3 STL overview
STL is an application-independent software test library released by ST to implement a relevant subset of safety
mechanisms required by the safety concepts applicable to microcontrollers of the STM32H7 Series. The STL is
HAL/LL independent, and dedicated to the STM32H7 Series. The STL is compilation tool chain-agnostic, so it can
be compiled by any standard C-compiler.
STL is an autonomous software, which executes on application demand selected tests to detect hardware issues,
and reports the outcomes to the application.
STL is delivered partly in object code (for the library itself) and partly in source code for the user interfaces
definition and user parameters settings.
3.1 Architecture overview
The STL tests the CPU Arm
®
core, the Flash memory and the RAM.
As shown in Figure 1. STL architecture, a system architecture with an end-user application integrating the STL is
composed of:
• User application (in light blue)
• User parameters (in light blue)
• STL scheduler (in light yellow): directly accessible by the User application via User APIs (not going through
HAL/LL)
• STL internal test modules (in light yellow): called by the STL scheduler (not seen from the User application).
The STL status information returned to the User application at API level (see Table 3. STL return information) are:
• function return values (STL_OK, STL_KO)
• test module result values (STL_PASSED, STL_PARTIAL_PASSED, STL_FAILED, STL_NOT_TESTED,
STL_ERROR).
Figure 1. STL architecture
STL
User
parameters
STL
User
APIs
STL scheduler
Function return value
Test result value
User application
HAL/LL
STL
CPU Arm® core
test module x
STL
Flash memory
test module
STL
SRAM
test module
STM32 microcontroller
User tests
APIs
User tests
Legend:
STL
User
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UM2601
STL overview
UM2601 - Rev 3
page 4/71
