SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
Safety-critical applications require run-time detection of faults in critical components in the device such as the Central Processing Unit (CPU) and the Vectored Interrupt Controller Module (VIM). For this purpose, the CPU Compare Module for Cortex-R5F (CCM-R5F) compares the core bus outputs of two Cortex-R5F CPUs running in a 1oo1D (one-out-of-one, with diagnostics) lockstep configuration. Each R5FSS also implements two VIM modules in 1oo1D (one-out-of-one, with diagnostic) lockstep configuration. Any difference in the core compare bus outputs of the CPUs or the VIMs is flagged as an error. For diagnostic purposes, the CCM-R5F also incorporates a self-test capability to allow for boot time checking of hardware faults within the CCM-R5F itself.
In addition to comparing the CPU's and VIM's outputs for fault detection during run-time, the CCM-R5F also incorporates one additional run-time diagnostic feature: the Checker-CPU Inactivity Monitor.
The Checker-CPU inactivity monitor monitors the checker CPU's key bus signals to the interconnect. When the two CPUs are in lockstep configuration, several key bus signals from the checker CPU which would have indicated a valid bus transaction to the interconnect on the microcontroller will be monitored. A list of the signals to be monitored is provided in theChecker CPU Signals to Monitor table. These signals from the checker CPU are expected to be inactive. All transactions between the lockstep CPUs and the rest of the system should only go through the main CPU. Any signals which indicate activity will be flagged as an error.