the self-test ROM.
–
Segment 0: Segment 0 has the additional capability to test redundant logic or cores in one of the
following modes:
•
Parallel Mode: Redundant logic cores are tested in parallel with the same patterns but have a
dedicated signature generator. This is used in the safety critical redundant logic that runs in
lock-step.
and
show this configuration for STC1 and STC2.
•
Split Mode: Each redundant logic is tested individually.
and
show this
configuration for STC1.
–
All redundant cores (or IPs) within a segment have their own dedicated DBIST controllers.
–
Other segment (segment 1) can test only a single logic segment during the self-test run.
–
Ability to select segment for which the first interval is selected for run.
•
Complete isolation of the self-tested core from the rest of the system during the self-test run
–
The self-tested CPU core master bus transaction signals are configured to be in idle mode during
the self-test run
–
Any master access to the CPU core under self-test (example: DMA access to CPU TCM) will be
held until the completion of the self-test
•
Ability to capture the failure segment and interval number
•
Timeout counter for the self-test run as a fail-safe feature
•
Able to read the MISR data (shifted from LBIST controller) of the last executed interval of the self-test
run for debugging purposes
•
STCCLK determines the self-test execution speed, STC clock divider (STCCLKDIV) register is used to
divide one of the system clocks to generate STCCLK. The divider can be configured per segment. For
STC1, GCLK1 is divided down; for STC2, VCLK2 is divided down to generate STCCLK.
•
Low-frequency shift. Programmable clock divider register inside STC to reduce the shift frequency in
order to reduce the shift power.