SPRUHX5I August 2014 – May 2024 TMS320F28374S , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376S , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378S , TMS320F28379S
Since error detection and correction logic are part of safety-critical logic, safety applications need to make sure that the SECDED logic is always working properly. For these safety concerns, make sure the correctness of the SECDED logic, an ECC test mode is provided to test the correctness of ECC logic periodically. In this ECC test mode, data/ECC and address inputs to the ECC logic are controlled by the ECC test mode registers FDATAH_TEST, FDATAL_TEST, FECC_TEST, and FADDR_TEST, respectively. Using this test mode, users can introduce single-bit errors, double-bit errors, or address errors and check whether or not SECDED logic is catching those errors. Users can also check if SECDED logic is reporting any false errors when no errors are introduced.
This ECC test mode can be enabled by setting the ECC_TEST_EN bit in the FECC_CTRL register. When ECC test mode is enabled, the CPU cannot read the data from Flash and instead the CPU gets data from the ECC test mode registers (FDATAH_TEST/FDATAL_TEST). This is because ECC test mode registers (FDATAH_TEST, FDATAL_TEST, FECC_TEST) are multiplexed with data from the Flash. Hence, the CPU must not read/fetch from Flash when ECC test mode is enabled. For this reason, ECC test mode code must be executed from RAM and not from Flash.
Only one of the SECDED modules (out of the two SECDED modules that work on lower 64 bits and upper 64 bits of a read 128-bit data) at a time can be tested. The ECC_SELECT bit in the FECC_CTRL register can be configured by users to select one of the SECDED modules for test.
To test the ECC logic using ECC test mode, users can follow the steps below:
Once the above ECC test mode registers are written by the user: