Table 75. Gpio_Sm_3 - ST STM32F2 Series User Manual

SM CODE
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
Initialization
Periodicity
Test for the diagnostic
Multiple faults protection
Recommendations and known limitations
UM1845 - Rev 4
GPIO_SM_2
End user
This method addresses GPIO lines used as outputs. Implementation is done by a loopback scheme,
connecting the output to a different GPIO line programmed as input and by using the input line to check
the expected value on output port. Comparison is executed by application software periodically and each
time output is updated
Depends on implementation
Depends on implementation
Permanent and Transient
None
Depends on implementation
Continuous
Not needed
CPU_SM_0: periodical core self-test software
To reduce the potential impact of common cause failure, it is recommended to use GPIO lines:
• belonging to different i/o ports (for instance PORT A and B)
• with different bit number (for instance PORTA.1 and PORTB.5)
• mapped to non-adjacent pins on the device package
Efficiency versus transient failures is linked to final application characteristics. We define as Tm the
minimum duration of GPIO output wrong signal permanence required to violate the related safety
function(s). Efficiency is maximized when execution test frequency is higher than 1/Tm
Table 75.
GPIO_SM_3
GPIO port configuration lock register
ST
This safety mechanism prevents configuration changes for GPIO registers; it addresses therefore
systematic faults in software application.
The use of this method is encouraged to enhance the end-application robustness for systematic
faults
Depends on implementation
Depends on implementation
None (Systematic only)
None
The correct write sequence must be applied to bit 16 (LCKK) of GPIOx_LCKR after the final GPIO
configuration has been written by the application software.
Continuous
Not needed
Not needed
This method does not address transient faults (soft errors) that can possibly cause bit-flips on GPIO
registers at running time
Description of hardware and software diagnostics
GPIO_SM_3
UM1845
page 53/108