SFFS779 December 2024 TMS320F28P550SG , TMS320F28P550SJ
As a fault avoidance safety measure for key registers of the FSI module, registers are protected by EALLOW privilege, register keys, and an initiator register lock. These protections avoid spurious writes or unintentional modifications to these registers. Some bits in the FSI registers are protected by a key. To write to these bits, the key must be written at the same time.
The control register lock prevents any writes to the control registers until the lock is released. To set the control register lock, write 0xA501 to RX_LOCK_CTRL and TX_LOCK_CTRL for the receiver and transmitter, respectively.