SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
In error forcing mode, a test pattern is applied to the CPU related inputs of the compare logic to force an error at the compare error signal of the compare unit. The core compare disabled signal is asserted on entry and de-asserted when complete.
This mode is enabled by writing the dedicated key in the R5FSS_CCMKEYR1 key register (see Table 6-15). The error signal is generated by asserting the CPU compare error signal.
Error forcing mode is similar to the compare mismatch test operation of self test mode, in which an un-equal vector is injected into the CCMR5 CPU signal ports. Instead of setting a self test error flag and asserting self test error signal, the error forcing mode forces the compare mismatch to set the compare error flag (CMPE1) and assert the compare error signal.
Only one hardcoded test pattern is applied into CCMR5 during error forcing mode. A repeated 0x5 pattern is applied to CPU0 signal port, while a repeated 0xA pattern is applied to the CPU1 signal port. The error forcing mode takes one cycle to complete. Hence, the failing signature is presented for one clock cycle and the mode is automatically switched to lockstep mode and the R5FSS_CCMKEYR1 key register will show the lockstep key (0000). During this cycle the CPUs are not compared. The user should expect to receive the error signal from CCMR5 module once the error forcing mode is entered. If no error signal is set, then a hardware fault is present.