14.5.3 ECC Initialization
With ECC enabled, a write access of less than 64 bits for ITCM or 32 bits for DTCM forces a read-modify-write operation to calculate the correct ECC bits for the corresponding 64-bit/32-bit data word. This read-modify-write will most likely result in a false double bit error.
The DRMTCM(ECC) module will automatically calculate ECC and store the data with ECC bits to the memory address location of the write when a full 64 bits (for ITCM) or 32 bits (for DTCM) is provided.