AN3077 datasheet(48/82 Pages) STMICROELECTRONICS

48 / 82 page

Functional safety requirements for application software

AN3077

48/82

DocID16384 Rev 10

Recommended: The CRC module should be used to detect accidental alteration of data

during transmission or storage. The CRC takes as its input a data stream of any length and

produces a 32-bit output value.

Mandatory: The CRC calculation shall be executed to verify the content of the registers.

Note:

Rationale: The contents of the configuration registers of the safety-related modules must

be checked within the FTTI.

Note:

Theoretically, the CPU could be used instead of the CRC to verify that the value of the

configuration registers have not changed. However, using the CRC is more effective.

Note:

Implementation hint: The CRC of the configuration registers of the modules involved with

the safety function shall be calculated offline.

At run time, the same CRC value shall be calculated by the CRC module within the safety

process time. To avoid overloading the CPU, the eDMA module can be used to support the

data transfer from the registers under check to the CRC module.

The result of the runtime computation is then compared to the value of the offline CRC.

The application must include detection, or protection measures, against possible faults of

the CRC module only if the CRC module is used by any SEF.

3.20

Clock Monitor Unit (CMU)

The main task of the Clock Monitor Unit (CMU) is to supervise the integrity of various clock

sources.

Mandatory: The following supervisor functions shall be used:

●

Loss of external crystal oscillator clock

●

FMPLL frequency higher than a (programmable) value set as high reference

●

FMPLL frequency lower than a (programmable) value set as low reference

Note:

Rationale: To monitor the integrity of the clock signals

This error information is forwarded to the FCCU and to the MC_RGM.

Device_Number includes three CMUs:

●

CMU_0 monitors the clock signal of the SoR modules and the clock from the XOSC

(XOSC_CLK).

●

CMU_1 monitors the clock signal used by the motor control related peripherals (such

as eTimer, FlexPWM, CTU and ADC).

●

CMU_2 monitors the clock signal for the protocol engine of the FlexRay module.

Mandatory: For ASIL D applications, use of the CMU is mandatory. If the related modules

are used by the application safety function, the user shall verify that the CMUs are enabled

and their faults managed by the FCCU.

Note:

Rationale: To monitor the integrity of the various clock signals

AN3077 датащи(PDF) 48 Page - STMicroelectronics

AN3077 датащи(HTML) 48 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82

датащи скачать

ссылки URL