The NORMAL register type allows data to be written and read from. All 16-bits of the data are registered at the same time. There is no synchronizing with an internal clock thus all register writes are asynchronous with respect to internal clocks. There are three subtypes of NORMAL:
- AUTOSYNC: A NORMAL register that causes a sync to be generated after the write is finished. These are used when it is desirable to synchronize the block after writing the register or for a single field that spans across multiple registers. For instance, the NCO requires three 16-bit register writes to set the frequency. Upon writing the last of these registers an autosync is generated to deliver the entire field to the NCO block at once, rather than in pieces after each individual register write. For a field that spans multiple registers, all non-AUTOSYNC registers for the field must be written first before the actual AUTOSYNC register.
- No RESET Value: These are NORMAL registers, but the reset value cannot be specified. This could be because the register has some read_only bits or some internal logic partially controls the bit values.
- READ_ONLY (R): Registers that can only be read.