Functional safety requirements for application software
Safety Manual for MPC5777M, Rev. 1.1
NXP Semiconductors 23
To run the LVD/HVD self-test, application software shall execute the following steps:
These steps shall be repeated for each LVD (or HVD) to be tested. See the following sections of the
MPC5777M Reference Manual:
• “Power Management Controller digital interface (PMC_dig)” chapter, “Voltage Detect User Mode
Test Register (VD_UTST)” section
• “Device Configuration” chapter, “LVD / HVD self test” section
3.2.12 Temperature monitoring configuration
The MPC5777M supports a temperature sensor to detect over-temperature conditions. The temperature
sensor can be configured to provide an analog measurement of the temperature using SARB input channel
120.
To set a proper threshold the customer must consider the maximum operating junction temperature (see
the MPC5777M Data Sheet for the temperature sensor accuracy and maximum junction temperatures).
1. Mask LVD/HVD by clearing the Reset Event Enable Register (PMC_REE_TD, PMC_REE_VDn
registers) of the PMC (see the "Power Management Controller digital interface (PMC_dig)"
chapter in the MPC5777M Reference Manual).
2. Clear LVD/HVD in Event Pending Register (PMC_REE_TD, PMC_REE_VDn).
3. Write the PMC_VD_UTST register to the desired LVD/HVD to test.
4. Enable VD_UTST bits in MCR (PMC_MCR) by setting USER_SELF_TEST_EN to start testing.
5. Verify test results by polling the Event Pending Registers (PMC_EPR_VDn or PMC_EPR_TD)
flag:
a) If the flag is set, the LVD (or HVD) test passed as expected.
b) If the flag is not set, self-test failed.
NOTE
Software may configure a timeout period to be sure the flag asserts within a
specified time (this time shall be greater than 20 μs).
6. Disable the VD_UTST bits in MCR (PMC_MCR) by clearing the USER_SELF_TEST_EN to end
the test.
7. Clear PMC_VD_UTST.
8. Clear the LVD (or HVD) flag in the Event Pending Register (PMC_EPR_TD or PMC_EPR_VDn).
9. Wait for the PMC_GR_S bit to be de-asserted.
NOTE
Software may configure a timeout period to be sure the flag or flags clear
within a specified time.
10. Enable the LVD (or HVD) by setting the appropriate field in the Reset Event Enable Register
(PMC_REE_TD or PMC_REE_VDn).
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