Table 69. Atim_Sm_2; Table 70. Atim_Sm_3 - ST STM32F2 Series User Manual

SM CODE
Recommendations and known
limitations
SM CODE
Description
Ownership
Detailed implementation
Error reporting
Fault detection time
Addressed fault model
Dependency on MCU configuration
Initialization
Periodicity
Test for the diagnostic
Multiple faults protection
Recommendations and known
limitations
SM CODE
Description
Ownership
Detailed implementation
Error reporting
Fault detection time
Addressed fault model
Dependency on MCU
configuration
UM1845 - Rev 4
ATIM_SM_1
Tolerance implementation in timer checks is recommended to avoid false positive outcomes of the
diagnostic.
This method apply to timer channels merely used as elapsed time counters
Table 69.
ATIM_SM_2
1oo2 for input capture timers
End user
This method is conceived to protect timers used for external signal acquisition and measurement,
like "input capture" and "encoder reading". Implementation requires to connect the external signals
also to a redundant timer, and to perform a coherence check on the measured data at application
level.
Coherence check between timers is executed each time the reading is used by the application
software
Depends on implementation
Depends on implementation
Permanent and Transient
None
Depends on implementation
On demand
Not needed
CPU_SM_0: periodical core self-test software
To reduce the potential effect of common cause failures, it is suggested to use for redundant check a
channel belonging to a different timer module and mapped to non-adjacent pin on the device
package
Table 70.
ATIM_SM_3
Loopback scheme for PWM outputs
End user
This method is implemented by connecting the PWM to a separate timer channel to acquire the generated
waveform characteristics.
The guidelines are the following:
• Both PWM frequency and duty cycle are measured and checked versus the expected value.
• To reduce the potential effect of common cause failure, it is suggested to use for the loopback check a
channel belonging to a different timer module and mapped to non-adjacent pins on the device
package.
This measure can be replaced under the end-user responsibility by different loopback schemes already in
place in the final application and rated as equivalent. For example if the PWM is used to drive an external
power load, the reading of the on-line current value can be used instead of the PWM duty cycle
measurement.
Depends on implementation
Depends on implementation
Permanent and Transient
None
Description of hardware and software diagnostics
ATIM_SM_2
ATIM_SM_3
UM1845
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