Safety Manual for MPC5777M, Rev. 1.1
Functional safety requirements for application software
NXP Semiconductors10
3.1.2 Test mode
Several mechanisms of the MPC5777M can be circumvented in test mode, undermining the safety
concept. Test mode is used for comprehensive factory testing and should not be used in normal operating
mode.
The TEST pin is for testing purposes only and should be allowed to float in the user application. The
system must ensure the TEST pin is not asserted during boot to enable test mode. (The TESTMODE pad
has an internal pull-down that is always active to keep it from asserting during normal operation.) The
activation of test mode is supervised by the FCCU and will signal a fault condition when test mode is
entered.
Assumption: [SCG18.025]Test mode will be disabled in the field while the device is being used for
safety-relevant functions. [end]
To avoid unwanted activation of the testing circuitry the Design For Testability (DFTn) FCCU error inputs
must be enabled even if they are not needed by the application. The FCCU channels for DFT[1:4] are 46
to 49, respectively. These error inputs are enabled by setting the appropriate bits in the following registers:
• FCCU_RF_CFG
• FCCU_RFS_CFG
• FCCU_RF_TOE
• FCCU_RF_E
• FCCU_IRQ_ALARM_EN
• FCCU_NMI_EN
• FCCU_EOUT_SIG_EN
3.2 Initial checks and configurations
After start-up, the application software must ensure the conditions described in this section are satisfied
before safety-relevant functions are enabled. Additional configuration is needed to ensure freedom from
interference between cores and between concurrent software (see Section 3.4, Operational interference
protection).
3.2.1 I/O ball configuration
Assumption: [SCG18.120]The user shall avoid configurations that place redundant signals on
neighboring pads or pins. [end]
[SCG18.121]To determine whether two functions on two package balls are adjacent to each other, refer to
the mechanical drawings of the packages (see the MPC5777M Data Sheet) together with the spheres
(balls) number information of the packages as seen in the MPC5777M Reference Manual’s “System
Integration Unit Lite2 (SIUL2)” section together with the ball information provided in the document
"MPC5777M_System_IO_Description_and_Input_multiplexing_tables" that is attached to the
MPC5777M Reference Manual. [end]
To Next Page
Loading...
Need help?
General
