Functional safety requirements for application software

AN4287

10/27

DocID024464

Rev 2

Interrupt Service Routine (ISR) code and missing interrupts, if they are synchronous, can be

detected checking the program flow.

3.7

Enhanced Direct Memory Access (eDMA)

Suggested: considering that no specific hardware protection is implemented against

failures in the eDMA, spurious/missing eDMA requests caused by Electromagnetic

Interference (EMI) or by bit flips in the interrupt registers of the peripherals, applications not

resilient against such errors shall include detection or protection software countermeasures.

These specific software countermeasures can run once after the Power-On Reset (POR)

before running the SIF.

Rationale: to verify eDMA requests are serviced correctly.

Implementation hint: specific software countermeasures shall be implemented to detect

eDMA permanent faults. These specific software countermeasures are application-

dependent.

3.8

Communication peripherals

The SPC564A7x/SPC564A80 includes the following communication peripherals:

•

FlexCAN;

•

Deserial Serial Peripheral Interface (DSPI);

•

FlexRay Communication Controller (FlexRay);

•

Enhanced Serial Communication Interface (eSCI).

Suggested: an appropriate safety software protocol should be utilized (e.g. Fault Tolerant

Communication Layer or FTCOM) for any communication peripheral employed to meet

safety application requirements.

3.9

I/O peripherals

The SPC564A7x/SPC564A80 includes the following I/O peripherals:

•

System Integration Unit Lite (SIUL);

•

Configurable Enhanced Modular IO Subsystem (eMIOS200);

•

Enhanced Time Processing Unit (eTPU2).

These modules shall be used to implement the following functions if they are part of the

application:

•

Read digital inputs;

•

Read PWM inputs;

•

Write digital outputs;

•

Write PWM outputs.

3.9.1

Read digital inputs

Suggested: digital inputs shall be acquired redundantly. Each double acquisition can be

implemented using two pads configured as GPIs by the SIU unit. Digital input signal shall be