AN3307 datasheet(18/37 Pages) STMICROELECTRONICS

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Class B software package

AN3307

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Doc ID 18186 Rev 4

Figure 3.

Diagnostic LED timing signal principle

4.3

Package configuration and debugging

Sometimes a functional part of the package should be suspended, excluded or included.

The reason could be that certain tests are not required for a given application context. Some

modifications can also useful when the package has to be debugged. This section describes

how the ST solution can be configured, modified and debugged.

4.3.1

Configuration control

Configuration of the software is done at two basic levels. One configuration level is given by

the project settings, where the differences between the STM32 family members is the factor.

This part is mainly done automatically by proper configuration of the project. The other

configuration level is the user settings. All user configuration settings are centralised in the

Class B configuration file stm32fxxx_STLparam.h. A set of constants defined in this file

control the conditional compilation of some functions. Adjustable constants must have

specific settings to run all the tests properly (see note at Chapter 4.2.1: Projects included in

the package).

Some runtime tests can be skipped depending on the end application. If the periodicity of

the test is inherent (for example, for a washing machine, users switch the application on or

off when it is used), then power on tests are sufficient and transparent/runtime tests can be

avoided. This point must be discussed with the chosen test institute case by case.

For maximum robustness, the recommendation is to enable the independent watchdog

using the hardware option bytes, and start the window watchdog as soon as possible in the

main routine once the application development is close to the end. This is not done by

default in the STM32 self-test library demo.

Stack overflow detection and watchdog self-check are not mandatory according to the

EN/IEC60335-1 standard. They can be disabled or skipped if necessary.

It can help decrease the CPU load during runtime if 32-bit CRC checks are made using the

STM32’s internal CRC generator (32-bit wide CRC computation using the standard

0x04C11DB7 polynomial). Today KEIL compiler does not support CRC format directly, but it

can be used in conjunction with 16-bit CRC. One possible method could be to compute a

32-bit checksum in the initial phase and validate it using 16-bit CRC computation compared

with the linker result. The validated 32-bit CRC value can be then saved as a reference for

comparing all the subsequent runtime checks.

Complete Class B test period

Partial test

period

Partial test

duration

AI18002

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