The APB and AXI-programming interfaces are accessed using single 32-bit read/write transactions. These memory-mapped registers can be read, write, or have another access type. The access type is included with each register; the acronyms are listed in the appendix of the register reference.
Access to the programming interfaces is protected with local fixed security requirements or have programmable security provided by an XPPU or XMPU protection unit.
Recommended: The registers are
described in the register reference manuals. Software should perform a
read-modify-write to all registers that include a reserved or unknown bit
field.