Functional safety requirements for application software

AN4475

18/27

DocID026216 Rev 1

2.19

All safety relevant modules

Suggested: [covers: SW_CRC_CONF_REG] CRC signature iss used to check the

correctness of the content of the configuration registers of each safety-related module. This

check runs once per FTTI. [end]

Implementation hint: E.g. the CRC signature of the content of the configuration registers of

each safety-related module is calculated off-line. At run time, the same CRC signature is

calculated by software within the FTTI. The run-time calculated CRC signature is then

compared to the expected one, i.e. the off line calculated CRC signature. CRC signature

could be calculated by software using one or more industry standard CRC algorithms. To

avoid CPU overloading, the EDMA module can be used to support the data transfer from

the registers under check to the RAM.