3.6.31 Disable and periodic cross-check of unintentional activation of unused peripherals
This section reports the safety mechanism that addresses peripherals not used by the safety application, or not
used at all.
Table 114. FFI_SM_0
SM CODE FFI_SM_0
Description Unused peripherals disable
Ownership End user
Detailed implementation
This method contributes to the reduction of the probability of cross-interferences caused by
peripherals not used by the software application, in case a hardware failure causes an unintentional
activation.
After the system boot, the application software must disable all unused peripherals with this
procedure:
• Enable reset flag on AHB and APB peripheral reset register
• Disable clock distribution on AHB and APB peripheral clock enable register
Error reporting NA
Fault detection time NA
Addressed fault model NA
Dependency on MCU configuration None
Initialization NA
Periodicity Startup
Test for the diagnostic Not needed
Multiple faults protection FFI_SM_1: Periodical read-back of interference avoidance registers
Recommendations and known limitations None
Table 115. FFI_SM_1
SM CODE FFI_SM_1
Description Periodical read-back of interference avoidance registers
Ownership End user
Detailed implementation
This method contributes to the reduction of the probability of cross-interferences between
peripherals that can potentially conflict on the same input/output pins, including for instance unused
peripherals. This diagnostic measure must be applied to following registers:
• Clock enable and disable registers
• Alternate functions programming registers
Detailed information on the implementation of this method can be found in Section 3.6.5
Error reporting Refer to NVIC_SM_0
Fault detection time Refer to NVIC_SM_0
Addressed fault model Refer to NVIC_SM_0
Dependency on MCU configuration Refer to NVIC_SM_0
Initialization Refer to NVIC_SM_0
Periodicity Refer to NVIC_SM_0
Test for the diagnostic Refer to NVIC_SM_0
Multiple faults protection Refer to NVIC_SM_0
UM1845
Description of hardware and software diagnostics
UM1845 - Rev 4
page 76/108
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